// was:moveToChild
private RC MoveToChild(Pgno newID)
{
var id = PageID;
var newPage = new MemPage();
Debug.Assert(HoldsMutex());
Debug.Assert(State == CursorState.VALID);
Debug.Assert(PageID < BTCURSOR_MAX_DEPTH);
if (PageID >= (BTCURSOR_MAX_DEPTH - 1))
{
return(SysEx.SQLITE_CORRUPT_BKPT());
}
var rc = Shared.getAndInitPage(newID, ref newPage);
if (rc != RC.OK)
{
return(rc);
}
Pages[id + 1] = newPage;
PagesIndexs[id + 1] = 0;
PageID++;
Info.nSize = 0;
ValidNKey = false;
if (newPage.Cells < 1 || newPage.HasIntKey != Pages[id].HasIntKey)
{
return(SysEx.SQLITE_CORRUPT_BKPT());
}
return(RC.OK);
}
internal MemPage btreePageLookup(Pgno pgno)
{
Debug.Assert(MutexEx.Held(this.Mutex));
var pDbPage = this.Pager.Lookup(pgno);
return(pDbPage ? MemPage.btreePageFromDbPage(pDbPage, pgno, this) : null);
}
internal RC ptrmapGet(Pgno key, ref PTRMAP pEType, ref Pgno pPgno)
{
Debug.Assert(MutexEx.Held(this.Mutex));
var iPtrmap = (int)MemPage.PTRMAP_PAGENO(this, key);
var pDbPage = new PgHdr(); // The pointer map page
var rc = this.Pager.Get((Pgno)iPtrmap, ref pDbPage);
if (rc != RC.OK)
{
return(rc);
}
var pPtrmap = Pager.sqlite3PagerGetData(pDbPage);// Pointer map page data
var offset = (int)MemPage.PTRMAP_PTROFFSET((Pgno)iPtrmap, key);
if (offset < 0)
{
Pager.Unref(pDbPage);
return(SysEx.SQLITE_CORRUPT_BKPT());
}
Debug.Assert(offset <= (int)this.UsableSize - 5);
var v = pPtrmap[offset];
if (v < 1 || v > 5)
{
return(SysEx.SQLITE_CORRUPT_BKPT());
}
pEType = (PTRMAP)v;
pPgno = ConvertEx.Get4(pPtrmap, offset + 1);
Pager.Unref(pDbPage);
return(RC.OK);
}
static int NB = (NN * 2 + 1); // Total pages involved in the balance
#endregion Fields
#if !SQLITE_OMIT_QUICKBALANCE
internal static RC balance_quick(MemPage parentPage, MemPage page, byte[] space)
{
Debug.Assert(MutexEx.Held(page.Shared.Mutex));
Debug.Assert(Pager.IsPageWriteable(parentPage.DbPage));
Debug.Assert(page.NOverflows == 1);
// This error condition is now caught prior to reaching this function
if (page.Cells <= 0)
return SysEx.SQLITE_CORRUPT_BKPT();
// Allocate a new page. This page will become the right-sibling of pPage. Make the parent page writable, so that the new divider cell
// may be inserted. If both these operations are successful, proceed.
var shared = page.Shared; // B-Tree Database
var newPage = new MemPage(); // Newly allocated page
Pgno pgnoNew = 0; // Page number of pNew
var rc = shared.allocateBtreePage(ref newPage, ref pgnoNew, 0, 0);
if (rc != RC.OK)
return rc;
var pOut = 4;
var pCell = page.Overflows[0].Cell;
var szCell = new int[1] { page.cellSizePtr(pCell) };
Debug.Assert(Pager.IsPageWriteable(newPage.DbPage));
Debug.Assert(page.Data[0] == (Btree.PTF_INTKEY | Btree.PTF_LEAFDATA | Btree.PTF_LEAF));
newPage.zeroPage(Btree.PTF_INTKEY | Btree.PTF_LEAFDATA | Btree.PTF_LEAF);
newPage.assemblePage(1, pCell, szCell);
// If this is an auto-vacuum database, update the pointer map with entries for the new page, and any pointer from the
// cell on the page to an overflow page. If either of these operations fails, the return code is set, but the contents
// of the parent page are still manipulated by thh code below. That is Ok, at this point the parent page is guaranteed to
// be marked as dirty. Returning an error code will cause a rollback, undoing any changes made to the parent page.
#if !SQLITE_OMIT_AUTOVACUUM
if (shared.AutoVacuum)
#else
if (false)
#endif
{
shared.ptrmapPut(pgnoNew, PTRMAP.BTREE, parentPage.ID, ref rc);
if (szCell[0] > newPage.MinLocal)
newPage.ptrmapPutOvflPtr(pCell, ref rc);
}
// Create a divider cell to insert into pParent. The divider cell consists of a 4-byte page number (the page number of pPage) and
// a variable length key value (which must be the same value as the largest key on pPage).
// To find the largest key value on pPage, first find the right-most cell on pPage. The first two fields of this cell are the
// record-length (a variable length integer at most 32-bits in size) and the key value (a variable length integer, may have any value).
// The first of the while(...) loops below skips over the record-length field. The second while(...) loop copies the key value from the
// cell on pPage into the pSpace buffer.
var iCell = page.FindCell(page.Cells - 1);
pCell = page.Data;
var _pCell = iCell;
var pStop = _pCell + 9;
while (((pCell[_pCell++]) & 0x80) != 0 && _pCell < pStop) ;
pStop = _pCell + 9;
while (((space[pOut++] = pCell[_pCell++]) & 0x80) != 0 && _pCell < pStop) ;
// Insert the new divider cell into pParent.
parentPage.insertCell(parentPage.Cells, space, pOut, null, page.ID, ref rc);
// Set the right-child pointer of pParent to point to the new page.
ConvertEx.Put4L(parentPage.Data, parentPage.HeaderOffset + 8, pgnoNew);
// Release the reference to the new page.
newPage.releasePage();
return rc;
}
internal RC clearDatabasePage(Pgno pgno, int freePageFlag, ref int pnChange)
{
var pPage = new MemPage();
Debug.Assert(MutexEx.Held(this.Mutex));
if (pgno > btreePagecount())
{
return(SysEx.SQLITE_CORRUPT_BKPT());
}
var rc = getAndInitPage(pgno, ref pPage);
if (rc != RC.OK)
{
return(rc);
}
for (var i = 0; i < pPage.Cells; i++)
{
var iCell = pPage.FindCell(i);
var pCell = pPage.Data;
if (pPage.Leaf == 0)
{
rc = clearDatabasePage(ConvertEx.Get4(pCell, iCell), 1, ref pnChange);
if (rc != RC.OK)
{
goto cleardatabasepage_out;
}
}
rc = pPage.clearCell(iCell);
if (rc != RC.OK)
{
goto cleardatabasepage_out;
}
}
if (pPage.Leaf == 0)
{
rc = clearDatabasePage(ConvertEx.Get4(pPage.Data, 8), 1, ref pnChange);
if (rc != RC.OK)
{
goto cleardatabasepage_out;
}
}
else
{
pnChange += pPage.Cells;
}
if (freePageFlag != 0)
{
pPage.freePage(ref rc);
}
else if ((rc = Pager.Write(pPage.DbPage)) == RC.OK)
{
pPage.zeroPage(pPage.Data[0] | Btree.PTF_LEAF);
}
cleardatabasepage_out:
pPage.releasePage();
return(rc);
}
internal RC btreeGetPage(Pgno pgno, ref MemPage ppPage, int noContent)
{
Debug.Assert(MutexEx.Held(this.Mutex));
DbPage pDbPage = null;
var rc = this.Pager.Get(pgno, ref pDbPage, (byte)noContent);
if (rc != RC.OK)
return rc;
ppPage = MemPage.btreePageFromDbPage(pDbPage, pgno, this);
return RC.OK;
}
internal RC getOverflowPage(Pgno ovfl, out MemPage ppPage, out Pgno pPgnoNext)
{
Pgno next = 0;
MemPage pPage = null;
ppPage = null;
var rc = RC.OK;
Debug.Assert(MutexEx.Held(this.Mutex));
// Debug.Assert( pPgnoNext != 0);
#if !SQLITE_OMIT_AUTOVACUUM
// Try to find the next page in the overflow list using the autovacuum pointer-map pages. Guess that the next page in
// the overflow list is page number (ovfl+1). If that guess turns out to be wrong, fall back to loading the data of page
// number ovfl to determine the next page number.
if (this.AutoVacuum)
{
Pgno pgno = 0;
Pgno iGuess = ovfl + 1;
PTRMAP eType = 0;
while (MemPage.PTRMAP_ISPAGE(this, iGuess) || iGuess == MemPage.PENDING_BYTE_PAGE(this))
{
iGuess++;
}
if (iGuess <= btreePagecount())
{
rc = ptrmapGet(iGuess, ref eType, ref pgno);
if (rc == RC.OK && eType == PTRMAP.OVERFLOW2 && pgno == ovfl)
{
next = iGuess;
rc = RC.DONE;
}
}
}
#endif
Debug.Assert(next == 0 || rc == RC.DONE);
if (rc == RC.OK)
{
rc = btreeGetPage(ovfl, ref pPage, 0);
Debug.Assert(rc == RC.OK || pPage == null);
if (rc == RC.OK)
{
next = ConvertEx.Get4(pPage.Data);
}
}
pPgnoNext = next;
if (ppPage != null)
{
ppPage = pPage;
}
else
{
pPage.releasePage();
}
return(rc == RC.DONE ? RC.OK : rc);
}
internal static void assertParentIndex(MemPage pParent, int iIdx, Pgno iChild)
{
Debug.Assert(iIdx <= pParent.Cells);
if (iIdx == pParent.Cells)
{
Debug.Assert(ConvertEx.Get4(pParent.Data, pParent.HeaderOffset + 8) == iChild);
}
else
{
Debug.Assert(ConvertEx.Get4(pParent.Data, pParent.FindCell(iIdx)) == iChild);
}
}
// was:moveToParent
private void MoveToParent()
{
Debug.Assert(HoldsMutex());
Debug.Assert(State == CursorState.VALID);
Debug.Assert(PageID > 0);
Debug.Assert(Pages[PageID] != null);
MemPage.assertParentIndex(Pages[PageID - 1], PagesIndexs[PageID - 1], Pages[PageID].ID);
Pages[PageID].releasePage();
PageID--;
Info.nSize = 0;
ValidNKey = false;
}
internal RC btreeGetPage(Pgno pgno, ref MemPage ppPage, int noContent)
{
Debug.Assert(MutexEx.Held(this.Mutex));
DbPage pDbPage = null;
var rc = this.Pager.Get(pgno, ref pDbPage, (byte)noContent);
if (rc != RC.OK)
{
return(rc);
}
ppPage = MemPage.btreePageFromDbPage(pDbPage, pgno, this);
return(RC.OK);
}
internal void ptrmapPut(Pgno key, PTRMAP eType, Pgno parent, ref RC rRC)
{
if (rRC != RC.OK)
{
return;
}
Debug.Assert(MutexEx.Held(this.Mutex));
// The master-journal page number must never be used as a pointer map page
Debug.Assert(!MemPage.PTRMAP_ISPAGE(this, MemPage.PENDING_BYTE_PAGE(this)));
Debug.Assert(this.AutoVacuum);
if (key == 0)
{
rRC = SysEx.SQLITE_CORRUPT_BKPT();
return;
}
var iPtrmap = MemPage.PTRMAP_PAGENO(this, key);
var pDbPage = new PgHdr(); // The pointer map page
var rc = this.Pager.Get(iPtrmap, ref pDbPage);
if (rc != RC.OK)
{
rRC = rc;
return;
}
var offset = (int)MemPage.PTRMAP_PTROFFSET(iPtrmap, key);
if (offset < 0)
{
rRC = SysEx.SQLITE_CORRUPT_BKPT();
goto ptrmap_exit;
}
Debug.Assert(offset <= (int)this.UsableSize - 5);
var pPtrmap = Pager.sqlite3PagerGetData(pDbPage); // The pointer map data
if (eType != (PTRMAP)pPtrmap[offset] || ConvertEx.Get4(pPtrmap, offset + 1) != parent)
{
Btree.TRACE("PTRMAP_UPDATE: {0}->({1},{2})", key, eType, parent);
rRC = rc = Pager.Write(pDbPage);
if (rc == RC.OK)
{
pPtrmap[offset] = (byte)eType;
ConvertEx.Put4L(pPtrmap, (uint)offset + 1, parent);
}
}
ptrmap_exit:
Pager.Unref(pDbPage);
}
internal Pgno ptrmapPageno(Pgno pgno)
{
Debug.Assert(MutexEx.Held(this.Mutex));
if (pgno < 2)
{
return(0);
}
var nPagesPerMapPage = (int)(this.UsableSize / 5 + 1);
var iPtrMap = (Pgno)((pgno - 2) / nPagesPerMapPage);
var ret = (Pgno)(iPtrMap * nPagesPerMapPage) + 2;
if (ret == MemPage.PENDING_BYTE_PAGE(this))
{
ret++;
}
return(ret);
}
internal static RC balance_deeper(MemPage pRoot, ref MemPage ppChild)
{
MemPage pChild = null; // Pointer to a new child page
Pgno pgnoChild = 0; // Page number of the new child page
var pBt = pRoot.Shared;
Debug.Assert(pRoot.NOverflows > 0);
Debug.Assert(MutexEx.Held(pBt.Mutex));
// Make pRoot, the root page of the b-tree, writable. Allocate a new page that will become the new right-child of pPage. Copy the contents
// of the node stored on pRoot into the new child page.
var rc = Pager.Write(pRoot.DbPage);
if (rc == RC.OK)
{
rc = pBt.allocateBtreePage(ref pChild, ref pgnoChild, pRoot.ID, 0);
copyNodeContent(pRoot, pChild, ref rc);
#if !SQLITE_OMIT_AUTOVACUUM
if (pBt.AutoVacuum)
#else
if (false)
#endif
{
pBt.ptrmapPut(pgnoChild, PTRMAP.BTREE, pRoot.ID, ref rc);
}
}
if (rc != RC.OK)
{
ppChild = null;
pChild.releasePage();
return(rc);
}
Debug.Assert(Pager.IsPageWriteable(pChild.DbPage));
Debug.Assert(Pager.IsPageWriteable(pRoot.DbPage));
Debug.Assert(pChild.Cells == pRoot.Cells);
Btree.TRACE("BALANCE: copy root %d into %d\n", pRoot.ID, pChild.ID);
// Copy the overflow cells from pRoot to pChild
Array.Copy(pRoot.Overflows, pChild.Overflows, pRoot.NOverflows);
pChild.NOverflows = pRoot.NOverflows;
// Zero the contents of pRoot. Then install pChild as the right-child.
pRoot.zeroPage(pChild.Data[0] & ~Btree.PTF_LEAF);
ConvertEx.Put4L(pRoot.Data, pRoot.HeaderOffset + 8, pgnoChild);
ppChild = pChild;
return(RC.OK);
}
internal static RC balance_deeper(MemPage pRoot, ref MemPage ppChild)
{
MemPage pChild = null; // Pointer to a new child page
Pgno pgnoChild = 0; // Page number of the new child page
var pBt = pRoot.Shared;
Debug.Assert(pRoot.NOverflows > 0);
Debug.Assert(MutexEx.Held(pBt.Mutex));
// Make pRoot, the root page of the b-tree, writable. Allocate a new page that will become the new right-child of pPage. Copy the contents
// of the node stored on pRoot into the new child page.
var rc = Pager.Write(pRoot.DbPage);
if (rc == RC.OK)
{
rc = pBt.allocateBtreePage(ref pChild, ref pgnoChild, pRoot.ID, 0);
copyNodeContent(pRoot, pChild, ref rc);
#if !SQLITE_OMIT_AUTOVACUUM
if (pBt.AutoVacuum)
#else
if (false)
#endif
{
pBt.ptrmapPut(pgnoChild, PTRMAP.BTREE, pRoot.ID, ref rc);
}
}
if (rc != RC.OK)
{
ppChild = null;
pChild.releasePage();
return rc;
}
Debug.Assert(Pager.IsPageWriteable(pChild.DbPage));
Debug.Assert(Pager.IsPageWriteable(pRoot.DbPage));
Debug.Assert(pChild.Cells == pRoot.Cells);
Btree.TRACE("BALANCE: copy root %d into %d\n", pRoot.ID, pChild.ID);
// Copy the overflow cells from pRoot to pChild
Array.Copy(pRoot.Overflows, pChild.Overflows, pRoot.NOverflows);
pChild.NOverflows = pRoot.NOverflows;
// Zero the contents of pRoot. Then install pChild as the right-child.
pRoot.zeroPage(pChild.Data[0] & ~Btree.PTF_LEAF);
ConvertEx.Put4L(pRoot.Data, pRoot.HeaderOffset + 8, pgnoChild);
ppChild = pChild;
return RC.OK;
}
// was:moveToRightmost
private RC MoveToRightmost()
{
Debug.Assert(HoldsMutex());
Debug.Assert(State == CursorState.VALID);
var rc = RC.OK;
MemPage page = null;
while (rc == RC.OK && (page = Pages[PageID]).Leaf == 0)
{
var pgno = (Pgno)ConvertEx.Get4(page.Data, page.HeaderOffset + 8);
PagesIndexs[PageID] = page.Cells;
rc = MoveToChild(pgno);
}
if (rc == RC.OK)
{
PagesIndexs[PageID] = (ushort)(page.Cells - 1);
Info.nSize = 0;
ValidNKey = false;
}
return(rc);
}
internal static void copyNodeContent(MemPage pFrom, MemPage pTo, ref RC pRC)
{
if (pRC != RC.OK)
{
return;
}
var pBt = pFrom.Shared;
var aFrom = pFrom.Data;
var aTo = pTo.Data;
var iFromHdr = pFrom.HeaderOffset;
var iToHdr = (pTo.ID == 1 ? 100 : 0);
Debug.Assert(pFrom.HasInit);
Debug.Assert(pFrom.FreeBytes >= iToHdr);
Debug.Assert(ConvertEx.Get2(aFrom, iFromHdr + 5) <= (int)pBt.UsableSize);
// Copy the b-tree node content from page pFrom to page pTo.
var iData = (int)ConvertEx.Get2(aFrom, iFromHdr + 5);
Buffer.BlockCopy(aFrom, iData, aTo, iData, (int)pBt.UsableSize - iData);
Buffer.BlockCopy(aFrom, iFromHdr, aTo, iToHdr, pFrom.CellOffset + 2 * pFrom.Cells);
// Reinitialize page pTo so that the contents of the MemPage structure match the new data. The initialization of pTo can actually fail under
// fairly obscure circumstances, even though it is a copy of initialized page pFrom.
pTo.HasInit = false;
var rc = pTo.btreeInitPage();
if (rc != RC.OK)
{
pRC = rc;
return;
}
// If this is an auto-vacuum database, update the pointer-map entries for any b-tree or overflow pages that pTo now contains the pointers to.
