public virtual RC Unlock(LOCK locktype)
{
Debug.Assert(locktype <= LOCK.SHARED);
#if DEBUG
SysEx.OSTRACE("UNLOCK {0} to {1} was {2}({3})", S.GetHashCode(), locktype, this.Locktype, SharedLockByte);
#endif
var rc = RC.OK;
var type = this.Locktype;
if (type >= LOCK.EXCLUSIVE)
{
lockingStrategy.UnlockFile(this, SHARED_FIRST, SHARED_SIZE);
if (locktype == LOCK.SHARED && getReadLock() == 0)
{
// This should never happen. We should always be able to reacquire the read lock
rc = winLogError(RC.IOERR_UNLOCK, "winUnlock", Path);
}
}
if (type >= LOCK.RESERVED)
{
try { lockingStrategy.UnlockFile(this, RESERVED_BYTE, 1); }
catch (Exception) { }
}
if (locktype == LOCK.NO && type >= LOCK.SHARED)
{
unlockReadLock();
}
if (type >= LOCK.PENDING)
{
try { lockingStrategy.UnlockFile(this, PENDING_BYTE, 1); }
catch (Exception) { }
}
this.Locktype = locktype;
return(rc);
}
public int Chunk; // Chunk size configured by FCNTL_CHUNK_SIZE
public void Clear()
{
S = null;
Locktype = 0;
SharedLockByte = 0;
LastErrno = 0;
_sectorSize = 0;
}
public Button(Sprite sprite, MouseInput mouseInput)
{
_buttonSprite = sprite;
_buttonSprite.BindParent(this);
_mouseInput = mouseInput;
_state = BUTTON_STATE.RELEASED;
_selection = BUTTON_SELECT.NONE;
_lock = LOCK.LOCKED;
}
public Button(Sprite sprite, MouseInput mouseInput)
{
_buttonSprite = sprite;
_buttonSprite.BindParent(this);
_mouseInput = mouseInput;
_state = BUTTON_STATE.RELEASED;
_selection = BUTTON_SELECT.NONE;
_lock = LOCK.LOCKED;
}
static bool hasSharedCacheTableLock(Btree btree, Pid root, bool isIndex, LOCK lockType)
{
// If this database is not shareable, or if the client is reading and has the read-uncommitted flag set, then no lock is required.
// Return true immediately.
if (!btree.Sharable_ || (lockType == LOCK.READ && (btree.Ctx.Flags & BContext.FLAG.ReadUncommitted) != 0))
return true;
// If the client is reading or writing an index and the schema is not loaded, then it is too difficult to actually check to see if
// the correct locks are held. So do not bother - just return true. This case does not come up very often anyhow.
var schema = btree.Bt.Schema;
if (isIndex && (schema == null || (schema.Flags & SCHEMA_.SchemaLoaded) == 0))
return true;
// Figure out the root-page that the lock should be held on. For table b-trees, this is just the root page of the b-tree being read or
// written. For index b-trees, it is the root page of the associated table.
Pid table = 0;
if (isIndex)
throw new NotImplementedException();
//for (var p = sqliteHashFirst(schema.IdxHash); p != null; p = sqliteHashNext(p))
//{
// var idx = (Index)sqliteHashData(p);
// if (idx.TID == (int)root)
// table = idx.Table.TID;
//}
else
table = root;
// Search for the required lock. Either a write-lock on root-page iTab, a write-lock on the schema table, or (if the client is reading) a
// read-lock on iTab will suffice. Return 1 if any of these are found.
for (var lock_ = btree.Bt.Lock; lock_ != null; lock_ = lock_.Next)
if (lock_.Btree == btree &&
(lock_.Table == table || (lock_.Lock == LOCK.WRITE && lock_.Table == 1)) &&
lock_.Lock >= lockType)
return true;
// Failed to find the required lock.
return false;
}
protected virtual void OnLock()
{
_lock = LOCK.LOCKED; OnDeselect();
}
static RC querySharedCacheTableLock(Btree p, Pid table, LOCK lock_) { return RC.OK; }
static RC querySharedCacheTableLock(Btree p, Pid table, LOCK lockType)
{
Debug.Assert(p.HoldsMutex());
Debug.Assert(lockType == LOCK.READ || lockType == LOCK.WRITE);
Debug.Assert(p.Ctx != null);
Debug.Assert((p.Ctx.Flags & BContext.FLAG.ReadUncommitted) == 0 || lockType == LOCK.WRITE || table == 1);
// If requesting a write-lock, then the Btree must have an open write transaction on this file. And, obviously, for this to be so there
// must be an open write transaction on the file itself.
