public void ToFile(StorageEnvironment env, string backupPath, CompressionLevel compression = CompressionLevel.Optimal, Action<string> infoNotify = null,
Action backupStarted = null)
{
if (env.Options.IncrementalBackupEnabled == false)
throw new InvalidOperationException("Incremental backup is disabled for this storage");
var pageNumberToPageInScratch = new Dictionary<long, long>();
if (infoNotify == null)
infoNotify = str => { };
var toDispose = new List<IDisposable>();
try
{
IncrementalBackupInfo backupInfo;
long lastWrittenLogPage = -1;
long lastWrittenLogFile = -1;
using (var txw = env.NewTransaction(TransactionFlags.ReadWrite))
{
backupInfo = env.HeaderAccessor.Get(ptr => ptr->IncrementalBackup);
if (env.Journal.CurrentFile != null)
{
lastWrittenLogFile = env.Journal.CurrentFile.Number;
lastWrittenLogPage = env.Journal.CurrentFile.WritePagePosition;
}
//txw.Commit(); - intentionally not committing
}
if (backupStarted != null)
backupStarted();
infoNotify("Voron - reading storage journals for snapshot pages");
var lastBackedUpFile = backupInfo.LastBackedUpJournal;
var lastBackedUpPage = backupInfo.LastBackedUpJournalPage;
var firstJournalToBackup = backupInfo.LastBackedUpJournal;
if (firstJournalToBackup == -1)
firstJournalToBackup = 0; // first time that we do incremental backup
var lastTransaction = new TransactionHeader { TransactionId = -1 };
var recoveryPager = env.Options.CreateScratchPager("min-inc-backup.scratch");
toDispose.Add(recoveryPager);
int recoveryPage = 0;
for (var journalNum = firstJournalToBackup; journalNum <= backupInfo.LastCreatedJournal; journalNum++)
{
lastBackedUpFile = journalNum;
var journalFile = IncrementalBackup.GetJournalFile(env, journalNum, backupInfo);
try
{
using (var filePager = env.Options.OpenJournalPager(journalNum))
{
var reader = new JournalReader(filePager, recoveryPager, 0, null, recoveryPage);
reader.MaxPageToRead = lastBackedUpPage = journalFile.JournalWriter.NumberOfAllocatedPages;
if (journalNum == lastWrittenLogFile) // set the last part of the log file we'll be reading
reader.MaxPageToRead = lastBackedUpPage = lastWrittenLogPage;
if (lastBackedUpPage == journalFile.JournalWriter.NumberOfAllocatedPages) // past the file size
{
// move to the next
lastBackedUpPage = -1;
lastBackedUpFile++;
}
if (journalNum == backupInfo.LastBackedUpJournal) // continue from last backup
reader.SetStartPage(backupInfo.LastBackedUpJournalPage);
TransactionHeader* lastJournalTxHeader = null;
while (reader.ReadOneTransaction(env.Options))
{
// read all transactions here
lastJournalTxHeader = reader.LastTransactionHeader;
}
if (lastJournalTxHeader != null)
lastTransaction = *lastJournalTxHeader;
recoveryPage = reader.RecoveryPage;
foreach (var pagePosition in reader.TransactionPageTranslation)
{
var pageInJournal = pagePosition.Value.JournalPos;
var page = recoveryPager.Read(pageInJournal);
pageNumberToPageInScratch[pagePosition.Key] = pageInJournal;
if (page.IsOverflow)
{
var numberOfOverflowPages = recoveryPager.GetNumberOfOverflowPages(page.OverflowSize);
for (int i = 1; i < numberOfOverflowPages; i++)
pageNumberToPageInScratch.Remove(page.PageNumber + i);
}
}
}
}
finally
{
journalFile.Release();
}
}
if (pageNumberToPageInScratch.Count == 0)
{
infoNotify("Voron - no changes since last backup, nothing to do");
return;
}
infoNotify("Voron - started writing snapshot file.");
if (lastTransaction.TransactionId == -1)
throw new InvalidOperationException("Could not find any transactions in the journals, but found pages to write? That ain't right.");
// it is possible that we merged enough transactions so the _merged_ output is too large for us.