#if !SQLITE_OMIT_AUTOVACUUM
if (pBt.AutoVacuum)
#else
if (false)
#endif
{
pRC = pTo.setChildPtrmaps();
}
}
internal RC clearDatabasePage(Pgno pgno, int freePageFlag, ref int pnChange)
{
var pPage = new MemPage();
Debug.Assert(MutexEx.Held(this.Mutex));
if (pgno > btreePagecount())
return SysEx.SQLITE_CORRUPT_BKPT();
var rc = getAndInitPage(pgno, ref pPage);
if (rc != RC.OK)
return rc;
for (var i = 0; i < pPage.Cells; i++)
{
var iCell = pPage.FindCell(i);
var pCell = pPage.Data;
if (pPage.Leaf == 0)
{
rc = clearDatabasePage(ConvertEx.Get4(pCell, iCell), 1, ref pnChange);
if (rc != RC.OK)
goto cleardatabasepage_out;
}
rc = pPage.clearCell(iCell);
if (rc != RC.OK)
goto cleardatabasepage_out;
}
if (pPage.Leaf == 0)
{
rc = clearDatabasePage(ConvertEx.Get4(pPage.Data, 8), 1, ref pnChange);
if (rc != RC.OK)
goto cleardatabasepage_out;
}
else
pnChange += pPage.Cells;
if (freePageFlag != 0)
pPage.freePage(ref rc);
else if ((rc = Pager.Write(pPage.DbPage)) == RC.OK)
pPage.zeroPage(pPage.Data[0] | Btree.PTF_LEAF);
cleardatabasepage_out:
pPage.releasePage();
return rc;
}
internal RC getAndInitPage(Pgno pgno, ref MemPage ppPage)
{
Debug.Assert(MutexEx.Held(this.Mutex));
RC rc;
if (pgno > btreePagecount())
{
rc = SysEx.SQLITE_CORRUPT_BKPT();
}
else
{
rc = btreeGetPage(pgno, ref ppPage, 0);
if (rc == RC.OK)
{
rc = ppPage.btreeInitPage();
if (rc != RC.OK)
{
ppPage.releasePage();
}
}
}
Debug.Assert(pgno != 0 || rc == RC.CORRUPT);
return(rc);
}
// was:fetchPayload
private RC AccessPayload(uint offset, uint size, byte[] b, bool writeOperation)
{
var page = Pages[PageID]; // Btree page of current entry
Debug.Assert(page != null);
Debug.Assert(State == CursorState.VALID);
Debug.Assert(PagesIndexs[PageID] < page.Cells);
Debug.Assert(HoldsMutex());
GetCellInfo();
var payload = Info.Cells;
var nKey = (uint)(page.HasIntKey ? 0 : (int)Info.nKey);
var shared = Shared; // Btree this cursor belongs to
if (Check.NEVER(offset + size > nKey + Info.nData) || Info.nLocal > shared.UsableSize)
{
// Trying to read or write past the end of the data is an error
return(SysEx.SQLITE_CORRUPT_BKPT());
}
// Check if data must be read/written to/from the btree page itself.
var rc = RC.OK;
uint bOffset = 0;
if (offset < Info.nLocal)
{
var a = (int)size;
if (a + offset > Info.nLocal)
{
a = (int)(Info.nLocal - offset);
}
rc = CopyPayload(page.DbPage, payload, (uint)(offset + Info.CellID + Info.nHeader), b, bOffset, (uint)a, writeOperation);
offset = 0;
bOffset += (uint)a;
size -= (uint)a;
}
else
{
offset -= Info.nLocal;
}
var iIdx = 0;
if (rc == RC.OK && size > 0)
{
var ovflSize = (uint)(shared.UsableSize - 4); // Bytes content per ovfl page
var nextPage = (Pgno)ConvertEx.Get4(payload, Info.nLocal + Info.CellID + Info.nHeader);
#if !SQLITE_OMIT_INCRBLOB
// If the isIncrblobHandle flag is set and the BtCursor.aOverflow[] has not been allocated, allocate it now. The array is sized at
// one entry for each overflow page in the overflow chain. The page number of the first overflow page is stored in aOverflow[0],
// etc. A value of 0 in the aOverflow[] array means "not yet known" (the cache is lazily populated).
if (IsIncrblob && OverflowIDs == null)
{
var nOvfl = (Info.nPayload - Info.nLocal + ovflSize - 1) / ovflSize;
OverflowIDs = new Pgno[nOvfl];
}
// If the overflow page-list cache has been allocated and the entry for the first required overflow page is valid, skip directly to it.
if (OverflowIDs != null && OverflowIDs[offset / ovflSize] != 0)
{
iIdx = (int)(offset / ovflSize);
nextPage = OverflowIDs[iIdx];
offset = (offset % ovflSize);
}
#endif
for (; rc == RC.OK && size > 0 && nextPage != 0; iIdx++)
{
#if !SQLITE_OMIT_INCRBLOB
// If required, populate the overflow page-list cache.
if (OverflowIDs != null)
{
Debug.Assert(OverflowIDs[iIdx] == 0 || OverflowIDs[iIdx] == nextPage);
OverflowIDs[iIdx] = nextPage;
}
#endif
MemPage MemPageDummy = null;
if (offset >= ovflSize)
{
// The only reason to read this page is to obtain the page number for the next page in the overflow chain. The page
// data is not required. So first try to lookup the overflow page-list cache, if any, then fall back to the getOverflowPage() function.
#if !SQLITE_OMIT_INCRBLOB
if (OverflowIDs != null && OverflowIDs[iIdx + 1] != 0)
{
nextPage = OverflowIDs[iIdx + 1];
}
else
#endif
rc = shared.getOverflowPage(nextPage, out MemPageDummy, out nextPage);
offset -= ovflSize;
}
else
{
// Need to read this page properly. It contains some of the range of data that is being read (eOp==null) or written (eOp!=null).
var pDbPage = new PgHdr();
var a = (int)size;
rc = shared.Pager.Get(nextPage, ref pDbPage);
if (rc == RC.OK)
{
payload = Pager.sqlite3PagerGetData(pDbPage);
nextPage = ConvertEx.Get4(payload);
if (a + offset > ovflSize)
{
a = (int)(ovflSize - offset);
}
rc = CopyPayload(pDbPage, payload, offset + 4, b, bOffset, (uint)a, writeOperation);
Pager.Unref(pDbPage);
offset = 0;
size -= (uint)a;
bOffset += (uint)a;
}
}
}
}
if (rc == RC.OK && size > 0)
{
return(SysEx.SQLITE_CORRUPT_BKPT());
}
return(rc);
}
internal static RC balance_nonroot(MemPage pParent, int iParentIdx, byte[] aOvflSpace, int isRoot)
{
var apOld = new MemPage[NB]; // pPage and up to two siblings
var apCopy = new MemPage[NB]; // Private copies of apOld[] pages
var apNew = new MemPage[NB + 2]; // pPage and up to NB siblings after balancing
var apDiv = new int[NB - 1]; // Divider cells in pParent
var cntNew = new int[NB + 2]; // Index in aCell[] of cell after i-th page
var szNew = new int[NB + 2]; // Combined size of cells place on i-th page
var szCell = new ushort[1]; // Local size of all cells in apCell[]
BtShared pBt; // The whole database
int nCell = 0; // Number of cells in apCell[]
int nMaxCells = 0; // Allocated size of apCell, szCell, aFrom.
int nNew = 0; // Number of pages in apNew[]
ushort leafCorrection; // 4 if pPage is a leaf. 0 if not
int leafData; // True if pPage is a leaf of a LEAFDATA tree
int usableSpace; // Bytes in pPage beyond the header
int pageFlags; // Value of pPage.aData[0]
int subtotal; // Subtotal of bytes in cells on one page
int iOvflSpace = 0; // First unused byte of aOvflSpace[]
//int szScratch; // Size of scratch memory requested
byte[][] apCell = null; // All cells begin balanced
//
pBt = pParent.Shared;
Debug.Assert(MutexEx.Held(pBt.Mutex));
Debug.Assert(Pager.IsPageWriteable(pParent.DbPage));
#if false
Btree.TRACE("BALANCE: begin page %d child of %d\n", pPage.pgno, pParent.pgno);
#endif
// At this point pParent may have at most one overflow cell. And if this overflow cell is present, it must be the cell with
// index iParentIdx. This scenario comes about when this function is called (indirectly) from sqlite3BtreeDelete().
Debug.Assert(pParent.NOverflows == 0 || pParent.NOverflows == 1);
Debug.Assert(pParent.NOverflows == 0 || pParent.Overflows[0].Index == iParentIdx);
// Find the sibling pages to balance. Also locate the cells in pParent that divide the siblings. An attempt is made to find NN siblings on
// either side of pPage. More siblings are taken from one side, however, if there are fewer than NN siblings on the other side. If pParent
// has NB or fewer children then all children of pParent are taken.
// This loop also drops the divider cells from the parent page. This way, the remainder of the function does not have to deal with any
// overflow cells in the parent page, since if any existed they will have already been removed.
int nOld; // Number of pages in apOld[]
int nxDiv; // Next divider slot in pParent.aCell[]
var i = pParent.NOverflows + pParent.Cells;
if (i < 2)
{
nxDiv = 0;
nOld = i + 1;
}
else
{
nOld = 3;
if (iParentIdx == 0)
{
nxDiv = 0;
}
else if (iParentIdx == i)
{
nxDiv = i - 2;
}
else
{
nxDiv = iParentIdx - 1;
}
i = 2;
}
var pRight = ((i + nxDiv - pParent.NOverflows) == pParent.Cells ? pParent.HeaderOffset + 8 : pParent.FindCell(i + nxDiv - pParent.NOverflows)); // Location in parent of right-sibling pointer
var pgno = (Pgno)ConvertEx.Get4(pParent.Data, pRight);
var rc = RC.OK;
while (true)
{
rc = pBt.getAndInitPage(pgno, ref apOld[i]);
if (rc != RC.OK)
{
goto balance_cleanup;
}
nMaxCells += 1 + apOld[i].Cells + apOld[i].NOverflows;
if (i-- == 0)
{
break;
}
if (i + nxDiv == pParent.Overflows[0].Index && pParent.NOverflows != 0)
{
apDiv[i] = 0;
pgno = ConvertEx.Get4(pParent.Overflows[0].Cell, apDiv[i]);
szNew[i] = pParent.cellSizePtr(apDiv[i]);
pParent.NOverflows = 0;
}
else
{
apDiv[i] = pParent.FindCell(i + nxDiv - pParent.NOverflows);
pgno = ConvertEx.Get4(pParent.Data, apDiv[i]);
szNew[i] = pParent.cellSizePtr(apDiv[i]);
// Drop the cell from the parent page. apDiv[i] still points to the cell within the parent, even though it has been dropped.
// This is safe because dropping a cell only overwrites the first four bytes of it, and this function does not need the first
// four bytes of the divider cell. So the pointer is safe to use later on.
//
// Unless SQLite is compiled in secure-delete mode. In this case, the dropCell() routine will overwrite the entire cell with zeroes.
// In this case, temporarily copy the cell into the aOvflSpace[] buffer. It will be copied out again as soon as the aSpace[] buffer
// is allocated.
//if (pBt.secureDelete)
//{
// int iOff = (int)(apDiv[i]) - (int)(pParent.aData); //SQLITE_PTR_TO_INT(apDiv[i]) - SQLITE_PTR_TO_INT(pParent.aData);
// if( (iOff+szNew[i])>(int)pBt->usableSize )
// {
// rc = SQLITE_CORRUPT_BKPT();
// Array.Clear(apOld[0].aData,0,apOld[0].aData.Length); //memset(apOld, 0, (i + 1) * sizeof(MemPage*));
// goto balance_cleanup;
// }
// else
// {
// memcpy(&aOvflSpace[iOff], apDiv[i], szNew[i]);
// apDiv[i] = &aOvflSpace[apDiv[i] - pParent.aData];
// }
//}
pParent.dropCell(i + nxDiv - pParent.NOverflows, szNew[i], ref rc);
}
}
// Make nMaxCells a multiple of 4 in order to preserve 8-byte alignment
nMaxCells = (nMaxCells + 3) & ~3;
// Allocate space for memory structures
apCell = MallocEx.sqlite3ScratchMalloc(apCell, nMaxCells);
if (szCell.Length < nMaxCells)
{
Array.Resize(ref szCell, nMaxCells);
}
// Load pointers to all cells on sibling pages and the divider cells into the local apCell[] array. Make copies of the divider cells
// into space obtained from aSpace1[] and remove the the divider Cells from pParent.
// If the siblings are on leaf pages, then the child pointers of the divider cells are stripped from the cells before they are copied
// into aSpace1[]. In this way, all cells in apCell[] are without child pointers. If siblings are not leaves, then all cell in
// apCell[] include child pointers. Either way, all cells in apCell[] are alike.
// leafCorrection: 4 if pPage is a leaf. 0 if pPage is not a leaf.
// leafData: 1 if pPage holds key+data and pParent holds only keys.
leafCorrection = (ushort)(apOld[0].Leaf * 4);
leafData = apOld[0].HasData;
int j;
for (i = 0; i < nOld; i++)
{
// Before doing anything else, take a copy of the i'th original sibling The rest of this function will use data from the copies rather
// that the original pages since the original pages will be in the process of being overwritten.
var pOld = apCopy[i] = apOld[i].Clone();
var limit = pOld.Cells + pOld.NOverflows;
if (pOld.NOverflows > 0 || true)
{
for (j = 0; j < limit; j++)
{
Debug.Assert(nCell < nMaxCells);
var iFOFC = pOld.FindOverflowCell(j);
szCell[nCell] = pOld.cellSizePtr(iFOFC);
// Copy the Data Locally
if (apCell[nCell] == null)
{
apCell[nCell] = new byte[szCell[nCell]];
}
else if (apCell[nCell].Length < szCell[nCell])
{
Array.Resize(ref apCell[nCell], szCell[nCell]);
}
if (iFOFC < 0) // Overflow Cell
{
Buffer.BlockCopy(pOld.Overflows[-(iFOFC + 1)].Cell, 0, apCell[nCell], 0, szCell[nCell]);
}
else
{
Buffer.BlockCopy(pOld.Data, iFOFC, apCell[nCell], 0, szCell[nCell]);
}
nCell++;
}
}
else
{
var aData = pOld.Data;
var maskPage = pOld.MaskPage;
var cellOffset = pOld.CellOffset;
for (j = 0; j < limit; j++)
{
Debugger.Break();
Debug.Assert(nCell < nMaxCells);
apCell[nCell] = FindCellv2(aData, maskPage, cellOffset, j);
szCell[nCell] = pOld.cellSizePtr(apCell[nCell]);
nCell++;
}
}
if (i < nOld - 1 && 0 == leafData)
{
var sz = (ushort)szNew[i];
var pTemp = MallocEx.sqlite3Malloc(sz + leafCorrection);
Debug.Assert(nCell < nMaxCells);
szCell[nCell] = sz;
Debug.Assert(sz <= pBt.MaxLocal + 23);
Buffer.BlockCopy(pParent.Data, apDiv[i], pTemp, 0, sz);
if (apCell[nCell] == null || apCell[nCell].Length < sz)
{
Array.Resize(ref apCell[nCell], sz);
}
Buffer.BlockCopy(pTemp, leafCorrection, apCell[nCell], 0, sz);
Debug.Assert(leafCorrection == 0 || leafCorrection == 4);
szCell[nCell] = (ushort)(szCell[nCell] - leafCorrection);
if (0 == pOld.Leaf)
{
Debug.Assert(leafCorrection == 0);
Debug.Assert(pOld.HeaderOffset == 0);
// The right pointer of the child page pOld becomes the left pointer of the divider cell
Buffer.BlockCopy(pOld.Data, 8, apCell[nCell], 0, 4);//memcpy( apCell[nCell], ref pOld.aData[8], 4 );
}
else
{
Debug.Assert(leafCorrection == 4);
if (szCell[nCell] < 4)
{
// Do not allow any cells smaller than 4 bytes.
szCell[nCell] = 4;
}
}
nCell++;
}
}
// Figure out the number of pages needed to hold all nCell cells. Store this number in "k". Also compute szNew[] which is the total
// size of all cells on the i-th page and cntNew[] which is the index in apCell[] of the cell that divides page i from page i+1.
// cntNew[k] should equal nCell.
// Values computed by this block:
// k: The total number of sibling pages
// szNew[i]: Spaced used on the i-th sibling page.
// cntNew[i]: Index in apCell[] and szCell[] for the first cell to
// the right of the i-th sibling page.
// usableSpace: Number of bytes of space available on each sibling.
usableSpace = (int)pBt.UsableSize - 12 + leafCorrection;
int k;
for (subtotal = k = i = 0; i < nCell; i++)
{
Debug.Assert(i < nMaxCells);
subtotal += szCell[i] + 2;
if (subtotal > usableSpace)
{
szNew[k] = subtotal - szCell[i];
cntNew[k] = i;
if (leafData != 0)
{
i--;
}
subtotal = 0;
k++;
if (k > NB + 1)
{
rc = SysEx.SQLITE_CORRUPT_BKPT();
goto balance_cleanup;
}
}
}
szNew[k] = subtotal;
cntNew[k] = nCell;
k++;
// The packing computed by the previous block is biased toward the siblings on the left side. The left siblings are always nearly full, while the
// right-most sibling might be nearly empty. This block of code attempts to adjust the packing of siblings to get a better balance.
//
// This adjustment is more than an optimization. The packing above might be so out of balance as to be illegal. For example, the right-most
// sibling might be completely empty. This adjustment is not optional.
for (i = k - 1; i > 0; i--)
{
var szRight = szNew[i]; // Size of sibling on the right
var szLeft = szNew[i - 1]; // Size of sibling on the left
var r = cntNew[i - 1] - 1; // Index of right-most cell in left sibling
var d = r + 1 - leafData; // Index of first cell to the left of right sibling
Debug.Assert(d < nMaxCells);
Debug.Assert(r < nMaxCells);
while (szRight == 0 || szRight + szCell[d] + 2 <= szLeft - (szCell[r] + 2))
{
szRight += szCell[d] + 2;
szLeft -= szCell[r] + 2;
cntNew[i - 1]--;
r = cntNew[i - 1] - 1;
d = r + 1 - leafData;
}
szNew[i] = szRight;
szNew[i - 1] = szLeft;
}
// Either we found one or more cells (cntnew[0])>0) or pPage is a virtual root page. A virtual root page is when the real root
// page is page 1 and we are the only child of that page.
Debug.Assert(cntNew[0] > 0 || (pParent.ID == 1 && pParent.Cells == 0));
Btree.TRACE("BALANCE: old: %d %d %d ", apOld[0].ID, (nOld >= 2 ? apOld[1].ID : 0), (nOld >= 3 ? apOld[2].ID : 0));
// Allocate k new pages. Reuse old pages where possible.
if (apOld[0].ID <= 1)
{
rc = SysEx.SQLITE_CORRUPT_BKPT();
goto balance_cleanup;
}
pageFlags = apOld[0].Data[0];
for (i = 0; i < k; i++)
{
var pNew = new MemPage();
if (i < nOld)
{
pNew = apNew[i] = apOld[i];
apOld[i] = null;
rc = Pager.Write(pNew.DbPage);
nNew++;
if (rc != RC.OK)
{
goto balance_cleanup;
}
}
else
{
Debug.Assert(i > 0);
rc = pBt.allocateBtreePage(ref pNew, ref pgno, pgno, 0);
if (rc != 0)
{
goto balance_cleanup;
}
apNew[i] = pNew;
nNew++;
// Set the pointer-map entry for the new sibling page.
#if !SQLITE_OMIT_AUTOVACUUM
if (pBt.AutoVacuum)
#else
if (false)
#endif
{
pBt.ptrmapPut(pNew.ID, PTRMAP.BTREE, pParent.ID, ref rc);
if (rc != RC.OK)
{
goto balance_cleanup;
}
}
}
}
// Free any old pages that were not reused as new pages.
while (i < nOld)
{
apOld[i].freePage(ref rc);
if (rc != RC.OK)
{
goto balance_cleanup;
}
apOld[i].releasePage();
apOld[i] = null;
i++;
}
// Put the new pages in accending order. This helps to keep entries in the disk file in order so that a scan
// of the table is a linear scan through the file. That in turn helps the operating system to deliver pages
// from the disk more rapidly.
// An O(n^2) insertion sort algorithm is used, but since n is never more than NB (a small constant), that should
// not be a problem.
// When NB==3, this one optimization makes the database about 25% faster for large insertions and deletions.
for (i = 0; i < k - 1; i++)
{
var minV = (int)apNew[i].ID;
var minI = i;
for (j = i + 1; j < k; j++)
{
if (apNew[j].ID < (uint)minV)
{
minI = j;
minV = (int)apNew[j].ID;
}
}
if (minI > i)
{
var pT = apNew[i];
apNew[i] = apNew[minI];
apNew[minI] = pT;
}
}
Btree.TRACE("new: %d(%d) %d(%d) %d(%d) %d(%d) %d(%d)\n", apNew[0].ID, szNew[0],
(nNew >= 2 ? apNew[1].ID : 0), (nNew >= 2 ? szNew[1] : 0),
(nNew >= 3 ? apNew[2].ID : 0), (nNew >= 3 ? szNew[2] : 0),
(nNew >= 4 ? apNew[3].ID : 0), (nNew >= 4 ? szNew[3] : 0),
(nNew >= 5 ? apNew[4].ID : 0), (nNew >= 5 ? szNew[4] : 0));
Debug.Assert(Pager.IsPageWriteable(pParent.DbPage));
ConvertEx.Put4L(pParent.Data, pRight, apNew[nNew - 1].ID);
// Evenly distribute the data in apCell[] across the new pages. Insert divider cells into pParent as necessary.
j = 0;
for (i = 0; i < nNew; i++)
{
// Assemble the new sibling page.
MemPage pNew = apNew[i];
Debug.Assert(j < nMaxCells);
pNew.zeroPage(pageFlags);
pNew.assemblePage(cntNew[i] - j, apCell, szCell, j);
Debug.Assert(pNew.Cells > 0 || (nNew == 1 && cntNew[0] == 0));
Debug.Assert(pNew.NOverflows == 0);
j = cntNew[i];
// If the sibling page assembled above was not the right-most sibling, insert a divider cell into the parent page.