var bt = p.Bt;
Debug.Assert(lockType == LOCK.READ || (p == bt.Writer && p.InTrans == TRANS.WRITE));
Debug.Assert(lockType == LOCK.READ || bt.InTransaction == TRANS.WRITE);
// This routine is a no-op if the shared-cache is not enabled
if (!p.Sharable_)
return RC.OK;
// If some other connection is holding an exclusive lock, the requested lock may not be obtained.
if (bt.Writer != p && (bt.BtsFlags & BTS.EXCLUSIVE) != 0)
{
BContext.ConnectionBlocked(p.Ctx, bt.Writer.Ctx);
return RC.LOCKED_SHAREDCACHE;
}
for (var iter = bt.Lock; iter != null; iter = iter.Next)
{
// The condition (pIter->eLock!=eLock) in the following if(...) statement is a simplification of:
//
// (eLock==WRITE_LOCK || pIter->eLock==WRITE_LOCK)
//
// since we know that if eLock==WRITE_LOCK, then no other connection may hold a WRITE_LOCK on any table in this file (since there can
// only be a single writer).
Debug.Assert(iter.Lock == LOCK.READ || iter.Lock == LOCK.WRITE);
Debug.Assert(lockType == LOCK.READ || iter.Btree == p || iter.Lock == LOCK.READ);
if (iter.Btree != p && iter.Table == table && iter.Lock != lockType)
{
BContext.ConnectionBlocked(p.Ctx, iter.Btree.Ctx);
if (lockType == LOCK.WRITE)
{
Debug.Assert(p == bt.Writer);
bt.BtsFlags |= BTS.PENDING;
}
return RC.LOCKED_SHAREDCACHE;
}
}
return RC.OK;
}
static RC setSharedCacheTableLock(Btree p, Pid table, LOCK lock_)
{
Debug.Assert(p.HoldsMutex());
Debug.Assert(lock_ == LOCK.READ || lock_ == LOCK.WRITE);
Debug.Assert(p.Ctx != null);
// A connection with the read-uncommitted flag set will never try to obtain a read-lock using this function. The only read-lock obtained
// by a connection in read-uncommitted mode is on the sqlite_master table, and that lock is obtained in BtreeBeginTrans().
Debug.Assert((p.Ctx.Flags & BContext.FLAG.ReadUncommitted) == 0 || lock_ == LOCK.WRITE);
// This function should only be called on a sharable b-tree after it has been determined that no other b-tree holds a conflicting lock.
var bt = p.Bt;
Debug.Assert(p.Sharable_);
Debug.Assert(RC.OK == querySharedCacheTableLock(p, table, lock_));
// First search the list for an existing lock on this table.
BtLock newLock = null;
for (var iter = bt.Lock; iter != null; iter = iter.Next)
if (iter.Table == table && iter.Btree == p)
{
newLock = iter;
break;
}
// If the above search did not find a BtLock struct associating Btree p with table iTable, allocate one and link it into the list.
if (newLock == null)
{
newLock = new BtLock();
newLock.Table = table;
newLock.Btree = p;
newLock.Next = bt.Lock;
bt.Lock = newLock;
}
// Set the BtLock.eLock variable to the maximum of the current lock and the requested lock. This means if a write-lock was already held
// and a read-lock requested, we don't incorrectly downgrade the lock.
Debug.Assert(LOCK.WRITE > LOCK.READ);
if (lock_ > newLock.Lock)
newLock.Lock = lock_;
return RC.OK;
}
public virtual RC Lock(LOCK locktype)
{
#if DEBUG
SysEx.OSTRACE("LOCK {0} {1} was {2}({3})", S.GetHashCode(), locktype, this.Locktype, SharedLockByte);
#endif
// If there is already a lock of this type or more restrictive on the OsFile, do nothing. Don't use the end_lock: exit path, as sqlite3OsEnterMutex() hasn't been called yet.
if (this.Locktype >= locktype)
return RC.OK;
// Make sure the locking sequence is correct
Debug.Assert(this.Locktype != LOCK.NO || locktype == LOCK.SHARED);
Debug.Assert(locktype != LOCK.PENDING);
Debug.Assert(locktype != LOCK.RESERVED || this.Locktype == LOCK.SHARED);
// Lock the PENDING_LOCK byte if we need to acquire a PENDING lock or a SHARED lock. If we are acquiring a SHARED lock, the acquisition of
// the PENDING_LOCK byte is temporary.
uint error = 0;
var res = 1; // Result of a windows lock call
var gotPendingLock = false; // True if we acquired a PENDING lock this time
var newLocktype = this.Locktype;
if (this.Locktype == LOCK.NO || (locktype == LOCK.EXCLUSIVE && this.Locktype == LOCK.RESERVED))
{
res = 0;
var cnt = 3;
while (cnt-- > 0 && res == 0)
try { lockingStrategy.LockFile(this, PENDING_BYTE, 1); res = 1; }
catch (Exception)
{
// Try 3 times to get the pending lock. The pending lock might be held by another reader process who will release it momentarily.
