/// <summary>
/// Provide device to store delta log for incremental snapshot checkpoints
/// </summary>
/// <param name="token"></param>
/// <returns></returns>
public IDevice GetDeltaLogDevice(Guid token)
{
return(Devices.CreateLogDevice(directoryConfiguration.GetDeltaLogFileName(token), false));
}
/// <summary>
/// Provide device to store index checkpoint (including overflow buckets)
/// </summary>
/// <param name="indexToken"></param>
/// <returns></returns>
public IDevice GetIndexDevice(Guid indexToken)
{
return(Devices.CreateLogDevice(directoryConfiguration.GetPrimaryHashTableFileName(indexToken), false));
}
/// <summary>
/// Provide device to store snapshot of object log (required only for snapshot checkpoints)
/// </summary>
/// <param name="token"></param>
/// <returns></returns>
public IDevice GetSnapshotObjectLogDevice(Guid token)
{
return(Devices.CreateLogDevice(directoryConfiguration.GetObjectLogSnapshotFileName(token), false));
}
private void RecoverHybridLogFromSnapshotFile(
IndexRecoveryInfo indexRecoveryInfo,
HybridLogRecoveryInfo recoveryInfo)
{
var fileStartAddress = recoveryInfo.flushedLogicalAddress;
var fromAddress = indexRecoveryInfo.startLogicalAddress;
var untilAddress = recoveryInfo.finalLogicalAddress;
// Compute startPage and endPage
var startPage = hlog.GetPage(fileStartAddress);
var endPage = hlog.GetPage(untilAddress);
if (untilAddress > hlog.GetStartLogicalAddress(endPage))
{
endPage++;
}
// By default first page has one extra record
var capacity = hlog.GetCapacityNumPages();
var recoveryDevice = Devices.CreateLogDevice(directoryConfiguration.GetHybridLogCheckpointFileName(recoveryInfo.guid), false);
var objectLogRecoveryDevice = Devices.CreateLogDevice(directoryConfiguration.GetHybridLogObjectCheckpointFileName(recoveryInfo.guid), false);
recoveryDevice.Initialize(hlog.GetSegmentSize());
objectLogRecoveryDevice.Initialize(hlog.GetSegmentSize());
var recoveryStatus = new RecoveryStatus(capacity, startPage, endPage)
{
recoveryDevice = recoveryDevice,
objectLogRecoveryDevice = objectLogRecoveryDevice,
recoveryDevicePageOffset = startPage
};
// Initially issue read request for all pages that can be held in memory
int totalPagesToRead = (int)(endPage - startPage);
int numPagesToReadFirst = Math.Min(capacity, totalPagesToRead);
hlog.AsyncReadPagesFromDevice(startPage, numPagesToReadFirst,
AsyncReadPagesCallbackForRecovery,
recoveryStatus,
recoveryStatus.recoveryDevicePageOffset,
recoveryStatus.recoveryDevice, recoveryStatus.objectLogRecoveryDevice);
for (long page = startPage; page < endPage; page++)
{
// Ensure the page is read from file
int pageIndex = hlog.GetPageIndexForPage(page);
while (recoveryStatus.readStatus[pageIndex] == ReadStatus.Pending)
{
Thread.Sleep(10);
}
// Page at hand
var startLogicalAddress = hlog.GetStartLogicalAddress(page);
var endLogicalAddress = hlog.GetStartLogicalAddress(page + 1);
// Perform recovery if page in fuzzy portion of the log
if ((fromAddress < endLogicalAddress) && (fromAddress < untilAddress))
{
/*
* Handling corner-cases:
* ----------------------
* When fromAddress is in the middle of the page,
* then start recovery only from corresponding offset
* in page. Similarly, if untilAddress falls in the
* middle of the page, perform recovery only until that
* offset. Otherwise, scan the entire page [0, PageSize)
*/
var pageFromAddress = 0L;
if (fromAddress > startLogicalAddress && fromAddress < endLogicalAddress)
{
pageFromAddress = hlog.GetOffsetInPage(fromAddress);
}
var pageUntilAddress = hlog.GetPageSize();
if (endLogicalAddress > untilAddress)
{
pageUntilAddress = hlog.GetOffsetInPage(untilAddress);
}
var physicalAddress = hlog.GetPhysicalAddress(startLogicalAddress);
RecoverFromPage(fromAddress, pageFromAddress, pageUntilAddress,
startLogicalAddress, physicalAddress, recoveryInfo.version);
}
// OS thread flushes current page and issues a read request if necessary
recoveryStatus.readStatus[pageIndex] = ReadStatus.Pending;
recoveryStatus.flushStatus[pageIndex] = FlushStatus.Pending;
// Write back records from snapshot to main hybrid log
hlog.AsyncFlushPages(page, 1, AsyncFlushPageCallbackForRecovery, recoveryStatus);
}
// Assert and wait until all pages have been flushed
var done = false;
while (!done)
{
done = true;
for (long page = startPage; page < endPage; page++)
{
int pageIndex = hlog.GetPageIndexForPage(page);
if (recoveryStatus.flushStatus[pageIndex] == FlushStatus.Pending)
{
done = false;
break;
}
}
}
recoveryStatus.recoveryDevice.Close();
recoveryStatus.objectLogRecoveryDevice.Close();
}