Debug.Assert(i < nNew - 1 || j == nCell);
if (j < nCell)
{
Debug.Assert(j < nMaxCells);
var pCell = apCell[j];
var sz = szCell[j] + leafCorrection;
var pTemp = MallocEx.sqlite3Malloc(sz);
if (pNew.Leaf == 0)
{
Buffer.BlockCopy(pCell, 0, pNew.Data, 8, 4);
}
else if (leafData != 0)
{
// If the tree is a leaf-data tree, and the siblings are leaves, then there is no divider cell in apCell[]. Instead, the divider
// cell consists of the integer key for the right-most cell of the sibling-page assembled above only.
var info = new CellInfo();
j--;
pNew.btreeParseCellPtr(apCell[j], ref info);
pCell = pTemp;
sz = 4 + ConvertEx.PutVarint9L(pCell, 4, (ulong)info.nKey);
pTemp = null;
}
else
{
//------------ pCell -= 4;
var _pCell_4 = MallocEx.sqlite3Malloc(pCell.Length + 4);
Buffer.BlockCopy(pCell, 0, _pCell_4, 4, pCell.Length);
pCell = _pCell_4;
// Obscure case for non-leaf-data trees: If the cell at pCell was previously stored on a leaf node, and its reported size was 4
// bytes, then it may actually be smaller than this (see btreeParseCellPtr(), 4 bytes is the minimum size of
// any cell). But it is important to pass the correct size to insertCell(), so reparse the cell now.
// Note that this can never happen in an SQLite data file, as all cells are at least 4 bytes. It only happens in b-trees used
// to evaluate "IN (SELECT ...)" and similar clauses.
if (szCell[j] == 4)
{
Debug.Assert(leafCorrection == 4);
sz = pParent.cellSizePtr(pCell);
}
}
iOvflSpace += sz;
Debug.Assert(sz <= pBt.MaxLocal + 23);
Debug.Assert(iOvflSpace <= (int)pBt.PageSize);
pParent.insertCell(nxDiv, pCell, sz, pTemp, pNew.ID, ref rc);
if (rc != RC.OK)
{
goto balance_cleanup;
}
Debug.Assert(Pager.IsPageWriteable(pParent.DbPage));
j++;
nxDiv++;
}
}
Debug.Assert(j == nCell);
Debug.Assert(nOld > 0);
Debug.Assert(nNew > 0);
if ((pageFlags & Btree.PTF_LEAF) == 0)
{
Buffer.BlockCopy(apCopy[nOld - 1].Data, 8, apNew[nNew - 1].Data, 8, 4);
}
if (isRoot != 0 && pParent.Cells == 0 && pParent.HeaderOffset <= apNew[0].FreeBytes)
{
// The root page of the b-tree now contains no cells. The only sibling page is the right-child of the parent. Copy the contents of the
// child page into the parent, decreasing the overall height of the b-tree structure by one. This is described as the "balance-shallower"
// sub-algorithm in some documentation.
// If this is an auto-vacuum database, the call to copyNodeContent() sets all pointer-map entries corresponding to database image pages
// for which the pointer is stored within the content being copied.
// The second Debug.Assert below verifies that the child page is defragmented (it must be, as it was just reconstructed using assemblePage()). This
// is important if the parent page happens to be page 1 of the database image. */
Debug.Assert(nNew == 1);
Debug.Assert(apNew[0].FreeBytes == (ConvertEx.Get2(apNew[0].Data, 5) - apNew[0].CellOffset - apNew[0].Cells * 2));
copyNodeContent(apNew[0], pParent, ref rc);
apNew[0].freePage(ref rc);
}
else
#if !SQLITE_OMIT_AUTOVACUUM
if (pBt.AutoVacuum)
#else
if (false)
#endif
{
// Fix the pointer-map entries for all the cells that were shifted around. There are several different types of pointer-map entries that need to
// be dealt with by this routine. Some of these have been set already, but many have not. The following is a summary:
// 1) The entries associated with new sibling pages that were not siblings when this function was called. These have already
// been set. We don't need to worry about old siblings that were moved to the free-list - the freePage() code has taken care
// of those.
// 2) The pointer-map entries associated with the first overflow page in any overflow chains used by new divider cells. These
// have also already been taken care of by the insertCell() code.
// 3) If the sibling pages are not leaves, then the child pages of cells stored on the sibling pages may need to be updated.
// 4) If the sibling pages are not internal intkey nodes, then any overflow pages used by these cells may need to be updated
// (internal intkey nodes never contain pointers to overflow pages).
// 5) If the sibling pages are not leaves, then the pointer-map entries for the right-child pages of each sibling may need
// to be updated.
// Cases 1 and 2 are dealt with above by other code. The next block deals with cases 3 and 4 and the one after that, case 5. Since
// setting a pointer map entry is a relatively expensive operation, this code only sets pointer map entries for child or overflow pages that have
// actually moved between pages.
var pNew = apNew[0];
var pOld = apCopy[0];
var nOverflow = pOld.NOverflows;
var iNextOld = pOld.Cells + nOverflow;
var iOverflow = (nOverflow != 0 ? pOld.Overflows[0].Index : -1);
j = 0; // Current 'old' sibling page
k = 0; // Current 'new' sibling page
for (i = 0; i < nCell; i++)
{
var isDivider = 0;
while (i == iNextOld)
{
// Cell i is the cell immediately following the last cell on old sibling page j. If the siblings are not leaf pages of an
// intkey b-tree, then cell i was a divider cell.
pOld = apCopy[++j];
iNextOld = i + (0 == leafData ? 1 : 0) + pOld.Cells + pOld.NOverflows;
if (pOld.NOverflows != 0)
{
nOverflow = pOld.NOverflows;
iOverflow = i + (0 == leafData ? 1 : 0) + pOld.Overflows[0].Index;
}
isDivider = 0 == leafData ? 1 : 0;
}
Debug.Assert(nOverflow > 0 || iOverflow < i);
Debug.Assert(nOverflow < 2 || pOld.Overflows[0].Index == pOld.Overflows[1].Index - 1);
Debug.Assert(nOverflow < 3 || pOld.Overflows[1].Index == pOld.Overflows[2].Index - 1);
if (i == iOverflow)
{
isDivider = 1;
if (--nOverflow > 0)
{
iOverflow++;
}
}
if (i == cntNew[k])
{
// Cell i is the cell immediately following the last cell on new sibling page k. If the siblings are not leaf pages of an
// intkey b-tree, then cell i is a divider cell.
pNew = apNew[++k];
if (leafData == 0)
{
continue;
}
}
Debug.Assert(j < nOld);
Debug.Assert(k < nNew);
// If the cell was originally divider cell (and is not now) or an overflow cell, or if the cell was located on a different sibling
// page before the balancing, then the pointer map entries associated with any child or overflow pages need to be updated.
if (isDivider != 0 || pOld.ID != pNew.ID)
{
if (leafCorrection == 0)
{
pBt.ptrmapPut(ConvertEx.Get4(apCell[i]), PTRMAP.BTREE, pNew.ID, ref rc);
}
if (szCell[i] > pNew.MinLocal)
{
pNew.ptrmapPutOvflPtr(apCell[i], ref rc);
}
}
}
if (leafCorrection == 0)
{
for (i = 0; i < nNew; i++)
{
var key = ConvertEx.Get4(apNew[i].Data, 8);
pBt.ptrmapPut(key, PTRMAP.BTREE, apNew[i].ID, ref rc);
}
}
#if false
// The ptrmapCheckPages() contains Debug.Assert() statements that verify that all pointer map pages are set correctly. This is helpful while
// debugging. This is usually disabled because a corrupt database may cause an Debug.Assert() statement to fail.
ptrmapCheckPages(apNew, nNew);
ptrmapCheckPages(pParent, 1);
#endif
}
Debug.Assert(pParent.HasInit);
Btree.TRACE("BALANCE: finished: old=%d new=%d cells=%d\n", nOld, nNew, nCell);
// Cleanup before returning.
balance_cleanup:
MallocEx.sqlite3ScratchFree(apCell);
for (i = 0; i < nOld; i++)
{
apOld[i].releasePage();
}
for (i = 0; i < nNew; i++)
{
apNew[i].releasePage();
}
return(rc);
}
internal static void assertParentIndex(MemPage pParent, int iIdx, Pgno iChild)
{
Debug.Assert(iIdx <= pParent.Cells);
if (iIdx == pParent.Cells)
Debug.Assert(ConvertEx.Get4(pParent.Data, pParent.HeaderOffset + 8) == iChild);
else
Debug.Assert(ConvertEx.Get4(pParent.Data, pParent.FindCell(iIdx)) == iChild);
}
internal RC allocateBtreePage(ref MemPage ppPage, ref Pgno pPgno, Pgno nearby, byte exact)
{
MemPage pTrunk = null;
MemPage pPrevTrunk = null;
Debug.Assert(MutexEx.Held(this.Mutex));
var pPage1 = this.Page1;
var mxPage = btreePagecount(); // Total size of the database file
var n = ConvertEx.Get4(pPage1.Data, 36); // Number of pages on the freelist
if (n >= mxPage)
{
return(SysEx.SQLITE_CORRUPT_BKPT());
}
RC rc;
if (n > 0)
{
// There are pages on the freelist. Reuse one of those pages.
Pgno iTrunk;
byte searchList = 0; // If the free-list must be searched for 'nearby'
// If the 'exact' parameter was true and a query of the pointer-map shows that the page 'nearby' is somewhere on the free-list, then the entire-list will be searched for that page.
#if !SQLITE_OMIT_AUTOVACUUM
if (exact != 0 && nearby <= mxPage)
{
Debug.Assert(nearby > 0);
Debug.Assert(this.AutoVacuum);
PTRMAP eType = 0;
uint dummy0 = 0;
rc = ptrmapGet(nearby, ref eType, ref dummy0);
if (rc != RC.OK)
{
return(rc);
}
if (eType == PTRMAP.FREEPAGE)
{
searchList = 1;
}
pPgno = nearby;
}
#endif
// Decrement the free-list count by 1. Set iTrunk to the index of the first free-list trunk page. iPrevTrunk is initially 1.
rc = Pager.Write(pPage1.DbPage);
if (rc != RC.OK)
{
return(rc);
}
ConvertEx.Put4(pPage1.Data, 36, n - 1);
// The code within this loop is run only once if the 'searchList' variable is not true. Otherwise, it runs once for each trunk-page on the
// free-list until the page 'nearby' is located.
do
{
pPrevTrunk = pTrunk;
iTrunk = (pPrevTrunk != null ? ConvertEx.Get4(pPrevTrunk.Data, 0) : ConvertEx.Get4(pPage1.Data, 32));
rc = (iTrunk > mxPage ? SysEx.SQLITE_CORRUPT_BKPT() : btreeGetPage(iTrunk, ref pTrunk, 0));
if (rc != RC.OK)
{
pTrunk = null;
goto end_allocate_page;
}
var k = ConvertEx.Get4(pTrunk.Data, 4); // # of leaves on this trunk page
if (k == 0 && searchList == 0)
{
// The trunk has no leaves and the list is not being searched. So extract the trunk page itself and use it as the newly allocated page
Debug.Assert(pPrevTrunk == null);
rc = Pager.Write(pTrunk.DbPage);
if (rc != RC.OK)
{
goto end_allocate_page;
}
pPgno = iTrunk;
Buffer.BlockCopy(pTrunk.Data, 0, pPage1.Data, 32, 4);
ppPage = pTrunk;
pTrunk = null;
Btree.TRACE("ALLOCATE: %d trunk - %d free pages left\n", pPgno, n - 1);
}
else if (k > (uint)(this.UsableSize / 4 - 2))
{
// Value of k is out of range. Database corruption
rc = SysEx.SQLITE_CORRUPT_BKPT();
goto end_allocate_page;
#if !SQLITE_OMIT_AUTOVACUUM
}
else if (searchList != 0 && nearby == iTrunk)
{
// The list is being searched and this trunk page is the page to allocate, regardless of whether it has leaves.
Debug.Assert(pPgno == iTrunk);
ppPage = pTrunk;
searchList = 0;
rc = Pager.Write(pTrunk.DbPage);
if (rc != RC.OK)
{
goto end_allocate_page;
}
if (k == 0)
{
if (pPrevTrunk == null)
{
pPage1.Data[32 + 0] = pTrunk.Data[0 + 0];
pPage1.Data[32 + 1] = pTrunk.Data[0 + 1];
pPage1.Data[32 + 2] = pTrunk.Data[0 + 2];
pPage1.Data[32 + 3] = pTrunk.Data[0 + 3];
}
else
{
rc = Pager.Write(pPrevTrunk.DbPage);
if (rc != RC.OK)
{
goto end_allocate_page;
}
pPrevTrunk.Data[0 + 0] = pTrunk.Data[0 + 0];
pPrevTrunk.Data[0 + 1] = pTrunk.Data[0 + 1];
pPrevTrunk.Data[0 + 2] = pTrunk.Data[0 + 2];
pPrevTrunk.Data[0 + 3] = pTrunk.Data[0 + 3];
}
}
else
{
// The trunk page is required by the caller but it contains pointers to free-list leaves. The first leaf becomes a trunk page in this case.
var pNewTrunk = new MemPage();
var iNewTrunk = (Pgno)ConvertEx.Get4(pTrunk.Data, 8);
if (iNewTrunk > mxPage)
{
rc = SysEx.SQLITE_CORRUPT_BKPT();
goto end_allocate_page;
}
rc = btreeGetPage(iNewTrunk, ref pNewTrunk, 0);
if (rc != RC.OK)
{
goto end_allocate_page;
}
rc = Pager.Write(pNewTrunk.DbPage);
if (rc != RC.OK)
{
pNewTrunk.releasePage();
goto end_allocate_page;
}
pNewTrunk.Data[0 + 0] = pTrunk.Data[0 + 0];
pNewTrunk.Data[0 + 1] = pTrunk.Data[0 + 1];
pNewTrunk.Data[0 + 2] = pTrunk.Data[0 + 2];
pNewTrunk.Data[0 + 3] = pTrunk.Data[0 + 3];
ConvertEx.Put4(pNewTrunk.Data, 4, (uint)(k - 1));
Buffer.BlockCopy(pTrunk.Data, 12, pNewTrunk.Data, 8, (int)(k - 1) * 4);
pNewTrunk.releasePage();
if (pPrevTrunk == null)
{
Debug.Assert(Pager.IsPageWriteable(pPage1.DbPage));
ConvertEx.Put4(pPage1.Data, 32, iNewTrunk);
}
else
{
rc = Pager.Write(pPrevTrunk.DbPage);
if (rc != RC.OK)
{
goto end_allocate_page;
}
ConvertEx.Put4(pPrevTrunk.Data, 0, iNewTrunk);
}
}
pTrunk = null;
Btree.TRACE("ALLOCATE: %d trunk - %d free pages left\n", pPgno, n - 1);
#endif
}
else if (k > 0)
{
// Extract a leaf from the trunk
uint closest;
var aData = pTrunk.Data;
if (nearby > 0)
{
closest = 0;
var dist = Math.Abs((int)(ConvertEx.Get4(aData, 8) - nearby));
for (uint i = 1; i < k; i++)
{
int dist2 = Math.Abs((int)(ConvertEx.Get4(aData, 8 + i * 4) - nearby));
if (dist2 < dist)
{
closest = i;
dist = dist2;
}
}
}
else
{
closest = 0;
}
//
var iPage = (Pgno)ConvertEx.Get4(aData, 8 + closest * 4);
if (iPage > mxPage)
{
rc = SysEx.SQLITE_CORRUPT_BKPT();
goto end_allocate_page;
}
if (searchList == 0 || iPage == nearby)
{
pPgno = iPage;
Btree.TRACE("ALLOCATE: %d was leaf %d of %d on trunk %d" + ": %d more free pages\n", pPgno, closest + 1, k, pTrunk.ID, n - 1);
rc = Pager.Write(pTrunk.DbPage);
if (rc != RC.OK)
{
goto end_allocate_page;
}
if (closest < k - 1)
{
Buffer.BlockCopy(aData, (int)(4 + k * 4), aData, 8 + (int)closest * 4, 4);
}
ConvertEx.Put4(aData, 4, (k - 1));
var noContent = (!btreeGetHasContent(pPgno) ? 1 : 0);
rc = btreeGetPage(pPgno, ref ppPage, noContent);
if (rc == RC.OK)
{
rc = Pager.Write((ppPage).DbPage);
if (rc != RC.OK)
{
ppPage.releasePage();
}
}
searchList = 0;
}
}
pPrevTrunk.releasePage();
pPrevTrunk = null;
} while (searchList != 0);
}
else
{
// There are no pages on the freelist, so create a new page at the end of the file
rc = Pager.Write(this.Page1.DbPage);
if (rc != RC.OK)
{
return(rc);
}
this.Pages++;
if (this.Pages == MemPage.PENDING_BYTE_PAGE(this))
{
this.Pages++;
}
#if !SQLITE_OMIT_AUTOVACUUM
if (this.AutoVacuum && MemPage.PTRMAP_ISPAGE(this, this.Pages))
{
// If pPgno refers to a pointer-map page, allocate two new pages at the end of the file instead of one. The first allocated page
// becomes a new pointer-map page, the second is used by the caller.
MemPage pPg = null;
Btree.TRACE("ALLOCATE: %d from end of file (pointer-map page)\n", pPgno);
Debug.Assert(this.Pages != MemPage.PENDING_BYTE_PAGE(this));
rc = btreeGetPage(this.Pages, ref pPg, 1);
if (rc == RC.OK)
{
rc = Pager.Write(pPg.DbPage);
pPg.releasePage();
}
if (rc != RC.OK)
{
return(rc);
}
this.Pages++;
if (this.Pages == MemPage.PENDING_BYTE_PAGE(this))
{
this.Pages++;
}
}
#endif
ConvertEx.Put4(this.Page1.Data, 28, this.Pages);
pPgno = this.Pages;
Debug.Assert(pPgno != MemPage.PENDING_BYTE_PAGE(this));
rc = btreeGetPage(pPgno, ref ppPage, 1);
if (rc != RC.OK)
{
return(rc);
}
rc = Pager.Write((ppPage).DbPage);
if (rc != RC.OK)
{
ppPage.releasePage();
}
Btree.TRACE("ALLOCATE: %d from end of file\n", pPgno);
}
Debug.Assert(pPgno != MemPage.PENDING_BYTE_PAGE(this));
end_allocate_page:
pTrunk.releasePage();
pPrevTrunk.releasePage();
if (rc == RC.OK)
{
if (Pager.GetPageRefCount((ppPage).DbPage) > 1)
{
ppPage.releasePage();
return(SysEx.SQLITE_CORRUPT_BKPT());
}
(ppPage).HasInit = false;
}
else
{
ppPage = null;
}
Debug.Assert(rc != RC.OK || Pager.IsPageWriteable((ppPage).DbPage));
return(rc);
}
internal RC lockBtree()
{
Debug.Assert(MutexEx.Held(this.Mutex));
Debug.Assert(this.Page1 == null);
var rc = this.Pager.SharedLock();
if (rc != RC.OK)
{
return(rc);
}
MemPage pPage1 = null; // Page 1 of the database file
rc = btreeGetPage(1, ref pPage1, 0);
if (rc != RC.OK)
{
return(rc);
}
// Do some checking to help insure the file we opened really is a valid database file.
Pgno nPageHeader; // Number of pages in the database according to hdr
var nPage = nPageHeader = ConvertEx.Get4(pPage1.Data, 28); // Number of pages in the database
Pgno nPageFile; // Number of pages in the database file
this.Pager.GetPageCount(out nPageFile);
if (nPage == 0 || ArrayEx.Compare(pPage1.Data, 24, pPage1.Data, 92, 4) != 0)
{
nPage = nPageFile;
}
if (nPage > 0)
{
var page1 = pPage1.Data;
rc = RC.NOTADB;
if (ArrayEx.Compare(page1, Btree.zMagicHeader, 16) != 0)
{
goto page1_init_failed;
}
#if SQLITE_OMIT_WAL
if (page1[18] > 1)
{
this.ReadOnly = true;
}
if (page1[19] > 1)
{
this.Schema.file_format = page1[19];
goto page1_init_failed;
}
#else
if (page1[18] > 2)
{
pBt.readOnly = true;
}
if (page1[19] > 2)
{
goto page1_init_failed;
}
/* If the write version is set to 2, this database should be accessed
** in WAL mode. If the log is not already open, open it now. Then
** return SQLITE_OK and return without populating BtShared.pPage1.
** The caller detects this and calls this function again. This is
** required as the version of page 1 currently in the page1 buffer
** may not be the latest version - there may be a newer one in the log
** file.
*/
if (page1[19] == 2 && pBt.doNotUseWAL == false)
{
int isOpen = 0;
rc = sqlite3PagerOpenWal(pBt.pPager, ref isOpen);
if (rc != SQLITE_OK)
{
goto page1_init_failed;
}
else if (isOpen == 0)
{
releasePage(pPage1);
return(SQLITE_OK);
}
rc = SQLITE_NOTADB;
}
#endif
// The maximum embedded fraction must be exactly 25%. And the minimum embedded fraction must be 12.5% for both leaf-data and non-leaf-data.