#if DEBUG
SysEx.OSTRACE("could not get a PENDING lock. cnt={0}", cnt);
#endif
Thread.Sleep(1);
}
gotPendingLock = (res != 0);
if (0 == res)
error = (uint)Marshal.GetLastWin32Error();
}
// Acquire a shared lock
if (locktype == LOCK.SHARED && res != 0)
{
Debug.Assert(this.Locktype == LOCK.NO);
res = getReadLock();
if (res != 0)
newLocktype = LOCK.SHARED;
else
error = (uint)Marshal.GetLastWin32Error();
}
// Acquire a RESERVED lock
if (locktype == LOCK.RESERVED && res != 0)
{
Debug.Assert(this.Locktype == LOCK.SHARED);
try { lockingStrategy.LockFile(this, RESERVED_BYTE, 1); newLocktype = LOCK.RESERVED; res = 1; }
catch (Exception) { res = 0; error = (uint)Marshal.GetLastWin32Error(); }
if (res != 0)
newLocktype = LOCK.RESERVED;
else
error = (uint)Marshal.GetLastWin32Error();
}
// Acquire a PENDING lock
if (locktype == LOCK.EXCLUSIVE && res != 0)
{
newLocktype = LOCK.PENDING;
gotPendingLock = false;
}
// Acquire an EXCLUSIVE lock
if (locktype == LOCK.EXCLUSIVE && res != 0)
{
Debug.Assert(this.Locktype >= LOCK.SHARED);
res = unlockReadLock();
#if DEBUG
SysEx.OSTRACE("unreadlock = {0}", res);
#endif
try { lockingStrategy.LockFile(this, SHARED_FIRST, SHARED_SIZE); newLocktype = LOCK.EXCLUSIVE; res = 1; }
catch (Exception) { res = 0; }
if (res != 0)
newLocktype = LOCK.EXCLUSIVE;
else
{
error = (uint)Marshal.GetLastWin32Error();
#if DEBUG
SysEx.OSTRACE("error-code = {0}", error);
#endif
getReadLock();
}
}
// If we are holding a PENDING lock that ought to be released, then release it now.
if (gotPendingLock && locktype == LOCK.SHARED)
lockingStrategy.UnlockFile(this, PENDING_BYTE, 1);
// Update the state of the lock has held in the file descriptor then return the appropriate result code.
var rc = RC.OK;
if (res != 0)
rc = RC.OK;
else
{
#if DEBUG
SysEx.OSTRACE("LOCK FAILED {0} trying for {1} but got {2}", S.GetHashCode(), locktype, newLocktype);
#endif
LastErrno = error;
rc = RC.BUSY;
}
this.Locktype = newLocktype;
return rc;
}
public override RC Unlock(LOCK locktype)
{
return(RC.OK);
}
public virtual void Lock()
{
_lock = LOCK.LOCKED;
OnLock();
}
public virtual RC Lock(LOCK locktype)
{
#if DEBUG
SysEx.OSTRACE("LOCK {0} {1} was {2}({3})", S.GetHashCode(), locktype, this.Locktype, SharedLockByte);
#endif
// If there is already a lock of this type or more restrictive on the OsFile, do nothing. Don't use the end_lock: exit path, as sqlite3OsEnterMutex() hasn't been called yet.
if (this.Locktype >= locktype)
{
return(RC.OK);
}
// Make sure the locking sequence is correct
Debug.Assert(this.Locktype != LOCK.NO || locktype == LOCK.SHARED);
Debug.Assert(locktype != LOCK.PENDING);
Debug.Assert(locktype != LOCK.RESERVED || this.Locktype == LOCK.SHARED);
// Lock the PENDING_LOCK byte if we need to acquire a PENDING lock or a SHARED lock. If we are acquiring a SHARED lock, the acquisition of
// the PENDING_LOCK byte is temporary.
uint error = 0;
var res = 1; // Result of a windows lock call
var gotPendingLock = false; // True if we acquired a PENDING lock this time
var newLocktype = this.Locktype;
if (this.Locktype == LOCK.NO || (locktype == LOCK.EXCLUSIVE && this.Locktype == LOCK.RESERVED))
{
res = 0;
var cnt = 3;
while (cnt-- > 0 && res == 0)
{
try { lockingStrategy.LockFile(this, PENDING_BYTE, 1); res = 1; }
catch (Exception)
{
// Try 3 times to get the pending lock. The pending lock might be held by another reader process who will release it momentarily.
