/// <summary>
/// Handles notification of page eviction from the page cache
/// </summary>
/// <param name="sender">The page cache performing the eviction</param>
/// <param name="args">The evication event arguments</param>
/// <remarks>When the eviction event is for a writeable page, this handler
/// ensures that the page is queued with the background page writer. If there
/// is no background page writer because the page store was created with the
/// disableBackgroundWriter option, then this method cancels an eviction
/// for a writeable page.</remarks>
private void BeforePageCacheEvict(object sender, EvictionEventArgs args)
{
if (args.Partition.Equals(_path))
{
// Evicting a page from this store
if (args.PageId >= _newPageOffset)
{
// Evicting a writeable page - add the page to the background write queue to ensure it gets written out.
if (_backgroundPageWriter == null)
{
// Do not evict this page
args.CancelEviction = true;
}
else
{
// Queue the page with the background page writer
#if DEBUG_PAGESTORE
Logging.LogDebug("Evict {0}", args.PageId);
#endif
var pageToEvict = _newPages[(int)(args.PageId - _newPageOffset)];
if (pageToEvict.IsAlive)
{
// Passing 0 for the transaction id is OK because it is not used for writing append-only pages
_backgroundPageWriter.QueueWrite(pageToEvict.Target as IPage, 0ul);
}
// Once the page write is queued, the cache entry can be evicted.
// The background page writer will hold on to the page data object until it is written
args.CancelEviction = false;
}
}
}
}
public void Commit(ulong commitId, BrightstarProfiler profiler)
{
if (CanWrite)
{
foreach (var pageId in _modifiedPages.Keys)
{
var page = PageCache.Instance.Lookup(_partitionId, pageId) as BinaryFilePage;
if (page != null && page.IsDirty)
{
_backgroundPageWriter.QueueWrite(page, commitId);
}
}
_backgroundPageWriter.Flush();
lock (_restartLock)
{
_backgroundPageWriter.Shutdown();
_backgroundPageWriter.Dispose();
PageCache.Instance.Clear(_partitionId);
UpdatePartitionId();
_readTxnId = _writeTxnId;
_writeTxnId++;
_backgroundPageWriter =
new BackgroundPageWriter(_persistenceManager.GetOutputStream(_filePath, FileMode.Open));
}
}
else
{
throw new InvalidOperationException("Attempt to Commit on a read-only store instance");
}
}
public void Commit(ulong commitId, BrightstarProfiler profiler)
{
using (profiler.Step("PageStore.Commit"))
{
if (_backgroundPageWriter != null)
{
foreach (var p in _newPages)
{
_backgroundPageWriter.QueueWrite(p, commitId);
}
_backgroundPageWriter.Flush();
RestartBackgroundWriter();
foreach (var p in _newPages)
{
PageCache.Instance.InsertOrUpdate(_path, p);
}
}
else
{
using (var outputStream = _peristenceManager.GetOutputStream(_path, FileMode.Open))
{
foreach (var p in _newPages)
{
p.Write(outputStream, commitId);
PageCache.Instance.InsertOrUpdate(_path, p);
}
}
}
_newPages.Clear();
_newPageOffset = _nextPageId;
}
/*
* using (var writeStream = _peristenceManager.GetOutputStream(_path, FileMode.Open))
* {
* writeStream.Seek((long) ((_newPageOffset - 1)*(ulong) _pageSize), SeekOrigin.Begin);
* foreach (var p in _newPages)
* {
* writeStream.Write(p.Data, 0, _pageSize);
* }
* writeStream.Flush();
* _newPages.Clear();
* _newPageOffset = _nextPageId;
* }
*/
}