// The original design allowed these amounts to vary, but as of version 3.6.0, we require them to be fixed.
if (ArrayEx.Compare(page1, 21, "\x0040\x0020\x0020", 3) != 0) // "\100\040\040"
{
goto page1_init_failed;
}
var pageSize = (uint)((page1[16] << 8) | (page1[17] << 16));
if (((pageSize - 1) & pageSize) != 0 || pageSize > Pager.SQLITE_MAX_PAGE_SIZE || pageSize <= 256)
{
goto page1_init_failed;
}
Debug.Assert((pageSize & 7) == 0);
var usableSize = pageSize - page1[20];
if (pageSize != this.PageSize)
{
// After reading the first page of the database assuming a page size of BtShared.pageSize, we have discovered that the page-size is
// actually pageSize. Unlock the database, leave pBt.pPage1 at zero and return SQLITE_OK. The caller will call this function
// again with the correct page-size.
pPage1.releasePage();
this.UsableSize = usableSize;
this.PageSize = pageSize;
rc = this.Pager.SetPageSize(ref this.PageSize, (int)(pageSize - usableSize));
return(rc);
}
if ((this.DB.flags & sqlite3b.SQLITE.RecoveryMode) == 0 && nPage > nPageFile)
{
rc = SysEx.SQLITE_CORRUPT_BKPT();
goto page1_init_failed;
}
if (usableSize < 480)
{
goto page1_init_failed;
}
this.PageSize = pageSize;
this.UsableSize = usableSize;
#if !SQLITE_OMIT_AUTOVACUUM
this.AutoVacuum = (ConvertEx.Get4(page1, 36 + 4 * 4) != 0);
this.IncrVacuum = (ConvertEx.Get4(page1, 36 + 7 * 4) != 0);
#endif
}
// maxLocal is the maximum amount of payload to store locally for a cell. Make sure it is small enough so that at least minFanout
// cells can will fit on one page. We assume a 10-byte page header. Besides the payload, the cell must store:
// 2-byte pointer to the cell
// 4-byte child pointer
// 9-byte nKey value
// 4-byte nData value
// 4-byte overflow page pointer
// So a cell consists of a 2-byte pointer, a header which is as much as 17 bytes long, 0 to N bytes of payload, and an optional 4 byte overflow page pointer.
this.MaxLocal = (ushort)((this.UsableSize - 12) * 64 / 255 - 23);
this.MinLocal = (ushort)((this.UsableSize - 12) * 32 / 255 - 23);
this.MaxLeaf = (ushort)(this.UsableSize - 35);
this.MinLeaf = (ushort)((this.UsableSize - 12) * 32 / 255 - 23);
Debug.Assert(this.MaxLeaf + 23 <= Btree.MX_CELL_SIZE(this));
this.Page1 = pPage1;
this.Pages = nPage;
return(RC.OK);
page1_init_failed:
pPage1.releasePage();
this.Page1 = null;
return(rc);
}
internal static RC relocatePage(BtShared pBt, MemPage pDbPage, PTRMAP eType, Pgno iPtrPage, Pgno iFreePage, int isCommit)
{
var pPtrPage = new MemPage(); // The page that contains a pointer to pDbPage
var iDbPage = pDbPage.ID;
var pPager = pBt.Pager;
Debug.Assert(eType == PTRMAP.OVERFLOW2 || eType == PTRMAP.OVERFLOW1 || eType == PTRMAP.BTREE || eType == PTRMAP.ROOTPAGE);
Debug.Assert(MutexEx.Held(pBt.Mutex));
Debug.Assert(pDbPage.Shared == pBt);
// Move page iDbPage from its current location to page number iFreePage
Btree.TRACE("AUTOVACUUM: Moving %d to free page %d (ptr page %d type %d)\n", iDbPage, iFreePage, iPtrPage, eType);
var rc = pPager.sqlite3PagerMovepage(pDbPage.DbPage, iFreePage, isCommit);
if (rc != RC.OK)
{
return(rc);
}
pDbPage.ID = iFreePage;
// If pDbPage was a btree-page, then it may have child pages and/or cells that point to overflow pages. The pointer map entries for all these
// pages need to be changed.
// If pDbPage is an overflow page, then the first 4 bytes may store a pointer to a subsequent overflow page. If this is the case, then
// the pointer map needs to be updated for the subsequent overflow page.
if (eType == PTRMAP.BTREE || eType == PTRMAP.ROOTPAGE)
{
rc = pDbPage.setChildPtrmaps();
if (rc != RC.OK)
{
return(rc);
}
}
else
{
var nextOvfl = (Pgno)ConvertEx.Get4(pDbPage.Data);
if (nextOvfl != 0)
{
pBt.ptrmapPut(nextOvfl, PTRMAP.OVERFLOW2, iFreePage, ref rc);
if (rc != RC.OK)
{
return(rc);
}
}
}
// Fix the database pointer on page iPtrPage that pointed at iDbPage so that it points at iFreePage. Also fix the pointer map entry for iPtrPage.
if (eType != PTRMAP.ROOTPAGE)
{
rc = pBt.btreeGetPage(iPtrPage, ref pPtrPage, 0);
if (rc != RC.OK)
{
return(rc);
}
rc = Pager.Write(pPtrPage.DbPage);
if (rc != RC.OK)
{
pPtrPage.releasePage();
return(rc);
}
rc = pPtrPage.modifyPagePointer(iDbPage, iFreePage, eType);
pPtrPage.releasePage();
if (rc == RC.OK)
{
pBt.ptrmapPut(iFreePage, eType, iPtrPage, ref rc);
}
}
return(rc);
}
internal RC freePage2(MemPage pMemPage, Pgno iPage)
{
MemPage pTrunk = null; // Free-list trunk page
var pPage1 = this.Page1; // Local reference to page 1
Debug.Assert(MutexEx.Held(this.Mutex));
Debug.Assert(iPage > 1);
Debug.Assert(pMemPage == null || pMemPage.ID == iPage);
MemPage pPage; // Page being freed. May be NULL.
if (pMemPage != null)
{
pPage = pMemPage;
Pager.AddPageRef(pPage.DbPage);
}
else
pPage = btreePageLookup(iPage);
// Increment the free page count on pPage1
var rc = Pager.Write(pPage1.DbPage);
if (rc != RC.OK)
goto freepage_out;
var nFree = (int)ConvertEx.Get4(pPage1.Data, 36); // Initial number of pages on free-list
ConvertEx.Put4(pPage1.Data, 36, nFree + 1);
if (this.SecureDelete)
{
// If the secure_delete option is enabled, then always fully overwrite deleted information with zeros.
if ((pPage == null && ((rc = btreeGetPage(iPage, ref pPage, 0)) != RC.OK)) || ((rc = Pager.Write(pPage.DbPage)) != RC.OK))
goto freepage_out;
Array.Clear(pPage.Data, 0, (int)pPage.Shared.PageSize);
}
// If the database supports auto-vacuum, write an entry in the pointer-map to indicate that the page is free.
#if !SQLITE_OMIT_AUTOVACUUM
if (this.AutoVacuum)
#else
if (false)
#endif
{
ptrmapPut(iPage, PTRMAP.FREEPAGE, 0, ref rc);
if (rc != RC.OK)
goto freepage_out;
}
// Now manipulate the actual database free-list structure. There are two possibilities. If the free-list is currently empty, or if the first
// trunk page in the free-list is full, then this page will become a new free-list trunk page. Otherwise, it will become a leaf of the
// first trunk page in the current free-list. This block tests if it is possible to add the page as a new free-list leaf.
Pgno iTrunk = 0; // Page number of free-list trunk page
if (nFree != 0)
{
uint nLeaf; // Initial number of leaf cells on trunk page
iTrunk = (Pgno)ConvertEx.Get4(pPage1.Data, 32); // Page number of free-list trunk page
rc = btreeGetPage(iTrunk, ref pTrunk, 0);
if (rc != RC.OK)
goto freepage_out;
nLeaf = ConvertEx.Get4(pTrunk.Data, 4);
Debug.Assert(this.UsableSize > 32);
if (nLeaf > (uint)this.UsableSize / 4 - 2)
{
rc = SysEx.SQLITE_CORRUPT_BKPT();
goto freepage_out;
}
if (nLeaf < (uint)this.UsableSize / 4 - 8)
{
// In this case there is room on the trunk page to insert the page being freed as a new leaf.
// Note: that the trunk page is not really full until it contains usableSize/4 - 2 entries, not usableSize/4 - 8 entries as we have
// coded. But due to a coding error in versions of SQLite prior to 3.6.0, databases with freelist trunk pages holding more than
// usableSize/4 - 8 entries will be reported as corrupt. In order to maintain backwards compatibility with older versions of SQLite,
// we will continue to restrict the number of entries to usableSize/4 - 8 for now. At some point in the future (once everyone has upgraded
// to 3.6.0 or later) we should consider fixing the conditional above to read "usableSize/4-2" instead of "usableSize/4-8".
rc = Pager.Write(pTrunk.DbPage);
if (rc == RC.OK)
{
ConvertEx.Put4(pTrunk.Data, 4, nLeaf + 1);
ConvertEx.Put4(pTrunk.Data, (uint)(8 + nLeaf * 4), iPage);
if (pPage != null && !this.SecureDelete)
Pager.DontWrite(pPage.DbPage);
rc = btreeSetHasContent(iPage);
}
Btree.TRACE("FREE-PAGE: %d leaf on trunk page %d\n", iPage, pTrunk.ID);
goto freepage_out;
}
}
// If control flows to this point, then it was not possible to add the the page being freed as a leaf page of the first trunk in the free-list.
// Possibly because the free-list is empty, or possibly because the first trunk in the free-list is full. Either way, the page being freed
// will become the new first trunk page in the free-list.
if (pPage == null && (rc = btreeGetPage(iPage, ref pPage, 0)) != RC.OK)
goto freepage_out;
rc = Pager.Write(pPage.DbPage);
if (rc != RC.OK)
goto freepage_out;
ConvertEx.Put4L(pPage.Data, iTrunk);
ConvertEx.Put4(pPage.Data, 4, 0);
ConvertEx.Put4(pPage1.Data, 32, iPage);
Btree.TRACE("FREE-PAGE: %d new trunk page replacing %d\n", pPage.ID, iTrunk);
freepage_out:
if (pPage != null)
pPage.HasInit = false;
pPage.releasePage();
pTrunk.releasePage();
return rc;
}
internal static RC relocatePage(BtShared pBt, MemPage pDbPage, PTRMAP eType, Pgno iPtrPage, Pgno iFreePage, int isCommit)
{
var pPtrPage = new MemPage(); // The page that contains a pointer to pDbPage
var iDbPage = pDbPage.ID;
var pPager = pBt.Pager;
Debug.Assert(eType == PTRMAP.OVERFLOW2 || eType == PTRMAP.OVERFLOW1 || eType == PTRMAP.BTREE || eType == PTRMAP.ROOTPAGE);
Debug.Assert(MutexEx.Held(pBt.Mutex));
Debug.Assert(pDbPage.Shared == pBt);
// Move page iDbPage from its current location to page number iFreePage
Btree.TRACE("AUTOVACUUM: Moving %d to free page %d (ptr page %d type %d)\n", iDbPage, iFreePage, iPtrPage, eType);
var rc = pPager.sqlite3PagerMovepage(pDbPage.DbPage, iFreePage, isCommit);
if (rc != RC.OK)
return rc;
pDbPage.ID = iFreePage;
// If pDbPage was a btree-page, then it may have child pages and/or cells that point to overflow pages. The pointer map entries for all these
// pages need to be changed.
// If pDbPage is an overflow page, then the first 4 bytes may store a pointer to a subsequent overflow page. If this is the case, then
// the pointer map needs to be updated for the subsequent overflow page.
if (eType == PTRMAP.BTREE || eType == PTRMAP.ROOTPAGE)
{
rc = pDbPage.setChildPtrmaps();
if (rc != RC.OK)
return rc;
}
else
{
var nextOvfl = (Pgno)ConvertEx.Get4(pDbPage.Data);
if (nextOvfl != 0)
{
pBt.ptrmapPut(nextOvfl, PTRMAP.OVERFLOW2, iFreePage, ref rc);
if (rc != RC.OK)
return rc;
}
}
// Fix the database pointer on page iPtrPage that pointed at iDbPage so that it points at iFreePage. Also fix the pointer map entry for iPtrPage.
if (eType != PTRMAP.ROOTPAGE)
{
rc = pBt.btreeGetPage(iPtrPage, ref pPtrPage, 0);
if (rc != RC.OK)
return rc;
rc = Pager.Write(pPtrPage.DbPage);
if (rc != RC.OK)
{
pPtrPage.releasePage();
return rc;
}
rc = pPtrPage.modifyPagePointer(iDbPage, iFreePage, eType);
pPtrPage.releasePage();
if (rc == RC.OK)
pBt.ptrmapPut(iFreePage, eType, iPtrPage, ref rc);
}
return rc;
}
internal RC allocateBtreePage(ref MemPage ppPage, ref Pgno pPgno, Pgno nearby, byte exact)
{
MemPage pTrunk = null;
MemPage pPrevTrunk = null;
Debug.Assert(MutexEx.Held(this.Mutex));
var pPage1 = this.Page1;
var mxPage = btreePagecount(); // Total size of the database file
var n = ConvertEx.Get4(pPage1.Data, 36); // Number of pages on the freelist
if (n >= mxPage)
return SysEx.SQLITE_CORRUPT_BKPT();
RC rc;
if (n > 0)
{
// There are pages on the freelist. Reuse one of those pages.
Pgno iTrunk;
byte searchList = 0; // If the free-list must be searched for 'nearby'
// If the 'exact' parameter was true and a query of the pointer-map shows that the page 'nearby' is somewhere on the free-list, then the entire-list will be searched for that page.
#if !SQLITE_OMIT_AUTOVACUUM
if (exact != 0 && nearby <= mxPage)
{
Debug.Assert(nearby > 0);
Debug.Assert(this.AutoVacuum);
PTRMAP eType = 0;
uint dummy0 = 0;
rc = ptrmapGet(nearby, ref eType, ref dummy0);
if (rc != RC.OK)
return rc;
if (eType == PTRMAP.FREEPAGE)
searchList = 1;
pPgno = nearby;
}
#endif
// Decrement the free-list count by 1. Set iTrunk to the index of the first free-list trunk page. iPrevTrunk is initially 1.
rc = Pager.Write(pPage1.DbPage);
if (rc != RC.OK)
return rc;
ConvertEx.Put4(pPage1.Data, 36, n - 1);
// The code within this loop is run only once if the 'searchList' variable is not true. Otherwise, it runs once for each trunk-page on the
// free-list until the page 'nearby' is located.
do
{
pPrevTrunk = pTrunk;
iTrunk = (pPrevTrunk != null ? ConvertEx.Get4(pPrevTrunk.Data, 0) : ConvertEx.Get4(pPage1.Data, 32));
rc = (iTrunk > mxPage ? SysEx.SQLITE_CORRUPT_BKPT() : btreeGetPage(iTrunk, ref pTrunk, 0));
if (rc != RC.OK)
{
pTrunk = null;
goto end_allocate_page;
}
var k = ConvertEx.Get4(pTrunk.Data, 4); // # of leaves on this trunk page
if (k == 0 && searchList == 0)
{
// The trunk has no leaves and the list is not being searched. So extract the trunk page itself and use it as the newly allocated page
Debug.Assert(pPrevTrunk == null);
rc = Pager.Write(pTrunk.DbPage);
if (rc != RC.OK)
goto end_allocate_page;
pPgno = iTrunk;
Buffer.BlockCopy(pTrunk.Data, 0, pPage1.Data, 32, 4);
ppPage = pTrunk;
pTrunk = null;
Btree.TRACE("ALLOCATE: %d trunk - %d free pages left\n", pPgno, n - 1);
}
else if (k > (uint)(this.UsableSize / 4 - 2))
{
// Value of k is out of range. Database corruption
rc = SysEx.SQLITE_CORRUPT_BKPT();
goto end_allocate_page;
#if !SQLITE_OMIT_AUTOVACUUM
}
else if (searchList != 0 && nearby == iTrunk)
{
// The list is being searched and this trunk page is the page to allocate, regardless of whether it has leaves.
Debug.Assert(pPgno == iTrunk);
ppPage = pTrunk;
searchList = 0;
rc = Pager.Write(pTrunk.DbPage);
if (rc != RC.OK)
goto end_allocate_page;
if (k == 0)
{
if (pPrevTrunk == null)
{
pPage1.Data[32 + 0] = pTrunk.Data[0 + 0];
pPage1.Data[32 + 1] = pTrunk.Data[0 + 1];
pPage1.Data[32 + 2] = pTrunk.Data[0 + 2];
pPage1.Data[32 + 3] = pTrunk.Data[0 + 3];
}
else
{
rc = Pager.Write(pPrevTrunk.DbPage);
if (rc != RC.OK)
goto end_allocate_page;
pPrevTrunk.Data[0 + 0] = pTrunk.Data[0 + 0];
pPrevTrunk.Data[0 + 1] = pTrunk.Data[0 + 1];
pPrevTrunk.Data[0 + 2] = pTrunk.Data[0 + 2];
pPrevTrunk.Data[0 + 3] = pTrunk.Data[0 + 3];
}
}
else
{
// The trunk page is required by the caller but it contains pointers to free-list leaves. The first leaf becomes a trunk page in this case.
var pNewTrunk = new MemPage();
var iNewTrunk = (Pgno)ConvertEx.Get4(pTrunk.Data, 8);
if (iNewTrunk > mxPage)
{
rc = SysEx.SQLITE_CORRUPT_BKPT();
goto end_allocate_page;
}
rc = btreeGetPage(iNewTrunk, ref pNewTrunk, 0);
if (rc != RC.OK)
goto end_allocate_page;
rc = Pager.Write(pNewTrunk.DbPage);
if (rc != RC.OK)
{
pNewTrunk.releasePage();
goto end_allocate_page;
}
pNewTrunk.Data[0 + 0] = pTrunk.Data[0 + 0];
pNewTrunk.Data[0 + 1] = pTrunk.Data[0 + 1];
pNewTrunk.Data[0 + 2] = pTrunk.Data[0 + 2];
pNewTrunk.Data[0 + 3] = pTrunk.Data[0 + 3];
ConvertEx.Put4(pNewTrunk.Data, 4, (uint)(k - 1));
Buffer.BlockCopy(pTrunk.Data, 12, pNewTrunk.Data, 8, (int)(k - 1) * 4);
pNewTrunk.releasePage();
if (pPrevTrunk == null)
{
Debug.Assert(Pager.IsPageWriteable(pPage1.DbPage));
ConvertEx.Put4(pPage1.Data, 32, iNewTrunk);
}
else
{
rc = Pager.Write(pPrevTrunk.DbPage);
if (rc != RC.OK)
goto end_allocate_page;
ConvertEx.Put4(pPrevTrunk.Data, 0, iNewTrunk);
}
}
pTrunk = null;
Btree.TRACE("ALLOCATE: %d trunk - %d free pages left\n", pPgno, n - 1);
#endif
}
else if (k > 0)
{
// Extract a leaf from the trunk
uint closest;
var aData = pTrunk.Data;
if (nearby > 0)
{
closest = 0;
var dist = Math.Abs((int)(ConvertEx.Get4(aData, 8) - nearby));
for (uint i = 1; i < k; i++)
{
int dist2 = Math.Abs((int)(ConvertEx.Get4(aData, 8 + i * 4) - nearby));
if (dist2 < dist)
{
closest = i;
dist = dist2;
}
}
}
else
closest = 0;
//
var iPage = (Pgno)ConvertEx.Get4(aData, 8 + closest * 4);
if (iPage > mxPage)
{
rc = SysEx.SQLITE_CORRUPT_BKPT();
goto end_allocate_page;
}
if (searchList == 0 || iPage == nearby)
{
pPgno = iPage;
Btree.TRACE("ALLOCATE: %d was leaf %d of %d on trunk %d" + ": %d more free pages\n", pPgno, closest + 1, k, pTrunk.ID, n - 1);
rc = Pager.Write(pTrunk.DbPage);
if (rc != RC.OK)
goto end_allocate_page;
if (closest < k - 1)
Buffer.BlockCopy(aData, (int)(4 + k * 4), aData, 8 + (int)closest * 4, 4);
ConvertEx.Put4(aData, 4, (k - 1));
var noContent = (!btreeGetHasContent(pPgno) ? 1 : 0);
rc = btreeGetPage(pPgno, ref ppPage, noContent);
if (rc == RC.OK)
{
rc = Pager.Write((ppPage).DbPage);
if (rc != RC.OK)
ppPage.releasePage();
}
searchList = 0;
}
}
pPrevTrunk.releasePage();
pPrevTrunk = null;
} while (searchList != 0);
}
else
{
// There are no pages on the freelist, so create a new page at the end of the file
rc = Pager.Write(this.Page1.DbPage);
if (rc != RC.OK)
return rc;
this.Pages++;
if (this.Pages == MemPage.PENDING_BYTE_PAGE(this))
this.Pages++;
#if !SQLITE_OMIT_AUTOVACUUM
if (this.AutoVacuum && MemPage.PTRMAP_ISPAGE(this, this.Pages))
{
// If pPgno refers to a pointer-map page, allocate two new pages at the end of the file instead of one. The first allocated page
// becomes a new pointer-map page, the second is used by the caller.