#if DEBUG
SysEx.OSTRACE("could not get a PENDING lock. cnt={0}", cnt);
#endif
Thread.Sleep(1);
}
}
gotPendingLock = (res != 0);
if (0 == res)
{
error = (uint)Marshal.GetLastWin32Error();
}
}
// Acquire a shared lock
if (locktype == LOCK.SHARED && res != 0)
{
Debug.Assert(this.Locktype == LOCK.NO);
res = getReadLock();
if (res != 0)
{
newLocktype = LOCK.SHARED;
}
else
{
error = (uint)Marshal.GetLastWin32Error();
}
}
// Acquire a RESERVED lock
if (locktype == LOCK.RESERVED && res != 0)
{
Debug.Assert(this.Locktype == LOCK.SHARED);
try { lockingStrategy.LockFile(this, RESERVED_BYTE, 1); newLocktype = LOCK.RESERVED; res = 1; }
catch (Exception) { res = 0; error = (uint)Marshal.GetLastWin32Error(); }
if (res != 0)
{
newLocktype = LOCK.RESERVED;
}
else
{
error = (uint)Marshal.GetLastWin32Error();
}
}
// Acquire a PENDING lock
if (locktype == LOCK.EXCLUSIVE && res != 0)
{
newLocktype = LOCK.PENDING;
gotPendingLock = false;
}
// Acquire an EXCLUSIVE lock
if (locktype == LOCK.EXCLUSIVE && res != 0)
{
Debug.Assert(this.Locktype >= LOCK.SHARED);
res = unlockReadLock();
#if DEBUG
SysEx.OSTRACE("unreadlock = {0}", res);
#endif
try { lockingStrategy.LockFile(this, SHARED_FIRST, SHARED_SIZE); newLocktype = LOCK.EXCLUSIVE; res = 1; }
catch (Exception) { res = 0; }
if (res != 0)
{
newLocktype = LOCK.EXCLUSIVE;
}
else
{
error = (uint)Marshal.GetLastWin32Error();
#if DEBUG
SysEx.OSTRACE("error-code = {0}", error);
#endif
getReadLock();
}
}
// If we are holding a PENDING lock that ought to be released, then release it now.
if (gotPendingLock && locktype == LOCK.SHARED)
{
lockingStrategy.UnlockFile(this, PENDING_BYTE, 1);
}
// Update the state of the lock has held in the file descriptor then return the appropriate result code.
var rc = RC.OK;
if (res != 0)
{
rc = RC.OK;
}
else
{
#if DEBUG
SysEx.OSTRACE("LOCK FAILED {0} trying for {1} but got {2}", S.GetHashCode(), locktype, newLocktype);
#endif
LastErrno = error;
rc = RC.BUSY;
}
this.Locktype = newLocktype;
return(rc);
}
protected virtual void OnLock()
{
_lock = LOCK.LOCKED; OnDeselect();
}
protected virtual void OnUnlock()
{
_lock = LOCK.UNLOCKED;
}
public override RC Lock(LOCK locktype)
{
return RC.OK;
}
public virtual RC Lock(LOCK lock_)
{
return(RC.OK);
}
public virtual RC Unlock(LOCK locktype)
{
Debug.Assert(locktype <= LOCK.SHARED);
#if DEBUG
SysEx.OSTRACE("UNLOCK {0} to {1} was {2}({3})", S.GetHashCode(), locktype, this.Locktype, SharedLockByte);
#endif
var rc = RC.OK;
var type = this.Locktype;
if (type >= LOCK.EXCLUSIVE)
{
lockingStrategy.UnlockFile(this, SHARED_FIRST, SHARED_SIZE);
if (locktype == LOCK.SHARED && getReadLock() == 0)
// This should never happen. We should always be able to reacquire the read lock
rc = winLogError(RC.IOERR_UNLOCK, "winUnlock", Path);
}
if (type >= LOCK.RESERVED)
try { lockingStrategy.UnlockFile(this, RESERVED_BYTE, 1); }
catch (Exception) { }
if (locktype == LOCK.NO && type >= LOCK.SHARED)
unlockReadLock();
if (type >= LOCK.PENDING)
{
try { lockingStrategy.UnlockFile(this, PENDING_BYTE, 1); }
catch (Exception) { }
}
this.Locktype = locktype;
return rc;
}
protected virtual void OnUnlock()
{
_lock = LOCK.UNLOCKED;
}
public virtual void Unlock()
{
_lock = LOCK.UNLOCKED;
OnUnlock();
}
public virtual void Lock()
{
_lock = LOCK.LOCKED;
OnLock();
}
public void Clear()
{
S = null;
Locktype = 0;
SharedLockByte = 0;
LastErrno = 0;
_sectorSize = 0;
}
public virtual void Unlock()
{
_lock = LOCK.UNLOCKED;
OnUnlock();
}
public virtual RC Unlock(LOCK lock_)
{
return RC.OK;
}
