internal Page ModifyPage(long num)
{
_env.AssertNoCatastrophicFailure();
// Check if we can hit the lowest level locality cache.
Page currentPage = GetPage(num);
if (_dirtyPages.Contains(num))
{
return(currentPage);
}
int pageSize;
Page newPage;
if (currentPage.IsOverflow)
{
newPage = AllocateOverflowRawPage(currentPage.OverflowSize, num, currentPage, zeroPage: false);
pageSize = Environment.Options.PageSize *
DataPager.GetNumberOfOverflowPages(currentPage.OverflowSize);
}
else
{
newPage = AllocatePage(1, num, currentPage, zeroPage: false); // allocate new page in a log file but with the same number
pageSize = Environment.Options.PageSize;
}
Memory.BulkCopy(newPage.Pointer, currentPage.Pointer, pageSize);
TrackWritablePage(newPage);
return(newPage);
}
public LowLevelTransaction(StorageEnvironment env, long id, TransactionPersistentContext transactionPersistentContext, TransactionFlags flags, IFreeSpaceHandling freeSpaceHandling, ByteStringContext context = null)
{
env.AssertNoCatastrophicFailure();
DataPager = env.Options.DataPager;
_env = env;
_journal = env.Journal;
_id = id;
_freeSpaceHandling = freeSpaceHandling;
_allocator = context ?? new ByteStringContext();
_disposeAllocator = context == null;
_pagerStates = new HashSet <PagerState>(ReferenceEqualityComparer <PagerState> .Default);
PersistentContext = transactionPersistentContext;
Flags = flags;
PageSize = DataPager.PageSize;
var scratchPagerStates = env.ScratchBufferPool.GetPagerStatesOfAllScratches();
foreach (var scratchPagerState in scratchPagerStates.Values)
{
scratchPagerState.AddRef();
_pagerStates.Add(scratchPagerState);
}
if (flags != TransactionFlags.ReadWrite)
{
// for read transactions, we need to keep the pager state frozen
// for write transactions, we can use the current one (which == null)
_scratchPagerStates = scratchPagerStates;
_state = env.State.Clone();
InitializeRoots();
JournalSnapshots = _journal.GetSnapshots();
return;
}
EnsureNoDuplicateTransactionId(id);
_env.WriteTransactionPool.Reset();
_dirtyOverflowPages = _env.WriteTransactionPool.DirtyOverflowPagesPool;
_scratchPagesTable = _env.WriteTransactionPool.ScratchPagesTablePool;
_dirtyPages = _env.WriteTransactionPool.DirtyPagesPool;
_freedPages = new HashSet <long>(NumericEqualityComparer.Instance);
_unusedScratchPages = new List <PageFromScratchBuffer>();
_transactionPages = new HashSet <PageFromScratchBuffer>(PageFromScratchBufferEqualityComparer.Instance);
_pagesToFreeOnCommit = new Stack <long>();
_state = env.State.Clone();
InitializeRoots();
InitTransactionHeader();
}