MemPage pPg = null;
Btree.TRACE("ALLOCATE: %d from end of file (pointer-map page)\n", pPgno);
Debug.Assert(this.Pages != MemPage.PENDING_BYTE_PAGE(this));
rc = btreeGetPage(this.Pages, ref pPg, 1);
if (rc == RC.OK)
{
rc = Pager.Write(pPg.DbPage);
pPg.releasePage();
}
if (rc != RC.OK)
return rc;
this.Pages++;
if (this.Pages == MemPage.PENDING_BYTE_PAGE(this))
this.Pages++;
}
#endif
ConvertEx.Put4(this.Page1.Data, 28, this.Pages);
pPgno = this.Pages;
Debug.Assert(pPgno != MemPage.PENDING_BYTE_PAGE(this));
rc = btreeGetPage(pPgno, ref ppPage, 1);
if (rc != RC.OK)
return rc;
rc = Pager.Write((ppPage).DbPage);
if (rc != RC.OK)
ppPage.releasePage();
Btree.TRACE("ALLOCATE: %d from end of file\n", pPgno);
}
Debug.Assert(pPgno != MemPage.PENDING_BYTE_PAGE(this));
end_allocate_page:
pTrunk.releasePage();
pPrevTrunk.releasePage();
if (rc == RC.OK)
{
if (Pager.GetPageRefCount((ppPage).DbPage) > 1)
{
ppPage.releasePage();
return SysEx.SQLITE_CORRUPT_BKPT();
}
(ppPage).HasInit = false;
}
else
ppPage = null;
Debug.Assert(rc != RC.OK || Pager.IsPageWriteable((ppPage).DbPage));
return rc;
}
internal RC btreeCreateTable(ref int piTable, CREATETABLE createTabFlags)
{
var pBt = this.Shared;
var pRoot = new MemPage();
Pgno pgnoRoot = 0;
int ptfFlags; // Page-type flage for the root page of new table
RC rc;
Debug.Assert(sqlite3BtreeHoldsMutex());
Debug.Assert(pBt.InTransaction == TRANS.WRITE);
Debug.Assert(!pBt.ReadOnly);
#if SQLITE_OMIT_AUTOVACUUM
rc = allocateBtreePage(pBt, ref pRoot, ref pgnoRoot, 1, 0);
if (rc != SQLITE.OK)
return rc;
#else
if (pBt.AutoVacuum)
{
Pgno pgnoMove = 0; // Move a page here to make room for the root-page
var pPageMove = new MemPage(); // The page to move to.
// Creating a new table may probably require moving an existing database to make room for the new tables root page. In case this page turns
// out to be an overflow page, delete all overflow page-map caches held by open cursors.
invalidateAllOverflowCache(pBt);
// Read the value of meta[3] from the database to determine where the root page of the new table should go. meta[3] is the largest root-page
// created so far, so the new root-page is (meta[3]+1).
GetMeta((int)META.LARGEST_ROOT_PAGE, ref pgnoRoot);
pgnoRoot++;
// The new root-page may not be allocated on a pointer-map page, or the PENDING_BYTE page.
while (pgnoRoot == MemPage.PTRMAP_PAGENO(pBt, pgnoRoot) || pgnoRoot == MemPage.PENDING_BYTE_PAGE(pBt))
pgnoRoot++;
Debug.Assert(pgnoRoot >= 3);
// Allocate a page. The page that currently resides at pgnoRoot will be moved to the allocated page (unless the allocated page happens to reside at pgnoRoot).
rc = pBt.allocateBtreePage(ref pPageMove, ref pgnoMove, pgnoRoot, 1);
if (rc != RC.OK)
return rc;
if (pgnoMove != pgnoRoot)
{
// pgnoRoot is the page that will be used for the root-page of the new table (assuming an error did not occur). But we were
// allocated pgnoMove. If required (i.e. if it was not allocated by extending the file), the current page at position pgnoMove
// is already journaled.
PTRMAP eType = 0;
Pgno iPtrPage = 0;
pPageMove.releasePage();
// Move the page currently at pgnoRoot to pgnoMove.
rc = pBt.btreeGetPage(pgnoRoot, ref pRoot, 0);
if (rc != RC.OK)
return rc;
rc = pBt.ptrmapGet(pgnoRoot, ref eType, ref iPtrPage);
if (eType == PTRMAP.ROOTPAGE || eType == PTRMAP.FREEPAGE)
rc = SysEx.SQLITE_CORRUPT_BKPT();
if (rc != RC.OK)
{
pRoot.releasePage();
return rc;
}
Debug.Assert(eType != PTRMAP.ROOTPAGE);
Debug.Assert(eType != PTRMAP.FREEPAGE);
rc = MemPage.relocatePage(pBt, pRoot, eType, iPtrPage, pgnoMove, 0);
pRoot.releasePage();
// Obtain the page at pgnoRoot
if (rc != RC.OK)
return rc;
rc = pBt.btreeGetPage(pgnoRoot, ref pRoot, 0);
if (rc != RC.OK)
return rc;
rc = Pager.Write(pRoot.DbPage);
if (rc != RC.OK)
{
pRoot.releasePage();
return rc;
}
}
else
pRoot = pPageMove;
// Update the pointer-map and meta-data with the new root-page number.
pBt.ptrmapPut(pgnoRoot, PTRMAP.ROOTPAGE, 0, ref rc);
if (rc != RC.OK)
{
pRoot.releasePage();
return rc;
}
// When the new root page was allocated, page 1 was made writable in order either to increase the database filesize, or to decrement the
// freelist count. Hence, the sqlite3BtreeUpdateMeta() call cannot fail.
Debug.Assert(Pager.IsPageWriteable(pBt.Page1.DbPage));
rc = SetMeta(4, pgnoRoot);
if (Check.NEVER(rc != RC.OK))
{
pRoot.releasePage();
return rc;
}
}
else
{
rc = pBt.allocateBtreePage(ref pRoot, ref pgnoRoot, 1, 0);
if (rc != RC.OK)
return rc;
}
#endif
Debug.Assert(Pager.IsPageWriteable(pRoot.DbPage));
ptfFlags = ((createTabFlags & CREATETABLE.INTKEY) != 0 ? PTF_INTKEY | PTF_LEAFDATA | PTF_LEAF : PTF_ZERODATA | PTF_LEAF);
pRoot.zeroPage(ptfFlags);
Pager.Unref(pRoot.DbPage);
Debug.Assert((pBt.OpenFlags & OPEN.SINGLE) == 0 || pgnoRoot == 2);
piTable = (int)pgnoRoot;
return RC.OK;
}
internal static void assertParentIndex(MemPage pParent, int iIdx, Pgno iChild)
{
}
internal RC btreeCreateTable(ref int piTable, CREATETABLE createTabFlags)
{
var pBt = this.Shared;
var pRoot = new MemPage();
Pgno pgnoRoot = 0;
int ptfFlags; // Page-type flage for the root page of new table
RC rc;
Debug.Assert(sqlite3BtreeHoldsMutex());
Debug.Assert(pBt.InTransaction == TRANS.WRITE);
Debug.Assert(!pBt.ReadOnly);
#if SQLITE_OMIT_AUTOVACUUM
rc = allocateBtreePage(pBt, ref pRoot, ref pgnoRoot, 1, 0);
if (rc != SQLITE.OK)
{
return(rc);
}
#else
if (pBt.AutoVacuum)
{
Pgno pgnoMove = 0; // Move a page here to make room for the root-page
var pPageMove = new MemPage(); // The page to move to.
// Creating a new table may probably require moving an existing database to make room for the new tables root page. In case this page turns
// out to be an overflow page, delete all overflow page-map caches held by open cursors.
invalidateAllOverflowCache(pBt);
// Read the value of meta[3] from the database to determine where the root page of the new table should go. meta[3] is the largest root-page
// created so far, so the new root-page is (meta[3]+1).
GetMeta((int)META.LARGEST_ROOT_PAGE, ref pgnoRoot);
pgnoRoot++;
// The new root-page may not be allocated on a pointer-map page, or the PENDING_BYTE page.
while (pgnoRoot == MemPage.PTRMAP_PAGENO(pBt, pgnoRoot) || pgnoRoot == MemPage.PENDING_BYTE_PAGE(pBt))
{
pgnoRoot++;
}
Debug.Assert(pgnoRoot >= 3);
// Allocate a page. The page that currently resides at pgnoRoot will be moved to the allocated page (unless the allocated page happens to reside at pgnoRoot).
rc = pBt.allocateBtreePage(ref pPageMove, ref pgnoMove, pgnoRoot, 1);
if (rc != RC.OK)
{
return(rc);
}
if (pgnoMove != pgnoRoot)
{
// pgnoRoot is the page that will be used for the root-page of the new table (assuming an error did not occur). But we were
// allocated pgnoMove. If required (i.e. if it was not allocated by extending the file), the current page at position pgnoMove
// is already journaled.
PTRMAP eType = 0;
Pgno iPtrPage = 0;
pPageMove.releasePage();
// Move the page currently at pgnoRoot to pgnoMove.
rc = pBt.btreeGetPage(pgnoRoot, ref pRoot, 0);
if (rc != RC.OK)
{
return(rc);
}
rc = pBt.ptrmapGet(pgnoRoot, ref eType, ref iPtrPage);
if (eType == PTRMAP.ROOTPAGE || eType == PTRMAP.FREEPAGE)
{
rc = SysEx.SQLITE_CORRUPT_BKPT();
}
if (rc != RC.OK)
{
pRoot.releasePage();
return(rc);
}
Debug.Assert(eType != PTRMAP.ROOTPAGE);
Debug.Assert(eType != PTRMAP.FREEPAGE);
rc = MemPage.relocatePage(pBt, pRoot, eType, iPtrPage, pgnoMove, 0);
pRoot.releasePage();
// Obtain the page at pgnoRoot
if (rc != RC.OK)
{
return(rc);
}
rc = pBt.btreeGetPage(pgnoRoot, ref pRoot, 0);
if (rc != RC.OK)
{
return(rc);
}
rc = Pager.Write(pRoot.DbPage);
if (rc != RC.OK)
{
pRoot.releasePage();
return(rc);
}
}
else
{
pRoot = pPageMove;
}
// Update the pointer-map and meta-data with the new root-page number.
pBt.ptrmapPut(pgnoRoot, PTRMAP.ROOTPAGE, 0, ref rc);
if (rc != RC.OK)
{
pRoot.releasePage();
return(rc);
}
// When the new root page was allocated, page 1 was made writable in order either to increase the database filesize, or to decrement the
// freelist count. Hence, the sqlite3BtreeUpdateMeta() call cannot fail.
Debug.Assert(Pager.IsPageWriteable(pBt.Page1.DbPage));
rc = SetMeta(4, pgnoRoot);
if (Check.NEVER(rc != RC.OK))
{
pRoot.releasePage();
return(rc);
}
}
else
{
rc = pBt.allocateBtreePage(ref pRoot, ref pgnoRoot, 1, 0);
if (rc != RC.OK)
{
return(rc);
}
}
#endif
Debug.Assert(Pager.IsPageWriteable(pRoot.DbPage));
ptfFlags = ((createTabFlags & CREATETABLE.INTKEY) != 0 ? PTF_INTKEY | PTF_LEAFDATA | PTF_LEAF : PTF_ZERODATA | PTF_LEAF);
pRoot.zeroPage(ptfFlags);
Pager.Unref(pRoot.DbPage);
Debug.Assert((pBt.OpenFlags & OPEN.SINGLE) == 0 || pgnoRoot == 2);
piTable = (int)pgnoRoot;
return(RC.OK);
}
internal RC btreeDropTable(Pgno iTable, ref int piMoved)
{
MemPage pPage = null;
var pBt = this.Shared;
Debug.Assert(sqlite3BtreeHoldsMutex());
Debug.Assert(this.InTransaction == TRANS.WRITE);
// It is illegal to drop a table if any cursors are open on the database. This is because in auto-vacuum mode the backend may
// need to move another root-page to fill a gap left by the deleted root page. If an open cursor was using this page a problem would occur.
// This error is caught long before control reaches this point.
if (Check.NEVER(pBt.Cursors) != null)
{
sqlite3b.sqlite3ConnectionBlocked(this.DB, pBt.Cursors.Tree.DB);
return RC.LOCKED_SHAREDCACHE;
}
var rc = pBt.btreeGetPage((Pgno)iTable, ref pPage, 0);
if (rc != RC.OK)
return rc;
var dummy0 = 0;
rc = ClearTable((int)iTable, ref dummy0);
if (rc != RC.OK)
{
pPage.releasePage();
return rc;
}
piMoved = 0;
if (iTable > 1)
{
#if SQLITE_OMIT_AUTOVACUUM
freePage(pPage, ref rc);
releasePage(pPage);
#else
if (pBt.AutoVacuum)
{
Pgno maxRootPgno = 0;
GetMeta((int)META.LARGEST_ROOT_PAGE, ref maxRootPgno);
if (iTable == maxRootPgno)
{
// If the table being dropped is the table with the largest root-page number in the database, put the root page on the free list.
pPage.freePage(ref rc);
pPage.releasePage();
if (rc != RC.OK)
return rc;
}
else
{
// The table being dropped does not have the largest root-page number in the database. So move the page that does into the
// gap left by the deleted root-page.
var pMove = new MemPage();
pPage.releasePage();
rc = pBt.btreeGetPage(maxRootPgno, ref pMove, 0);
if (rc != RC.OK)
return rc;
rc = MemPage.relocatePage(pBt, pMove, PTRMAP.ROOTPAGE, 0, iTable, 0);
pMove.releasePage();
if (rc != RC.OK)
return rc;
pMove = null;
rc = pBt.btreeGetPage(maxRootPgno, ref pMove, 0);
pMove.freePage(ref rc);
pMove.releasePage();
if (rc != RC.OK)
return rc;
piMoved = (int)maxRootPgno;
}
// Set the new 'max-root-page' value in the database header. This is the old value less one, less one more if that happens to
// be a root-page number, less one again if that is the PENDING_BYTE_PAGE.
maxRootPgno--;
while (maxRootPgno == MemPage.PENDING_BYTE_PAGE(pBt) || MemPage.PTRMAP_ISPAGE(pBt, maxRootPgno))
maxRootPgno--;
Debug.Assert(maxRootPgno != MemPage.PENDING_BYTE_PAGE(pBt));
rc = SetMeta(4, maxRootPgno);
}
else
{
pPage.freePage(ref rc);
pPage.releasePage();
}
#endif
}
else
{
// If sqlite3BtreeDropTable was called on page 1. This really never should happen except in a corrupt database.
pPage.zeroPage(PTF_INTKEY | PTF_LEAF);
pPage.releasePage();
}
return rc;
}
internal RC btreeDropTable(Pgno iTable, ref int piMoved)
{
MemPage pPage = null;
var pBt = this.Shared;
Debug.Assert(sqlite3BtreeHoldsMutex());
Debug.Assert(this.InTransaction == TRANS.WRITE);
// It is illegal to drop a table if any cursors are open on the database. This is because in auto-vacuum mode the backend may
// need to move another root-page to fill a gap left by the deleted root page. If an open cursor was using this page a problem would occur.
// This error is caught long before control reaches this point.
if (Check.NEVER(pBt.Cursors) != null)
{
sqlite3b.sqlite3ConnectionBlocked(this.DB, pBt.Cursors.Tree.DB);
return(RC.LOCKED_SHAREDCACHE);
}
var rc = pBt.btreeGetPage((Pgno)iTable, ref pPage, 0);
if (rc != RC.OK)
{
return(rc);
}
var dummy0 = 0;
rc = ClearTable((int)iTable, ref dummy0);
if (rc != RC.OK)
{
pPage.releasePage();
return(rc);
}
piMoved = 0;
if (iTable > 1)
{
#if SQLITE_OMIT_AUTOVACUUM
freePage(pPage, ref rc);
releasePage(pPage);
#else
if (pBt.AutoVacuum)
{
Pgno maxRootPgno = 0;
GetMeta((int)META.LARGEST_ROOT_PAGE, ref maxRootPgno);
if (iTable == maxRootPgno)
{
// If the table being dropped is the table with the largest root-page number in the database, put the root page on the free list.
pPage.freePage(ref rc);
pPage.releasePage();
if (rc != RC.OK)
{
return(rc);
}
}
else
{
// The table being dropped does not have the largest root-page number in the database. So move the page that does into the
// gap left by the deleted root-page.
var pMove = new MemPage();
pPage.releasePage();
rc = pBt.btreeGetPage(maxRootPgno, ref pMove, 0);
if (rc != RC.OK)
{
return(rc);
}
rc = MemPage.relocatePage(pBt, pMove, PTRMAP.ROOTPAGE, 0, iTable, 0);
pMove.releasePage();
if (rc != RC.OK)
{
return(rc);
}
pMove = null;
rc = pBt.btreeGetPage(maxRootPgno, ref pMove, 0);
pMove.freePage(ref rc);
pMove.releasePage();
if (rc != RC.OK)
{
return(rc);
}
piMoved = (int)maxRootPgno;
}
// Set the new 'max-root-page' value in the database header. This is the old value less one, less one more if that happens to
// be a root-page number, less one again if that is the PENDING_BYTE_PAGE.
maxRootPgno--;
while (maxRootPgno == MemPage.PENDING_BYTE_PAGE(pBt) || MemPage.PTRMAP_ISPAGE(pBt, maxRootPgno))
{
maxRootPgno--;
}
Debug.Assert(maxRootPgno != MemPage.PENDING_BYTE_PAGE(pBt));
rc = SetMeta(4, maxRootPgno);
}
else
{
pPage.freePage(ref rc);
pPage.releasePage();
}
#endif
}
else
{
// If sqlite3BtreeDropTable was called on page 1. This really never should happen except in a corrupt database.
pPage.zeroPage(PTF_INTKEY | PTF_LEAF);
pPage.releasePage();
}
return(rc);
}
internal RC getAndInitPage(Pgno pgno, ref MemPage ppPage)
{
Debug.Assert(MutexEx.Held(this.Mutex));
RC rc;
if (pgno > btreePagecount())
rc = SysEx.SQLITE_CORRUPT_BKPT();
else
{
rc = btreeGetPage(pgno, ref ppPage, 0);
if (rc == RC.OK)
{
rc = ppPage.btreeInitPage();
if (rc != RC.OK)
ppPage.releasePage();
}
}
Debug.Assert(pgno != 0 || rc == RC.CORRUPT);
return rc;
}
internal static RC incrVacuumStep(BtShared pBt, Pgno nFin, Pgno iLastPg)
{
Pgno nFreeList; // Number of pages still on the free-list
Debug.Assert(MutexEx.Held(pBt.Mutex));
Debug.Assert(iLastPg > nFin);
if (!PTRMAP_ISPAGE(pBt, iLastPg) && iLastPg != PENDING_BYTE_PAGE(pBt))
{
PTRMAP eType = 0;
Pgno iPtrPage = 0;
nFreeList = ConvertEx.Get4(pBt.Page1.Data, 36);
if (nFreeList == 0)
{
return(RC.DONE);
}
var rc = pBt.ptrmapGet(iLastPg, ref eType, ref iPtrPage);
if (rc != RC.OK)
{
return(rc);
}
if (eType == PTRMAP.ROOTPAGE)
{
return(SysEx.SQLITE_CORRUPT_BKPT());
}
if (eType == PTRMAP.FREEPAGE)
{
if (nFin == 0)
{
// Remove the page from the files free-list. This is not required if nFin is non-zero. In that case, the free-list will be
// truncated to zero after this function returns, so it doesn't matter if it still contains some garbage entries.