// Voron limit transactions to about 4GB each. That means that we can't just merge all transactions
// blindly, for fear of hitting this limit. So we need to split things.
// We are also limited to about 8 TB of data in general before we literally can't fit the number of pages into
// pageNumberToPageInScratch even theoretically.
// We're fine with saying that you need to run min inc backup before you hit 8 TB in your increment, so that works for now.
// We are also going to use env.Options.MaxScratchBufferSize to set the actual transaction limit here, to avoid issues
// down the road and to limit how big a single transaction can be before the theoretical 4GB limit.
var nextJournalNum = lastBackedUpFile;
using (var file = new FileStream(backupPath, FileMode.Create))
{
using (var package = new ZipArchive(file, ZipArchiveMode.Create, leaveOpen: true))
{
var copier = new DataCopier(AbstractPager.PageSize * 16);
var finalPager = env.Options.CreateScratchPager("min-inc-backup-final.scratch");
toDispose.Add(finalPager);
finalPager.EnsureContinuous(null, 0, 1);//txHeader
foreach (var partition in Partition(pageNumberToPageInScratch.Values, env.Options.MaxNumberOfPagesInMergedTransaction))
{
int totalNumberOfPages = 0;
int overflowPages = 0;
int start = 1;
foreach (var pageNum in partition)
{
var p = recoveryPager.Read(pageNum);
var size = 1;
if (p.IsOverflow)
{
size = recoveryPager.GetNumberOfOverflowPages(p.OverflowSize);
overflowPages += (size - 1);
}
totalNumberOfPages += size;
finalPager.EnsureContinuous(null, start, size); //maybe increase size
Memory.Copy(finalPager.AcquirePagePointer(start), p.Base, size * AbstractPager.PageSize);
start += size;
}
var txPage = finalPager.AcquirePagePointer(0);
UnmanagedMemory.Set(txPage, 0, AbstractPager.PageSize);
var txHeader = (TransactionHeader*)txPage;
txHeader->HeaderMarker = Constants.TransactionHeaderMarker;
txHeader->FreeSpace = lastTransaction.FreeSpace;
txHeader->Root = lastTransaction.Root;
txHeader->OverflowPageCount = overflowPages;
txHeader->PageCount = totalNumberOfPages - overflowPages;
txHeader->PreviousTransactionCrc = lastTransaction.PreviousTransactionCrc;
txHeader->TransactionId = lastTransaction.TransactionId;
txHeader->NextPageNumber = lastTransaction.NextPageNumber;
txHeader->LastPageNumber = lastTransaction.LastPageNumber;
txHeader->TxMarker = TransactionMarker.Commit | TransactionMarker.Merged;
txHeader->Compressed = false;
txHeader->UncompressedSize = txHeader->CompressedSize = totalNumberOfPages * AbstractPager.PageSize;
txHeader->Crc = Crc.Value(finalPager.AcquirePagePointer(1), 0, totalNumberOfPages * AbstractPager.PageSize);
var entry = package.CreateEntry(string.Format("{0:D19}.merged-journal", nextJournalNum), compression);
nextJournalNum++;
using (var stream = entry.Open())
{
copier.ToStream(finalPager.AcquirePagePointer(0), (totalNumberOfPages + 1) * AbstractPager.PageSize, stream);
}
}
}
file.Flush(true);// make sure we hit the disk and stay there
}
env.HeaderAccessor.Modify(header =>
{
header->IncrementalBackup.LastBackedUpJournal = lastBackedUpFile;
header->IncrementalBackup.LastBackedUpJournalPage = lastBackedUpPage;
});
}
finally
{
foreach (var disposable in toDispose)
disposable.Dispose();
}
}
