/// <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;
}
}
}
}
private void FireAfterEvict(EvictionEventArgs evictionArgs)
{
if (AfterEvict != null)
{
AfterEvict(this, evictionArgs);
}
}
/// <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;
}
}
}
}
private void FirePostEvict(EvictionEventArgs args)
{
if (AfterEvict != null)
{
AfterEvict(this, args);
}
}
private void FireBeforeEvict(EvictionEventArgs evictionArgs)
{
if (BeforeEvict != null)
{
BeforeEvict(this, evictionArgs);
}
}
private void FirePostEvict(EvictionEventArgs args)
{
if (AfterEvict != null)
{
AfterEvict(this, args);
}
}
private bool FirePreEvict(EvictionEventArgs args)
{
if (BeforeEvict != null)
{
BeforeEvict(this, args);
}
return(!args.CancelEviction);
}
private bool FirePreEvict(EvictionEventArgs args)
{
if (BeforeEvict != null)
{
BeforeEvict(this, args);
}
return !args.CancelEviction;
}
private void EvictItems()
{
if (_evictInProgress)
{
return;
}
_evictInProgress = true;
try
{
#if DEBUG_PAGECACHE
Logging.LogDebug("LruPageCache.EvictItems: START");
#endif
var evictPointer = _accessList.Last;
while (evictPointer != null && _count > _lowWaterMark)
{
var partition = evictPointer.Value.Key;
var pageId = evictPointer.Value.Value.Id;
var evictionArgs = new EvictionEventArgs(partition, pageId);
#if DEBUG_PAGECACHE
Logging.LogDebug("LruPageCache.EvictItems: Selected {0}", pageId);
#endif
FireBeforeEvict(evictionArgs);
if (!evictionArgs.CancelEviction)
{
var cacheKey = MakeCacheKey(partition, pageId);
var tmp = evictPointer.Previous;
_accessList.Remove(evictPointer);
_cacheItems.Remove(cacheKey);
_count--;
FireAfterEvict(evictionArgs);
#if DEBUG_PAGECACHE
Logging.LogDebug("LruPageCache.EvictItems: Evicted {0}", pageId);
#endif
evictPointer = tmp;
}
else
{
#if DEBUG_PAGECACHE
Logging.LogDebug("LruPageCache.EvictItems: Eviction of {0} was cancelled", pageId);
#endif
evictPointer = evictPointer.Previous;
}
}
#if DEBUG_PAGECACHE
Logging.LogDebug("LruPageCache.EvictItems: END");
#endif
}
finally
{
_evictInProgress = false;
}
}
private void BeforePageCacheEvict(object sender, EvictionEventArgs args)
{
if (args.Partition.Equals(_filePath))
{
Tuple<BinaryFilePage, ulong> bfpTuple;
if (_modifiedPages.TryGetValue(args.PageId, out bfpTuple))
{
EnsureOutputStream();
bfpTuple.Item1.Write(_outputStream, bfpTuple.Item2);
}
_modifiedPages.Remove(args.PageId);
}
}
public void Clear(string partition)
{
var partitionId = AssertPartitionId(partition);
foreach(var k in _pages.Keys.Where(k=>k.PartitionId == partitionId).ToList())
{
var eventArgs = new EvictionEventArgs(partition, k.PageId);
if (FirePreEvict(eventArgs))
{
_pages.Remove(k);
FirePostEvict(eventArgs);
}
}
}
private void BeforePageCacheEvict(object sender, EvictionEventArgs args)
{
if (args.Partition.Equals(_filePath))
{
Tuple <BinaryFilePage, ulong> bfpTuple;
if (_modifiedPages.TryGetValue(args.PageId, out bfpTuple))
{
EnsureOutputStream();
bfpTuple.Item1.Write(_outputStream, bfpTuple.Item2);
}
_modifiedPages.Remove(args.PageId);
}
}
public void Clear(string partition)
{
var partitionId = AssertPartitionId(partition);
foreach (var k in _pages.Keys.Where(k => k.PartitionId == partitionId).ToList())
{
var eventArgs = new EvictionEventArgs(partition, k.PageId);
if (FirePreEvict(eventArgs))
{
_pages.Remove(k);
FirePostEvict(eventArgs);
}
}
}
private void BeforePageCacheEvict(object sender, EvictionEventArgs args)
{
args.CancelEviction = _modifiedPages.ContainsKey(args.PageId);
return;
/*
* lock (_restartLock) // Ensure we don't try to process page evictions while restarting the background writer
* {
* if (_modifiedPages.ContainsKey(args.PageId))
* {
* var page = PageCache.Instance.Lookup(_filePath, args.PageId) as BinaryFilePage;
* if (page != null)
* {
* _backgroundPageWriter.QueueWrite(page, _currentReadTxnId + 1);
* }
* }
* // Unmodified pages can just be evicted
* }
*/
}
private void EvictItems()
{
if (DateTime.Now.Subtract(_cacheBlocked).TotalSeconds < BlockedCacheRetryTimeout)
{
#if DEBUG_PAGECACHE
Logging.LogDebug("LruPageCache.EvictItems: In cache blocked timeout.");
#endif