Pgno iFreePg = 0;
var pFreePg = new MemPage();
rc = pBt.allocateBtreePage(ref pFreePg, ref iFreePg, iLastPg, 1);
if (rc != RC.OK)
{
return(rc);
}
Debug.Assert(iFreePg == iLastPg);
pFreePg.releasePage();
}
}
else
{
Pgno iFreePg = 0; // Index of free page to move pLastPg to
var pLastPg = new MemPage();
rc = pBt.btreeGetPage(iLastPg, ref pLastPg, 0);
if (rc != RC.OK)
{
return(rc);
}
// If nFin is zero, this loop runs exactly once and page pLastPg is swapped with the first free page pulled off the free list.
// On the other hand, if nFin is greater than zero, then keep looping until a free-page located within the first nFin pages of the file is found.
do
{
var pFreePg = new MemPage();
rc = pBt.allocateBtreePage(ref pFreePg, ref iFreePg, 0, 0);
if (rc != RC.OK)
{
pLastPg.releasePage();
return(rc);
}
pFreePg.releasePage();
} while (nFin != 0 && iFreePg > nFin);
Debug.Assert(iFreePg < iLastPg);
rc = Pager.Write(pLastPg.DbPage);
if (rc == RC.OK)
{
rc = relocatePage(pBt, pLastPg, eType, iPtrPage, iFreePg, (nFin != 0) ? 1 : 0);
}
pLastPg.releasePage();
if (rc != RC.OK)
{
return(rc);
}
}
}
if (nFin == 0)
{
iLastPg--;
while (iLastPg == PENDING_BYTE_PAGE(pBt) || PTRMAP_ISPAGE(pBt, iLastPg))
{
if (PTRMAP_ISPAGE(pBt, iLastPg))
{
var pPg = new MemPage();
var rc = pBt.btreeGetPage(iLastPg, ref pPg, 0);
if (rc != RC.OK)
{
return(rc);
}
rc = Pager.Write(pPg.DbPage);
pPg.releasePage();
if (rc != RC.OK)
{
return(rc);
}
}
iLastPg--;
}
pBt.Pager.TruncateImage(iLastPg);
pBt.Pages = iLastPg;
}
return(RC.OK);
}
internal RC fillInCell(byte[] pCell, byte[] pKey, long nKey, byte[] pData, int nData, int nZero, ref int pnSize)
{
Debug.Assert(MutexEx.Held(this.Shared.Mutex));
// pPage is not necessarily writeable since pCell might be auxiliary buffer space that is separate from the pPage buffer area
// TODO -- Determine if the following Assert is needed under c#
//Debug.Assert( pCell < pPage.aData || pCell >= &pPage.aData[pBt.pageSize] || sqlite3PagerIswriteable(pPage.pDbPage) );
// Fill in the header.
var nHeader = 0;
if (this.Leaf == 0)
{
nHeader += 4;
}
if (this.HasData != 0)
{
nHeader += (int)ConvertEx.PutVariant9(pCell, (uint)nHeader, (int)(nData + nZero));
}
else
{
nData = nZero = 0;
}
nHeader += ConvertEx.PutVariant9L(pCell, (uint)nHeader, (ulong)nKey);
var info = new CellInfo();
btreeParseCellPtr(pCell, ref info);
Debug.Assert(info.nHeader == nHeader);
Debug.Assert(info.nKey == nKey);
Debug.Assert(info.nData == (uint)(nData + nZero));
// Fill in the payload
var nPayload = nData + nZero;
byte[] pSrc;
int nSrc;
if (this.HasIntKey)
{
pSrc = pData;
nSrc = nData;
nData = 0;
}
else
{
if (Check.NEVER(nKey > 0x7fffffff || pKey == null))
{
return(SysEx.SQLITE_CORRUPT_BKPT());
}
nPayload += (int)nKey;
pSrc = pKey;
nSrc = (int)nKey;
}
pnSize = info.nSize;
var spaceLeft = (int)info.nLocal;
var pPayload = pCell;
var pPayloadIndex = nHeader;
var pPrior = pCell;
var pPriorIndex = (int)info.iOverflow;
var pBt = this.Shared;
Pgno pgnoOvfl = 0;
MemPage pToRelease = null;
while (nPayload > 0)
{
if (spaceLeft == 0)
{
#if !SQLITE_OMIT_AUTOVACUUM
var pgnoPtrmap = pgnoOvfl; // Overflow page pointer-map entry page
if (pBt.AutoVacuum)
{
do
{
pgnoOvfl++;
}while (PTRMAP_ISPAGE(pBt, pgnoOvfl) || pgnoOvfl == PENDING_BYTE_PAGE(pBt));
}
#endif
MemPage pOvfl = null;
var rc = pBt.allocateBtreePage(ref pOvfl, ref pgnoOvfl, pgnoOvfl, 0);
#if !SQLITE_OMIT_AUTOVACUUM
// If the database supports auto-vacuum, and the second or subsequent overflow page is being allocated, add an entry to the pointer-map for that page now.
// If this is the first overflow page, then write a partial entry to the pointer-map. If we write nothing to this pointer-map slot,
// then the optimistic overflow chain processing in clearCell() may misinterpret the uninitialised values and delete the
// wrong pages from the database.
if (pBt.AutoVacuum && rc == RC.OK)
{
var eType = (pgnoPtrmap != 0 ? PTRMAP.OVERFLOW2 : PTRMAP.OVERFLOW1);
pBt.ptrmapPut(pgnoOvfl, eType, pgnoPtrmap, ref rc);
if (rc != RC.OK)
{
pOvfl.releasePage();
}
}
#endif
if (rc != RC.OK)
{
pToRelease.releasePage();
return(rc);
}
// If pToRelease is not zero than pPrior points into the data area of pToRelease. Make sure pToRelease is still writeable.
Debug.Assert(pToRelease == null || Pager.IsPageWriteable(pToRelease.DbPage));
// If pPrior is part of the data area of pPage, then make sure pPage is still writeable
// TODO -- Determine if the following Assert is needed under c#
//Debug.Assert( pPrior < pPage.aData || pPrior >= &pPage.aData[pBt.pageSize] || sqlite3PagerIswriteable(pPage.pDbPage) );
ConvertEx.Put4L(pPrior, (uint)pPriorIndex, pgnoOvfl);
pToRelease.releasePage();
pToRelease = pOvfl;
pPrior = pOvfl.Data;
pPriorIndex = 0;
ConvertEx.Put4(pPrior, 0);
pPayload = pOvfl.Data;
pPayloadIndex = 4;
spaceLeft = (int)pBt.UsableSize - 4;
}
var n = nPayload;
if (n > spaceLeft)
{
n = spaceLeft;
}
// If pToRelease is not zero than pPayload points into the data area of pToRelease. Make sure pToRelease is still writeable.
Debug.Assert(pToRelease == null || Pager.IsPageWriteable(pToRelease.DbPage));
// If pPayload is part of the data area of pPage, then make sure pPage is still writeable
// TODO -- Determine if the following Assert is needed under c#
//Debug.Assert( pPayload < pPage.aData || pPayload >= &pPage.aData[pBt.pageSize] || sqlite3PagerIswriteable(pPage.pDbPage) );
var pSrcIndex = 0;
if (nSrc > 0)
{
if (n > nSrc)
{
n = nSrc;
}
Debug.Assert(pSrc != null);
Buffer.BlockCopy(pSrc, pSrcIndex, pPayload, pPayloadIndex, n);
}
else
{
var pZeroBlob = MallocEx.sqlite3Malloc(n);
Buffer.BlockCopy(pZeroBlob, 0, pPayload, pPayloadIndex, n);
}
nPayload -= n;
pPayloadIndex += n;
pSrcIndex += n;
nSrc -= n;
spaceLeft -= n;
if (nSrc == 0)
{
nSrc = nData;
pSrc = pData;
}
}
pToRelease.releasePage();
return(RC.OK);
}
internal static void assertParentIndex(MemPage pParent, int iIdx, Pgno iChild)
{
}
static int NB = (NN * 2 + 1); // Total pages involved in the balance
#if !SQLITE_OMIT_QUICKBALANCE
internal static RC balance_quick(MemPage parentPage, MemPage page, byte[] space)
{
Debug.Assert(MutexEx.Held(page.Shared.Mutex));
Debug.Assert(Pager.IsPageWriteable(parentPage.DbPage));
Debug.Assert(page.NOverflows == 1);
// This error condition is now caught prior to reaching this function
if (page.Cells <= 0)
{
return(SysEx.SQLITE_CORRUPT_BKPT());
}
// Allocate a new page. This page will become the right-sibling of pPage. Make the parent page writable, so that the new divider cell
// may be inserted. If both these operations are successful, proceed.
var shared = page.Shared; // B-Tree Database
var newPage = new MemPage(); // Newly allocated page
Pgno pgnoNew = 0; // Page number of pNew
var rc = shared.allocateBtreePage(ref newPage, ref pgnoNew, 0, 0);
if (rc != RC.OK)
{
return(rc);
}
var pOut = 4;
var pCell = page.Overflows[0].Cell;
var szCell = new int[1] {
page.cellSizePtr(pCell)
};
Debug.Assert(Pager.IsPageWriteable(newPage.DbPage));
Debug.Assert(page.Data[0] == (Btree.PTF_INTKEY | Btree.PTF_LEAFDATA | Btree.PTF_LEAF));
newPage.zeroPage(Btree.PTF_INTKEY | Btree.PTF_LEAFDATA | Btree.PTF_LEAF);
newPage.assemblePage(1, pCell, szCell);
// If this is an auto-vacuum database, update the pointer map with entries for the new page, and any pointer from the
// cell on the page to an overflow page. If either of these operations fails, the return code is set, but the contents
// of the parent page are still manipulated by thh code below. That is Ok, at this point the parent page is guaranteed to
// be marked as dirty. Returning an error code will cause a rollback, undoing any changes made to the parent page.
#if !SQLITE_OMIT_AUTOVACUUM
if (shared.AutoVacuum)
#else
if (false)
#endif
{
shared.ptrmapPut(pgnoNew, PTRMAP.BTREE, parentPage.ID, ref rc);
if (szCell[0] > newPage.MinLocal)
{
newPage.ptrmapPutOvflPtr(pCell, ref rc);
}
}
// Create a divider cell to insert into pParent. The divider cell consists of a 4-byte page number (the page number of pPage) and
// a variable length key value (which must be the same value as the largest key on pPage).
// To find the largest key value on pPage, first find the right-most cell on pPage. The first two fields of this cell are the
// record-length (a variable length integer at most 32-bits in size) and the key value (a variable length integer, may have any value).
// The first of the while(...) loops below skips over the record-length field. The second while(...) loop copies the key value from the
// cell on pPage into the pSpace buffer.
var iCell = page.FindCell(page.Cells - 1);
pCell = page.Data;
var _pCell = iCell;
var pStop = _pCell + 9;
while (((pCell[_pCell++]) & 0x80) != 0 && _pCell < pStop)
{
;
}
pStop = _pCell + 9;
while (((space[pOut++] = pCell[_pCell++]) & 0x80) != 0 && _pCell < pStop)
{
;
}
// Insert the new divider cell into pParent.
parentPage.insertCell(parentPage.Cells, space, pOut, null, page.ID, ref rc);
// Set the right-child pointer of pParent to point to the new page.
ConvertEx.Put4L(parentPage.Data, parentPage.HeaderOffset + 8, pgnoNew);
// Release the reference to the new page.
newPage.releasePage();
return(rc);
}
internal RC freePage2(MemPage pMemPage, Pgno iPage)
{
MemPage pTrunk = null; // Free-list trunk page
var pPage1 = this.Page1; // Local reference to page 1
Debug.Assert(MutexEx.Held(this.Mutex));
Debug.Assert(iPage > 1);
Debug.Assert(pMemPage == null || pMemPage.ID == iPage);
MemPage pPage; // Page being freed. May be NULL.
if (pMemPage != null)
{
pPage = pMemPage;
Pager.AddPageRef(pPage.DbPage);
}
else
{
pPage = btreePageLookup(iPage);
}
// Increment the free page count on pPage1
var rc = Pager.Write(pPage1.DbPage);
if (rc != RC.OK)
{
goto freepage_out;
}
var nFree = (int)ConvertEx.Get4(pPage1.Data, 36); // Initial number of pages on free-list
ConvertEx.Put4(pPage1.Data, 36, nFree + 1);
if (this.SecureDelete)
{
// If the secure_delete option is enabled, then always fully overwrite deleted information with zeros.
if ((pPage == null && ((rc = btreeGetPage(iPage, ref pPage, 0)) != RC.OK)) || ((rc = Pager.Write(pPage.DbPage)) != RC.OK))
{
goto freepage_out;
}
Array.Clear(pPage.Data, 0, (int)pPage.Shared.PageSize);
}
// If the database supports auto-vacuum, write an entry in the pointer-map to indicate that the page is free.
#if !SQLITE_OMIT_AUTOVACUUM
if (this.AutoVacuum)
#else
if (false)
#endif
{
ptrmapPut(iPage, PTRMAP.FREEPAGE, 0, ref rc);
if (rc != RC.OK)
{
goto freepage_out;
}
}
// Now manipulate the actual database free-list structure. There are two possibilities. If the free-list is currently empty, or if the first
// trunk page in the free-list is full, then this page will become a new free-list trunk page. Otherwise, it will become a leaf of the
// first trunk page in the current free-list. This block tests if it is possible to add the page as a new free-list leaf.
Pgno iTrunk = 0; // Page number of free-list trunk page
if (nFree != 0)
{
uint nLeaf; // Initial number of leaf cells on trunk page
iTrunk = (Pgno)ConvertEx.Get4(pPage1.Data, 32); // Page number of free-list trunk page
rc = btreeGetPage(iTrunk, ref pTrunk, 0);
if (rc != RC.OK)
{
goto freepage_out;
}
nLeaf = ConvertEx.Get4(pTrunk.Data, 4);
Debug.Assert(this.UsableSize > 32);
if (nLeaf > (uint)this.UsableSize / 4 - 2)
{
rc = SysEx.SQLITE_CORRUPT_BKPT();
goto freepage_out;
}
if (nLeaf < (uint)this.UsableSize / 4 - 8)
{
// In this case there is room on the trunk page to insert the page being freed as a new leaf.
// Note: that the trunk page is not really full until it contains usableSize/4 - 2 entries, not usableSize/4 - 8 entries as we have
// coded. But due to a coding error in versions of SQLite prior to 3.6.0, databases with freelist trunk pages holding more than
// usableSize/4 - 8 entries will be reported as corrupt. In order to maintain backwards compatibility with older versions of SQLite,
// we will continue to restrict the number of entries to usableSize/4 - 8 for now. At some point in the future (once everyone has upgraded
// to 3.6.0 or later) we should consider fixing the conditional above to read "usableSize/4-2" instead of "usableSize/4-8".
rc = Pager.Write(pTrunk.DbPage);
if (rc == RC.OK)
{
ConvertEx.Put4(pTrunk.Data, 4, nLeaf + 1);
ConvertEx.Put4(pTrunk.Data, (uint)(8 + nLeaf * 4), iPage);
if (pPage != null && !this.SecureDelete)
{
Pager.DontWrite(pPage.DbPage);
}
rc = btreeSetHasContent(iPage);
}
Btree.TRACE("FREE-PAGE: %d leaf on trunk page %d\n", iPage, pTrunk.ID);
goto freepage_out;
}
}
// If control flows to this point, then it was not possible to add the the page being freed as a leaf page of the first trunk in the free-list.
// Possibly because the free-list is empty, or possibly because the first trunk in the free-list is full. Either way, the page being freed
// will become the new first trunk page in the free-list.
if (pPage == null && (rc = btreeGetPage(iPage, ref pPage, 0)) != RC.OK)
{
goto freepage_out;
}
rc = Pager.Write(pPage.DbPage);
if (rc != RC.OK)
{
goto freepage_out;
}
ConvertEx.Put4L(pPage.Data, iTrunk);
ConvertEx.Put4(pPage.Data, 4, 0);
ConvertEx.Put4(pPage1.Data, 32, iPage);
Btree.TRACE("FREE-PAGE: %d new trunk page replacing %d\n", pPage.ID, iTrunk);
freepage_out:
if (pPage != null)
{
pPage.HasInit = false;
}
pPage.releasePage();
pTrunk.releasePage();
return(rc);
}
static i64 refNULL = 0; //Dummy for C# ref NULL
static int checkTreePage(
IntegrityCk pCheck, /* Context for the sanity check */
int iPage, /* Page number of the page to check */
string zParentContext, /* Parent context */
ref i64 pnParentMinKey,
ref i64 pnParentMaxKey,
object _pnParentMinKey, /* C# Needed to determine if content passed*/
object _pnParentMaxKey /* C# Needed to determine if content passed*/
)
{
MemPage pPage = new MemPage();
int i, rc, depth, d2, pgno, cnt;
int hdr, cellStart;
int nCell;
u8[] data;
BtShared pBt;
int usableSize;
StringBuilder zContext = new StringBuilder(100);
byte[] hit = null;
i64 nMinKey = 0;
i64 nMaxKey = 0;
sqlite3_snprintf(200, zContext, "Page %d: ", iPage);
/* Check that the page exists
*/
pBt = pCheck.pBt;
usableSize = (int)pBt.usableSize;
if (iPage == 0)
{
return(0);
}
if (checkRef(pCheck, (u32)iPage, zParentContext) != 0)
{
return(0);
}
if ((rc = btreeGetPage(pBt, (Pgno)iPage, ref pPage, 0)) != 0)
{
checkAppendMsg(pCheck, zContext.ToString(),
"unable to get the page. error code=%d", rc);
return(0);
}
/* Clear MemPage.isInit to make sure the corruption detection code in
** btreeInitPage() is executed. */
pPage.isInit = 0;
if ((rc = btreeInitPage(pPage)) != 0)
{
Debug.Assert(rc == SQLITE_CORRUPT); /* The only possible error from InitPage */
checkAppendMsg(pCheck, zContext.ToString(),
"btreeInitPage() returns error code %d", rc);
releasePage(pPage);
return(0);
}
/* Check out all the cells.
*/
depth = 0;
for (i = 0; i < pPage.nCell && pCheck.mxErr != 0; i++)
{
u8[] pCell;
u32 sz;
CellInfo info = new CellInfo();
/* Check payload overflow pages
*/
sqlite3_snprintf(200, zContext,
"On tree page %d cell %d: ", iPage, i);
int iCell = findCell(pPage, i); //pCell = findCell( pPage, i );
pCell = pPage.aData;
btreeParseCellPtr(pPage, iCell, ref info); //btreeParseCellPtr( pPage, pCell, info );
sz = info.nData;
if (0 == pPage.intKey)
{
sz += (u32)info.nKey;
}
/* For intKey pages, check that the keys are in order.
*/
else if (i == 0)
{
nMinKey = nMaxKey = info.nKey;
}
else
{
if (info.nKey <= nMaxKey)
{
checkAppendMsg(pCheck, zContext.ToString(),
"Rowid %lld out of order (previous was %lld)", info.nKey, nMaxKey);
}
nMaxKey = info.nKey;
}
Debug.Assert(sz == info.nPayload);
if ((sz > info.nLocal)
//&& (pCell[info.iOverflow]<=&pPage.aData[pBt.usableSize])
)
{
int nPage = (int)(sz - info.nLocal + usableSize - 5) / (usableSize - 4);
Pgno pgnoOvfl = sqlite3Get4byte(pCell, iCell, info.iOverflow);
#if !SQLITE_OMIT_AUTOVACUUM
if (pBt.autoVacuum)
{
checkPtrmap(pCheck, pgnoOvfl, PTRMAP_OVERFLOW1, (u32)iPage, zContext.ToString());
}
#endif
checkList(pCheck, 0, (int)pgnoOvfl, nPage, zContext.ToString());
}
/* Check sanity of left child page.
*/
if (0 == pPage.leaf)
{
pgno = (int)sqlite3Get4byte(pCell, iCell); //sqlite3Get4byte( pCell );
#if !SQLITE_OMIT_AUTOVACUUM
if (pBt.autoVacuum)
{
checkPtrmap(pCheck, (u32)pgno, PTRMAP_BTREE, (u32)iPage, zContext.ToString());
}
#endif
if (i == 0)
{
d2 = checkTreePage(pCheck, pgno, zContext.ToString(), ref nMinKey, ref refNULL, pCheck, null);
}
else
{
d2 = checkTreePage(pCheck, pgno, zContext.ToString(), ref nMinKey, ref nMaxKey, pCheck, pCheck);
}
if (i > 0 && d2 != depth)
{
checkAppendMsg(pCheck, zContext, "Child page depth differs");
}
depth = d2;
}
}
if (0 == pPage.leaf)
{
pgno = (int)sqlite3Get4byte(pPage.aData, pPage.hdrOffset + 8);
sqlite3_snprintf(200, zContext,
"On page %d at right child: ", iPage);
#if !SQLITE_OMIT_AUTOVACUUM
if (pBt.autoVacuum)
{
checkPtrmap(pCheck, (u32)pgno, PTRMAP_BTREE, (u32)iPage, zContext.ToString());
}
#endif
// checkTreePage(pCheck, pgno, zContext, NULL, !pPage->nCell ? NULL : &nMaxKey);
if (0 == pPage.nCell)
{
checkTreePage(pCheck, pgno, zContext.ToString(), ref refNULL, ref refNULL, null, null);
}
else
{
checkTreePage(pCheck, pgno, zContext.ToString(), ref refNULL, ref nMaxKey, null, pCheck);
}
}
/* For intKey leaf pages, check that the min/max keys are in order
** with any left/parent/right pages.
*/
if (pPage.leaf != 0 && pPage.intKey != 0)
{
/* if we are a left child page */
if (_pnParentMinKey != null)
{
/* if we are the left most child page */
if (_pnParentMaxKey == null)
{
if (nMaxKey > pnParentMinKey)
{
checkAppendMsg(pCheck, zContext,
"Rowid %lld out of order (max larger than parent min of %lld)",
nMaxKey, pnParentMinKey);
}
}
else
{
if (nMinKey <= pnParentMinKey)
{
checkAppendMsg(pCheck, zContext,
"Rowid %lld out of order (min less than parent min of %lld)",
nMinKey, pnParentMinKey);
}
if (nMaxKey > pnParentMaxKey)
{
checkAppendMsg(pCheck, zContext,
"Rowid %lld out of order (max larger than parent max of %lld)",
nMaxKey, pnParentMaxKey);
}
pnParentMinKey = nMaxKey;
}
/* else if we're a right child page */
}
else if (_pnParentMaxKey != null)
{
if (nMinKey <= pnParentMaxKey)
{
checkAppendMsg(pCheck, zContext,
"Rowid %lld out of order (min less than parent max of %lld)",
nMinKey, pnParentMaxKey);
}
}
}
/* Check for complete coverage of the page
*/
data = pPage.aData;
hdr = pPage.hdrOffset;
hit = sqlite3Malloc(pBt.pageSize);
//if( hit==null ){
// pCheck.mallocFailed = 1;
//}else
{
int contentOffset = get2byteNotZero(data, hdr + 5);
Debug.Assert(contentOffset <= usableSize); /* Enforced by btreeInitPage() */
Array.Clear(hit, contentOffset, usableSize - contentOffset); //memset(hit+contentOffset, 0, usableSize-contentOffset);
for (int iLoop = contentOffset - 1; iLoop >= 0; iLoop--)
{
hit[iLoop] = 1;//memset(hit, 1, contentOffset);
}
nCell = get2byte(data, hdr + 3);
cellStart = hdr + 12 - 4 * pPage.leaf;
for (i = 0; i < nCell; i++)
{
int pc = get2byte(data, cellStart + i * 2);
u32 size = 65536;
int j;
if (pc <= usableSize - 4)
{
size = cellSizePtr(pPage, data, pc);
}
if ((int)(pc + size - 1) >= usableSize)
{
checkAppendMsg(pCheck, "",
"Corruption detected in cell %d on page %d", i, iPage);
}
else
{
for (j = (int)(pc + size - 1); j >= pc; j--)
{
hit[j]++;
}
}
}
i = get2byte(data, hdr + 1);
while (i > 0)
{
int size, j;
Debug.Assert(i <= usableSize - 4); /* Enforced by btreeInitPage() */
size = get2byte(data, i + 2);
Debug.Assert(i + size <= usableSize); /* Enforced by btreeInitPage() */
for (j = i + size - 1; j >= i; j--)
{
hit[j]++;
}
j = get2byte(data, i);
Debug.Assert(j == 0 || j > i + size); /* Enforced by btreeInitPage() */
Debug.Assert(j <= usableSize - 4); /* Enforced by btreeInitPage() */
i = j;
}
for (i = cnt = 0; i < usableSize; i++)
{
if (hit[i] == 0)
{
cnt++;
}
else if (hit[i] > 1)
{
checkAppendMsg(pCheck, "",
"Multiple uses for byte %d of page %d", i, iPage);
break;
}
}
if (cnt != data[hdr + 7])
{
checkAppendMsg(pCheck, "",
"Fragmentation of %d bytes reported as %d on page %d",
cnt, data[hdr + 7], iPage);
}
}
sqlite3PageFree(ref hit);
releasePage(pPage);
return(depth + 1);
}
internal RC clearCell(int pCell)
{
Debug.Assert(MutexEx.Held(this.Shared.Mutex));
var info = new CellInfo();
btreeParseCellPtr(pCell, ref info);
if (info.iOverflow == 0)
{
return(RC.OK); // No overflow pages. Return without doing anything
}
var pBt = this.Shared;
var ovflPgno = (Pgno)ConvertEx.Get4(this.Data, pCell + info.iOverflow);
Debug.Assert(pBt.UsableSize > 4);
var ovflPageSize = (uint)(pBt.UsableSize - 4);
var nOvfl = (int)((info.nPayload - info.nLocal + ovflPageSize - 1) / ovflPageSize);
Debug.Assert(ovflPgno == 0 || nOvfl > 0);
RC rc;
while (nOvfl-- != 0)
{
Pgno iNext = 0;
MemPage pOvfl = null;
if (ovflPgno < 2 || ovflPgno > pBt.btreePagecount())
{
// 0 is not a legal page number and page 1 cannot be an overflow page. Therefore if ovflPgno<2 or past the end of the file the database must be corrupt.
return(SysEx.SQLITE_CORRUPT_BKPT());
}
if (nOvfl != 0)
{
rc = pBt.getOverflowPage(ovflPgno, out pOvfl, out iNext);
if (rc != RC.OK)
{
return(rc);
}
}
if ((pOvfl != null || ((pOvfl = pBt.btreePageLookup(ovflPgno)) != null)) && Pager.GetPageRefCount(pOvfl.DbPage) != 1)
{
// There is no reason any cursor should have an outstanding reference to an overflow page belonging to a cell that is being deleted/updated.
// So if there exists more than one reference to this page, then it must not really be an overflow page and the database must be corrupt.
// It is helpful to detect this before calling freePage2(), as freePage2() may zero the page contents if secure-delete mode is
// enabled. If this 'overflow' page happens to be a page that the caller is iterating through or using in some other way, this
// can be problematic.
rc = SysEx.SQLITE_CORRUPT_BKPT();
}
else
{
rc = pBt.freePage2(pOvfl, ovflPgno);
}
if (pOvfl != null)
{
Pager.Unref(pOvfl.DbPage);
}
if (rc != RC.OK)
{
return(rc);
}
ovflPgno = iNext;
}
return(RC.OK);
}
internal static void copyNodeContent(MemPage pFrom, MemPage pTo, ref RC pRC)
{
if (pRC != RC.OK)
return;
var pBt = pFrom.Shared;
var aFrom = pFrom.Data;
var aTo = pTo.Data;
var iFromHdr = pFrom.HeaderOffset;
var iToHdr = (pTo.ID == 1 ? 100 : 0);
Debug.Assert(pFrom.HasInit);
Debug.Assert(pFrom.FreeBytes >= iToHdr);
Debug.Assert(ConvertEx.Get2(aFrom, iFromHdr + 5) <= (int)pBt.UsableSize);
// Copy the b-tree node content from page pFrom to page pTo.
var iData = (int)ConvertEx.Get2(aFrom, iFromHdr + 5);
Buffer.BlockCopy(aFrom, iData, aTo, iData, (int)pBt.UsableSize - iData);
Buffer.BlockCopy(aFrom, iFromHdr, aTo, iToHdr, pFrom.CellOffset + 2 * pFrom.Cells);
// Reinitialize page pTo so that the contents of the MemPage structure match the new data. The initialization of pTo can actually fail under
// fairly obscure circumstances, even though it is a copy of initialized page pFrom.
pTo.HasInit = false;
var rc = pTo.btreeInitPage();
if (rc != RC.OK)
{
pRC = rc;
return;
}
// If this is an auto-vacuum database, update the pointer-map entries for any b-tree or overflow pages that pTo now contains the pointers to.
#if !SQLITE_OMIT_AUTOVACUUM
if (pBt.AutoVacuum)
#else
if (false)
#endif
{
pRC = pTo.setChildPtrmaps();
}
}
internal static RC balance_nonroot(MemPage pParent, int iParentIdx, byte[] aOvflSpace, int isRoot)
{
var apOld = new MemPage[NB]; // pPage and up to two siblings
var apCopy = new MemPage[NB]; // Private copies of apOld[] pages
var apNew = new MemPage[NB + 2];// pPage and up to NB siblings after balancing
var apDiv = new int[NB - 1]; // Divider cells in pParent
var cntNew = new int[NB + 2]; // Index in aCell[] of cell after i-th page
var szNew = new int[NB + 2]; // Combined size of cells place on i-th page
var szCell = new ushort[1]; // Local size of all cells in apCell[]
BtShared pBt; // The whole database
int nCell = 0; // Number of cells in apCell[]
int nMaxCells = 0; // Allocated size of apCell, szCell, aFrom.
int nNew = 0; // Number of pages in apNew[]
ushort leafCorrection; // 4 if pPage is a leaf. 0 if not
int leafData; // True if pPage is a leaf of a LEAFDATA tree
int usableSpace; // Bytes in pPage beyond the header
int pageFlags; // Value of pPage.aData[0]
int subtotal; // Subtotal of bytes in cells on one page
int iOvflSpace = 0; // First unused byte of aOvflSpace[]
//int szScratch; // Size of scratch memory requested
byte[][] apCell = null; // All cells begin balanced
//
pBt = pParent.Shared;
Debug.Assert(MutexEx.Held(pBt.Mutex));
Debug.Assert(Pager.IsPageWriteable(pParent.DbPage));
#if false
Btree.TRACE("BALANCE: begin page %d child of %d\n", pPage.pgno, pParent.pgno);
#endif
// At this point pParent may have at most one overflow cell. And if this overflow cell is present, it must be the cell with
// index iParentIdx. This scenario comes about when this function is called (indirectly) from sqlite3BtreeDelete().
Debug.Assert(pParent.NOverflows == 0 || pParent.NOverflows == 1);
Debug.Assert(pParent.NOverflows == 0 || pParent.Overflows[0].Index == iParentIdx);
// Find the sibling pages to balance. Also locate the cells in pParent that divide the siblings. An attempt is made to find NN siblings on
// either side of pPage. More siblings are taken from one side, however, if there are fewer than NN siblings on the other side. If pParent
// has NB or fewer children then all children of pParent are taken.
// This loop also drops the divider cells from the parent page. This way, the remainder of the function does not have to deal with any
// overflow cells in the parent page, since if any existed they will have already been removed.
int nOld; // Number of pages in apOld[]
int nxDiv; // Next divider slot in pParent.aCell[]
var i = pParent.NOverflows + pParent.Cells;
if (i < 2)
{
nxDiv = 0;
nOld = i + 1;
}
else
{
nOld = 3;
if (iParentIdx == 0)
nxDiv = 0;
else if (iParentIdx == i)
nxDiv = i - 2;
else
nxDiv = iParentIdx - 1;
i = 2;
}
var pRight = ((i + nxDiv - pParent.NOverflows) == pParent.Cells ? pParent.HeaderOffset + 8 : pParent.FindCell(i + nxDiv - pParent.NOverflows)); // Location in parent of right-sibling pointer
var pgno = (Pgno)ConvertEx.Get4(pParent.Data, pRight);
var rc = RC.OK;
while (true)
{
rc = pBt.getAndInitPage(pgno, ref apOld[i]);
if (rc != RC.OK)
goto balance_cleanup;
nMaxCells += 1 + apOld[i].Cells + apOld[i].NOverflows;
if (i-- == 0)
break;
if (i + nxDiv == pParent.Overflows[0].Index && pParent.NOverflows != 0)
{
apDiv[i] = 0;
pgno = ConvertEx.Get4(pParent.Overflows[0].Cell, apDiv[i]);
szNew[i] = pParent.cellSizePtr(apDiv[i]);
pParent.NOverflows = 0;
}
else
{
apDiv[i] = pParent.FindCell(i + nxDiv - pParent.NOverflows);
pgno = ConvertEx.Get4(pParent.Data, apDiv[i]);
szNew[i] = pParent.cellSizePtr(apDiv[i]);
// Drop the cell from the parent page. apDiv[i] still points to the cell within the parent, even though it has been dropped.
// This is safe because dropping a cell only overwrites the first four bytes of it, and this function does not need the first
// four bytes of the divider cell. So the pointer is safe to use later on.
//
// Unless SQLite is compiled in secure-delete mode. In this case, the dropCell() routine will overwrite the entire cell with zeroes.
// In this case, temporarily copy the cell into the aOvflSpace[] buffer. It will be copied out again as soon as the aSpace[] buffer
// is allocated.
//if (pBt.secureDelete)
//{
// int iOff = (int)(apDiv[i]) - (int)(pParent.aData); //SQLITE_PTR_TO_INT(apDiv[i]) - SQLITE_PTR_TO_INT(pParent.aData);
// if( (iOff+szNew[i])>(int)pBt->usableSize )
// {
// rc = SQLITE_CORRUPT_BKPT();
// Array.Clear(apOld[0].aData,0,apOld[0].aData.Length); //memset(apOld, 0, (i + 1) * sizeof(MemPage*));
// goto balance_cleanup;
// }
// else
// {
// memcpy(&aOvflSpace[iOff], apDiv[i], szNew[i]);
// apDiv[i] = &aOvflSpace[apDiv[i] - pParent.aData];
// }
//}
pParent.dropCell(i + nxDiv - pParent.NOverflows, szNew[i], ref rc);
}
}
// Make nMaxCells a multiple of 4 in order to preserve 8-byte alignment
nMaxCells = (nMaxCells + 3) & ~3;
// Allocate space for memory structures
apCell = MallocEx.sqlite3ScratchMalloc(apCell, nMaxCells);
if (szCell.Length < nMaxCells)
Array.Resize(ref szCell, nMaxCells);
// Load pointers to all cells on sibling pages and the divider cells into the local apCell[] array. Make copies of the divider cells
// into space obtained from aSpace1[] and remove the the divider Cells from pParent.
// If the siblings are on leaf pages, then the child pointers of the divider cells are stripped from the cells before they are copied
// into aSpace1[]. In this way, all cells in apCell[] are without child pointers. If siblings are not leaves, then all cell in
// apCell[] include child pointers. Either way, all cells in apCell[] are alike.
// leafCorrection: 4 if pPage is a leaf. 0 if pPage is not a leaf.
// leafData: 1 if pPage holds key+data and pParent holds only keys.
leafCorrection = (ushort)(apOld[0].Leaf * 4);
leafData = apOld[0].HasData;
int j;
for (i = 0; i < nOld; i++)
{
// Before doing anything else, take a copy of the i'th original sibling The rest of this function will use data from the copies rather
// that the original pages since the original pages will be in the process of being overwritten.
var pOld = apCopy[i] = apOld[i].Clone();
var limit = pOld.Cells + pOld.NOverflows;
if (pOld.NOverflows > 0 || true)
{
for (j = 0; j < limit; j++)
{
Debug.Assert(nCell < nMaxCells);
var iFOFC = pOld.FindOverflowCell(j);
szCell[nCell] = pOld.cellSizePtr(iFOFC);
// Copy the Data Locally
if (apCell[nCell] == null)
apCell[nCell] = new byte[szCell[nCell]];
else if (apCell[nCell].Length < szCell[nCell])
Array.Resize(ref apCell[nCell], szCell[nCell]);
if (iFOFC < 0) // Overflow Cell
Buffer.BlockCopy(pOld.Overflows[-(iFOFC + 1)].Cell, 0, apCell[nCell], 0, szCell[nCell]);
else
Buffer.BlockCopy(pOld.Data, iFOFC, apCell[nCell], 0, szCell[nCell]);
nCell++;
}
}
else
{
var aData = pOld.Data;
var maskPage = pOld.MaskPage;
var cellOffset = pOld.CellOffset;
for (j = 0; j < limit; j++)
{
Debugger.Break();
Debug.Assert(nCell < nMaxCells);
apCell[nCell] = FindCellv2(aData, maskPage, cellOffset, j);
szCell[nCell] = pOld.cellSizePtr(apCell[nCell]);
nCell++;
}
}
if (i < nOld - 1 && 0 == leafData)
{
var sz = (ushort)szNew[i];
var pTemp = MallocEx.sqlite3Malloc(sz + leafCorrection);
Debug.Assert(nCell < nMaxCells);
szCell[nCell] = sz;
Debug.Assert(sz <= pBt.MaxLocal + 23);
Buffer.BlockCopy(pParent.Data, apDiv[i], pTemp, 0, sz);
if (apCell[nCell] == null || apCell[nCell].Length < sz)
Array.Resize(ref apCell[nCell], sz);
Buffer.BlockCopy(pTemp, leafCorrection, apCell[nCell], 0, sz);
Debug.Assert(leafCorrection == 0 || leafCorrection == 4);
szCell[nCell] = (ushort)(szCell[nCell] - leafCorrection);
if (0 == pOld.Leaf)
{
Debug.Assert(leafCorrection == 0);
Debug.Assert(pOld.HeaderOffset == 0);
// The right pointer of the child page pOld becomes the left pointer of the divider cell
Buffer.BlockCopy(pOld.Data, 8, apCell[nCell], 0, 4);//memcpy( apCell[nCell], ref pOld.aData[8], 4 );
}
else
{
Debug.Assert(leafCorrection == 4);
if (szCell[nCell] < 4)
// Do not allow any cells smaller than 4 bytes.
szCell[nCell] = 4;
}
nCell++;
}
}
// Figure out the number of pages needed to hold all nCell cells. Store this number in "k". Also compute szNew[] which is the total
// size of all cells on the i-th page and cntNew[] which is the index in apCell[] of the cell that divides page i from page i+1.
// cntNew[k] should equal nCell.
// Values computed by this block:
// k: The total number of sibling pages
// szNew[i]: Spaced used on the i-th sibling page.
// cntNew[i]: Index in apCell[] and szCell[] for the first cell to
// the right of the i-th sibling page.
// usableSpace: Number of bytes of space available on each sibling.
usableSpace = (int)pBt.UsableSize - 12 + leafCorrection;
int k;
for (subtotal = k = i = 0; i < nCell; i++)
{
Debug.Assert(i < nMaxCells);
subtotal += szCell[i] + 2;
if (subtotal > usableSpace)
{
szNew[k] = subtotal - szCell[i];
cntNew[k] = i;
if (leafData != 0)
i--;
subtotal = 0;
k++;
if (k > NB + 1)
{
rc = SysEx.SQLITE_CORRUPT_BKPT();
goto balance_cleanup;
}
}
}
szNew[k] = subtotal;
cntNew[k] = nCell;
k++;
// The packing computed by the previous block is biased toward the siblings on the left side. The left siblings are always nearly full, while the
// right-most sibling might be nearly empty. This block of code attempts to adjust the packing of siblings to get a better balance.
//
// This adjustment is more than an optimization. The packing above might be so out of balance as to be illegal. For example, the right-most
// sibling might be completely empty. This adjustment is not optional.
for (i = k - 1; i > 0; i--)
{
var szRight = szNew[i]; // Size of sibling on the right
var szLeft = szNew[i - 1]; // Size of sibling on the left
var r = cntNew[i - 1] - 1; // Index of right-most cell in left sibling
var d = r + 1 - leafData; // Index of first cell to the left of right sibling
Debug.Assert(d < nMaxCells);
Debug.Assert(r < nMaxCells);
while (szRight == 0 || szRight + szCell[d] + 2 <= szLeft - (szCell[r] + 2))
{
szRight += szCell[d] + 2;
szLeft -= szCell[r] + 2;
cntNew[i - 1]--;
r = cntNew[i - 1] - 1;
d = r + 1 - leafData;
}
szNew[i] = szRight;
szNew[i - 1] = szLeft;
}
// Either we found one or more cells (cntnew[0])>0) or pPage is a virtual root page. A virtual root page is when the real root
// page is page 1 and we are the only child of that page.
Debug.Assert(cntNew[0] > 0 || (pParent.ID == 1 && pParent.Cells == 0));
Btree.TRACE("BALANCE: old: %d %d %d ", apOld[0].ID, (nOld >= 2 ? apOld[1].ID : 0), (nOld >= 3 ? apOld[2].ID : 0));
// Allocate k new pages. Reuse old pages where possible.
if (apOld[0].ID <= 1)
{
rc = SysEx.SQLITE_CORRUPT_BKPT();
goto balance_cleanup;
}
pageFlags = apOld[0].Data[0];
for (i = 0; i < k; i++)
{
var pNew = new MemPage();
if (i < nOld)
{
pNew = apNew[i] = apOld[i];
apOld[i] = null;
rc = Pager.Write(pNew.DbPage);
nNew++;
if (rc != RC.OK)
goto balance_cleanup;
}
else
{
Debug.Assert(i > 0);
rc = pBt.allocateBtreePage(ref pNew, ref pgno, pgno, 0);
if (rc != 0)
goto balance_cleanup;
apNew[i] = pNew;
nNew++;
// Set the pointer-map entry for the new sibling page.
#if !SQLITE_OMIT_AUTOVACUUM
if (pBt.AutoVacuum)
#else
if (false)
#endif
{
pBt.ptrmapPut(pNew.ID, PTRMAP.BTREE, pParent.ID, ref rc);
if (rc != RC.OK)
goto balance_cleanup;
}
}
}
// Free any old pages that were not reused as new pages.
while (i < nOld)
{
apOld[i].freePage(ref rc);
if (rc != RC.OK)
goto balance_cleanup;
apOld[i].releasePage();
apOld[i] = null;
i++;
}
// Put the new pages in accending order. This helps to keep entries in the disk file in order so that a scan
// of the table is a linear scan through the file. That in turn helps the operating system to deliver pages
// from the disk more rapidly.
// An O(n^2) insertion sort algorithm is used, but since n is never more than NB (a small constant), that should
// not be a problem.
// When NB==3, this one optimization makes the database about 25% faster for large insertions and deletions.
for (i = 0; i < k - 1; i++)
{
var minV = (int)apNew[i].ID;
var minI = i;
for (j = i + 1; j < k; j++)
if (apNew[j].ID < (uint)minV)
{
minI = j;
minV = (int)apNew[j].ID;
}
if (minI > i)
{
var pT = apNew[i];
apNew[i] = apNew[minI];
apNew[minI] = pT;
}
}
Btree.TRACE("new: %d(%d) %d(%d) %d(%d) %d(%d) %d(%d)\n", apNew[0].ID, szNew[0],
(nNew >= 2 ? apNew[1].ID : 0), (nNew >= 2 ? szNew[1] : 0),
(nNew >= 3 ? apNew[2].ID : 0), (nNew >= 3 ? szNew[2] : 0),
(nNew >= 4 ? apNew[3].ID : 0), (nNew >= 4 ? szNew[3] : 0),
(nNew >= 5 ? apNew[4].ID : 0), (nNew >= 5 ? szNew[4] : 0));
Debug.Assert(Pager.IsPageWriteable(pParent.DbPage));
ConvertEx.Put4L(pParent.Data, pRight, apNew[nNew - 1].ID);
// Evenly distribute the data in apCell[] across the new pages. Insert divider cells into pParent as necessary.
j = 0;
for (i = 0; i < nNew; i++)
{
// Assemble the new sibling page.
MemPage pNew = apNew[i];
Debug.Assert(j < nMaxCells);
pNew.zeroPage(pageFlags);
pNew.assemblePage(cntNew[i] - j, apCell, szCell, j);
Debug.Assert(pNew.Cells > 0 || (nNew == 1 && cntNew[0] == 0));
Debug.Assert(pNew.NOverflows == 0);
j = cntNew[i];
// If the sibling page assembled above was not the right-most sibling, insert a divider cell into the parent page.
Debug.Assert(i < nNew - 1 || j == nCell);
if (j < nCell)
{
Debug.Assert(j < nMaxCells);
var pCell = apCell[j];
var sz = szCell[j] + leafCorrection;
var pTemp = MallocEx.sqlite3Malloc(sz);
if (pNew.Leaf == 0)
Buffer.BlockCopy(pCell, 0, pNew.Data, 8, 4);
else if (leafData != 0)
{
// If the tree is a leaf-data tree, and the siblings are leaves, then there is no divider cell in apCell[]. Instead, the divider
// cell consists of the integer key for the right-most cell of the sibling-page assembled above only.
var info = new CellInfo();
j--;
pNew.btreeParseCellPtr(apCell[j], ref info);
pCell = pTemp;
sz = 4 + ConvertEx.PutVarint9L(pCell, 4, (ulong)info.nKey);
pTemp = null;
}
else
{
//------------ pCell -= 4;
var _pCell_4 = MallocEx.sqlite3Malloc(pCell.Length + 4);
Buffer.BlockCopy(pCell, 0, _pCell_4, 4, pCell.Length);
pCell = _pCell_4;
// Obscure case for non-leaf-data trees: If the cell at pCell was previously stored on a leaf node, and its reported size was 4
// bytes, then it may actually be smaller than this (see btreeParseCellPtr(), 4 bytes is the minimum size of
// any cell). But it is important to pass the correct size to insertCell(), so reparse the cell now.
// Note that this can never happen in an SQLite data file, as all cells are at least 4 bytes. It only happens in b-trees used
// to evaluate "IN (SELECT ...)" and similar clauses.
if (szCell[j] == 4)
{
Debug.Assert(leafCorrection == 4);
sz = pParent.cellSizePtr(pCell);
}
}
iOvflSpace += sz;
Debug.Assert(sz <= pBt.MaxLocal + 23);
Debug.Assert(iOvflSpace <= (int)pBt.PageSize);
pParent.insertCell(nxDiv, pCell, sz, pTemp, pNew.ID, ref rc);
if (rc != RC.OK)
goto balance_cleanup;
Debug.Assert(Pager.IsPageWriteable(pParent.DbPage));
j++;
nxDiv++;
}
}
Debug.Assert(j == nCell);
Debug.Assert(nOld > 0);
Debug.Assert(nNew > 0);
if ((pageFlags & Btree.PTF_LEAF) == 0)
Buffer.BlockCopy(apCopy[nOld - 1].Data, 8, apNew[nNew - 1].Data, 8, 4);
if (isRoot != 0 && pParent.Cells == 0 && pParent.HeaderOffset <= apNew[0].FreeBytes)
{
// The root page of the b-tree now contains no cells. The only sibling page is the right-child of the parent. Copy the contents of the
// child page into the parent, decreasing the overall height of the b-tree structure by one. This is described as the "balance-shallower"
// sub-algorithm in some documentation.
// If this is an auto-vacuum database, the call to copyNodeContent() sets all pointer-map entries corresponding to database image pages
// for which the pointer is stored within the content being copied.
// The second Debug.Assert below verifies that the child page is defragmented (it must be, as it was just reconstructed using assemblePage()). This
// is important if the parent page happens to be page 1 of the database image. */
Debug.Assert(nNew == 1);
Debug.Assert(apNew[0].FreeBytes == (ConvertEx.Get2(apNew[0].Data, 5) - apNew[0].CellOffset - apNew[0].Cells * 2));
copyNodeContent(apNew[0], pParent, ref rc);
apNew[0].freePage(ref rc);
}
else
#if !SQLITE_OMIT_AUTOVACUUM
if (pBt.AutoVacuum)
#else
if (false)
#endif
{
// Fix the pointer-map entries for all the cells that were shifted around. There are several different types of pointer-map entries that need to
// be dealt with by this routine. Some of these have been set already, but many have not. The following is a summary:
// 1) The entries associated with new sibling pages that were not siblings when this function was called. These have already
// been set. We don't need to worry about old siblings that were moved to the free-list - the freePage() code has taken care
// of those.
// 2) The pointer-map entries associated with the first overflow page in any overflow chains used by new divider cells. These
// have also already been taken care of by the insertCell() code.
// 3) If the sibling pages are not leaves, then the child pages of cells stored on the sibling pages may need to be updated.
// 4) If the sibling pages are not internal intkey nodes, then any overflow pages used by these cells may need to be updated
// (internal intkey nodes never contain pointers to overflow pages).
// 5) If the sibling pages are not leaves, then the pointer-map entries for the right-child pages of each sibling may need
// to be updated.
// Cases 1 and 2 are dealt with above by other code. The next block deals with cases 3 and 4 and the one after that, case 5. Since
// setting a pointer map entry is a relatively expensive operation, this code only sets pointer map entries for child or overflow pages that have
// actually moved between pages.
var pNew = apNew[0];
var pOld = apCopy[0];
var nOverflow = pOld.NOverflows;
var iNextOld = pOld.Cells + nOverflow;
var iOverflow = (nOverflow != 0 ? pOld.Overflows[0].Index : -1);
j = 0; // Current 'old' sibling page
k = 0; // Current 'new' sibling page
for (i = 0; i < nCell; i++)
{
var isDivider = 0;
while (i == iNextOld)
{
// Cell i is the cell immediately following the last cell on old sibling page j. If the siblings are not leaf pages of an
// intkey b-tree, then cell i was a divider cell.
pOld = apCopy[++j];
iNextOld = i + (0 == leafData ? 1 : 0) + pOld.Cells + pOld.NOverflows;
if (pOld.NOverflows != 0)
{
nOverflow = pOld.NOverflows;
iOverflow = i + (0 == leafData ? 1 : 0) + pOld.Overflows[0].Index;
}
isDivider = 0 == leafData ? 1 : 0;
}
Debug.Assert(nOverflow > 0 || iOverflow < i);
Debug.Assert(nOverflow < 2 || pOld.Overflows[0].Index == pOld.Overflows[1].Index - 1);
Debug.Assert(nOverflow < 3 || pOld.Overflows[1].Index == pOld.Overflows[2].Index - 1);
if (i == iOverflow)
{
isDivider = 1;
if (--nOverflow > 0)
iOverflow++;
}
if (i == cntNew[k])
{
// Cell i is the cell immediately following the last cell on new sibling page k. If the siblings are not leaf pages of an
// intkey b-tree, then cell i is a divider cell.
pNew = apNew[++k];
if (leafData == 0)
continue;
}
Debug.Assert(j < nOld);
Debug.Assert(k < nNew);
// If the cell was originally divider cell (and is not now) or an overflow cell, or if the cell was located on a different sibling
// page before the balancing, then the pointer map entries associated with any child or overflow pages need to be updated.
if (isDivider != 0 || pOld.ID != pNew.ID)
{
if (leafCorrection == 0)
pBt.ptrmapPut(ConvertEx.Get4(apCell[i]), PTRMAP.BTREE, pNew.ID, ref rc);
if (szCell[i] > pNew.MinLocal)
pNew.ptrmapPutOvflPtr(apCell[i], ref rc);
}
}
if (leafCorrection == 0)
for (i = 0; i < nNew; i++)
{
var key = ConvertEx.Get4(apNew[i].Data, 8);
pBt.ptrmapPut(key, PTRMAP.BTREE, apNew[i].ID, ref rc);
}
#if false
// The ptrmapCheckPages() contains Debug.Assert() statements that verify that all pointer map pages are set correctly. This is helpful while
// debugging. This is usually disabled because a corrupt database may cause an Debug.Assert() statement to fail.
ptrmapCheckPages(apNew, nNew);
ptrmapCheckPages(pParent, 1);
#endif
}
Debug.Assert(pParent.HasInit);
Btree.TRACE("BALANCE: finished: old=%d new=%d cells=%d\n", nOld, nNew, nCell);
// Cleanup before returning.
balance_cleanup:
MallocEx.sqlite3ScratchFree(apCell);
for (i = 0; i < nOld; i++)
apOld[i].releasePage();
for (i = 0; i < nNew; i++)
apNew[i].releasePage();
return rc;
}
internal static RC incrVacuumStep(BtShared pBt, Pgno nFin, Pgno iLastPg)
{
Pgno nFreeList; // Number of pages still on the free-list
Debug.Assert(MutexEx.Held(pBt.Mutex));
Debug.Assert(iLastPg > nFin);
if (!PTRMAP_ISPAGE(pBt, iLastPg) && iLastPg != PENDING_BYTE_PAGE(pBt))
{
PTRMAP eType = 0;
Pgno iPtrPage = 0;
nFreeList = ConvertEx.Get4(pBt.Page1.Data, 36);
if (nFreeList == 0)
return RC.DONE;
var rc = pBt.ptrmapGet( iLastPg, ref eType, ref iPtrPage);
if (rc != RC.OK)
return rc;
if (eType == PTRMAP.ROOTPAGE)
return SysEx.SQLITE_CORRUPT_BKPT();
if (eType == PTRMAP.FREEPAGE)
{
if (nFin == 0)
{
// Remove the page from the files free-list. This is not required if nFin is non-zero. In that case, the free-list will be
// truncated to zero after this function returns, so it doesn't matter if it still contains some garbage entries.
Pgno iFreePg = 0;
var pFreePg = new MemPage();
rc = pBt.allocateBtreePage( ref pFreePg, ref iFreePg, iLastPg, 1);
if (rc != RC.OK)
return rc;
Debug.Assert(iFreePg == iLastPg);
pFreePg.releasePage();
}
}
else
{
Pgno iFreePg = 0; // Index of free page to move pLastPg to
var pLastPg = new MemPage();
rc = pBt.btreeGetPage( iLastPg, ref pLastPg, 0);
if (rc != RC.OK)
return rc;
// If nFin is zero, this loop runs exactly once and page pLastPg is swapped with the first free page pulled off the free list.
// On the other hand, if nFin is greater than zero, then keep looping until a free-page located within the first nFin pages of the file is found.
do
{
var pFreePg = new MemPage();
rc = pBt.allocateBtreePage(ref pFreePg, ref iFreePg, 0, 0);
if (rc != RC.OK)
{
pLastPg.releasePage();
return rc;
}
pFreePg.releasePage();
} while (nFin != 0 && iFreePg > nFin);
Debug.Assert(iFreePg < iLastPg);
rc = Pager.Write(pLastPg.DbPage);
if (rc == RC.OK)
rc = relocatePage(pBt, pLastPg, eType, iPtrPage, iFreePg, (nFin != 0) ? 1 : 0);
pLastPg.releasePage();
if (rc != RC.OK)
return rc;
}
}
if (nFin == 0)
{
iLastPg--;
while (iLastPg == PENDING_BYTE_PAGE(pBt) || PTRMAP_ISPAGE(pBt, iLastPg))
{
if (PTRMAP_ISPAGE(pBt, iLastPg))
{
var pPg = new MemPage();
var rc = pBt.btreeGetPage(iLastPg, ref pPg, 0);
if (rc != RC.OK)
return rc;
rc = Pager.Write(pPg.DbPage);
pPg.releasePage();
if (rc != RC.OK)
return rc;
}
iLastPg--;
}
pBt.Pager.TruncateImage(iLastPg);
pBt.Pages = iLastPg;
}
return RC.OK;
}
// was:balance
private RC Balance()
{
var rc = RC.OK;
var nMin = (int)this.Shared.UsableSize * 2 / 3;
var balance_quick_called = 0;
var balance_deeper_called = 0;
do
{
var pageID = this.PageID;
var page = this.Pages[pageID];
if (pageID == 0)
{
if (page.NOverflows != 0)
{
// The root page of the b-tree is overfull. In this case call the balance_deeper() function to create a new child for the root-page
// and copy the current contents of the root-page to it. The next iteration of the do-loop will balance the child page.
Debug.Assert((balance_deeper_called++) == 0);
rc = MemPage.balance_deeper(page, ref this.Pages[1]);
if (rc == RC.OK)
{
this.PageID = 1;
this.PagesIndexs[0] = 0;
this.PagesIndexs[1] = 0;
Debug.Assert(this.Pages[1].NOverflows != 0);
}
}
else
{
break;
}
}
else if (page.NOverflows == 0 && page.FreeBytes <= nMin)
{
break;
}
else
{
var pParent = this.Pages[pageID - 1];
var iIdx = this.PagesIndexs[pageID - 1];
rc = Pager.Write(pParent.DbPage);
if (rc == RC.OK)
{
#if !SQLITE_OMIT_QUICKBALANCE
if (page.HasData != 0 && page.NOverflows == 1 && page.Overflows[0].Index == page.Cells && pParent.ID != 1 && pParent.Cells == iIdx)
{
// Call balance_quick() to create a new sibling of pPage on which to store the overflow cell. balance_quick() inserts a new cell
// into pParent, which may cause pParent overflow. If this happens, the next interation of the do-loop will balance pParent
// use either balance_nonroot() or balance_deeper(). Until this happens, the overflow cell is stored in the aBalanceQuickSpace[]
// buffer.
// The purpose of the following Debug.Assert() is to check that only a single call to balance_quick() is made for each call to this
// function. If this were not verified, a subtle bug involving reuse of the aBalanceQuickSpace[] might sneak in.
Debug.Assert((balance_quick_called++) == 0);
rc = MemPage.balance_quick(pParent, page, _balanceQuickSpaces);
}
else
#endif
{
// In this case, call balance_nonroot() to redistribute cells between pPage and up to 2 of its sibling pages. This involves
// modifying the contents of pParent, which may cause pParent to become overfull or underfull. The next iteration of the do-loop
// will balance the parent page to correct this.
// If the parent page becomes overfull, the overflow cell or cells are stored in the pSpace buffer allocated immediately below.
// A subsequent iteration of the do-loop will deal with this by calling balance_nonroot() (balance_deeper() may be called first,
// but it doesn't deal with overflow cells - just moves them to a different page). Once this subsequent call to balance_nonroot()
// has completed, it is safe to release the pSpace buffer used by the previous call, as the overflow cell data will have been
// copied either into the body of a database page or into the new pSpace buffer passed to the latter call to balance_nonroot().
var pSpace = new byte[this.Shared.PageSize];// u8 pSpace = sqlite3PageMalloc( pCur.pBt.pageSize );
rc = MemPage.balance_nonroot(pParent, iIdx, null, pageID == 1 ? 1 : 0);
// The pSpace buffer will be freed after the next call to balance_nonroot(), or just before this function returns, whichever comes first.
}
}
page.NOverflows = 0;
// The next iteration of the do-loop balances the parent page.
page.releasePage();
this.PageID--;
}
} while (rc == RC.OK);
return(rc);
}
internal RC getOverflowPage(Pgno ovfl, out MemPage ppPage, out Pgno pPgnoNext)
{
Pgno next = 0;
MemPage pPage = null;
ppPage = null;
var rc = RC.OK;
Debug.Assert(MutexEx.Held(this.Mutex));
// Debug.Assert( pPgnoNext != 0);
#if !SQLITE_OMIT_AUTOVACUUM
// Try to find the next page in the overflow list using the autovacuum pointer-map pages. Guess that the next page in
// the overflow list is page number (ovfl+1). If that guess turns out to be wrong, fall back to loading the data of page
// number ovfl to determine the next page number.
if (this.AutoVacuum)
{
Pgno pgno = 0;
Pgno iGuess = ovfl + 1;
PTRMAP eType = 0;
while (MemPage.PTRMAP_ISPAGE(this, iGuess) || iGuess == MemPage.PENDING_BYTE_PAGE(this))
iGuess++;
if (iGuess <= btreePagecount())
{
rc = ptrmapGet(iGuess, ref eType, ref pgno);
if (rc == RC.OK && eType == PTRMAP.OVERFLOW2 && pgno == ovfl)
{
next = iGuess;
rc = RC.DONE;
}
}
}
#endif
Debug.Assert(next == 0 || rc == RC.DONE);
if (rc == RC.OK)
{
rc = btreeGetPage(ovfl, ref pPage, 0);
Debug.Assert(rc == RC.OK || pPage == null);
if (rc == RC.OK)
next = ConvertEx.Get4(pPage.Data);
}
pPgnoNext = next;
if (ppPage != null)
ppPage = pPage;
else
pPage.releasePage();
return (rc == RC.DONE ? RC.OK : rc);
}