return; // Last eviction failed recently so don't repeat until the timeout is exceeded
}
if (_evictInProgress) return;
_evictInProgress = true;
try
{
#if DEBUG_PAGECACHE
Logging.LogDebug("LruPageCache.EvictItems: START");
#endif
var evictionCount = 0;
lock (_updateLock)
{
var evictPointer = _accessList.Last;
while (evictPointer != null && _count > _lowWaterMark)
{
var partition = evictPointer.Value.Key;
var pageId = evictPointer.Value.Value.Id;
var evictionArgs = new EvictionEventArgs(partition, pageId);
#if DEBUG_PAGECACHE
Logging.LogDebug("LruPageCache.EvictItems: Selected {0}", pageId);
#endif
FireBeforeEvict(evictionArgs);
if (!evictionArgs.CancelEviction)
{
var cacheKey = MakeCacheKey(partition, pageId);
var tmp = evictPointer.Previous;
_accessList.Remove(evictPointer);
_cacheItems.Remove(cacheKey);
_count--;
evictionCount++;
FireAfterEvict(evictionArgs);
#if DEBUG_PAGECACHE
Logging.LogDebug("LruPageCache.EvictItems: Evicted {0}", pageId);
#endif
evictPointer = tmp;
}
else
{
#if DEBUG_PAGECACHE
Logging.LogDebug("LruPageCache.EvictItems: Eviction of {0} was cancelled", pageId);
#endif
evictPointer = evictPointer.Previous;
}
}
}
if (evictionCount == 0)
{
// The entire cache is blocked with modified pages that cannot be written out
// this can happen with large transactions on the BinaryFilePageStore or on
// the AppendOnlyFilePageStore with background writes disabled.
// To prevent repeated iteration through a blocked cache we will check this timestamp:
_cacheBlocked = DateTime.Now;
#if DEBUG_PAGECACHE
Logging.LogDebug("LruPageCache.EvictItems: Setting cached blocked timeout");
#endif
}
#if DEBUG_PAGECACHE
Logging.LogDebug("LruPageCache.EvictItems: END");
#endif
}
finally
{
try
{
FireEvictionCompleted();
}
finally
{
_evictInProgress = false;
}
}
}
private void EvictItems()
{
if (DateTime.Now.Subtract(_cacheBlocked).TotalSeconds < BlockedCacheRetryTimeout)
{
#if DEBUG_PAGECACHE
Logging.LogDebug("LruPageCache.EvictItems: In cache blocked timeout.");
#endif
return; // Last eviction failed recently so don't repeat until the timeout is exceeded
}
if (_evictInProgress)
{
return;
}
_evictInProgress = true;
try
{
#if DEBUG_PAGECACHE
Logging.LogDebug("LruPageCache.EvictItems: START");
#endif
var evictionCount = 0;
lock (_updateLock)
{
var evictPointer = _accessList.Last;
while (evictPointer != null && _count > _lowWaterMark)
{
var partition = evictPointer.Value.Key;
var pageId = evictPointer.Value.Value.Id;
var evictionArgs = new EvictionEventArgs(partition, pageId);
#if DEBUG_PAGECACHE
Logging.LogDebug("LruPageCache.EvictItems: Selected {0}", pageId);
#endif
FireBeforeEvict(evictionArgs);
if (!evictionArgs.CancelEviction)
{
var cacheKey = MakeCacheKey(partition, pageId);
var tmp = evictPointer.Previous;
_accessList.Remove(evictPointer);
_cacheItems.Remove(cacheKey);
_count--;
evictionCount++;
FireAfterEvict(evictionArgs);
#if DEBUG_PAGECACHE
Logging.LogDebug("LruPageCache.EvictItems: Evicted {0}", pageId);
#endif
evictPointer = tmp;
}
else
{
#if DEBUG_PAGECACHE
Logging.LogDebug("LruPageCache.EvictItems: Eviction of {0} was cancelled", pageId);
#endif
evictPointer = evictPointer.Previous;
}
}
}
if (evictionCount == 0)
{
// The entire cache is blocked with modified pages that cannot be written out
// this can happen with large transactions on the BinaryFilePageStore or on
// the AppendOnlyFilePageStore with background writes disabled.
// To prevent repeated iteration through a blocked cache we will check this timestamp:
_cacheBlocked = DateTime.Now;
#if DEBUG_PAGECACHE
Logging.LogDebug("LruPageCache.EvictItems: Setting cached blocked timeout");
#endif
}
#if DEBUG_PAGECACHE
Logging.LogDebug("LruPageCache.EvictItems: END");
#endif
}
finally
{
try
{
FireEvictionCompleted();
}
finally
{
_evictInProgress = false;
}
}
}
private void EvictItems()
{
if (_evictInProgress) return;
_evictInProgress = true;
try
{
#if DEBUG_PAGECACHE
Logging.LogDebug("LruPageCache.EvictItems: START");
#endif
var evictPointer = _accessList.Last;
while (evictPointer != null && _count > _lowWaterMark)
{
var partition = evictPointer.Value.Key;
var pageId = evictPointer.Value.Value.Id;
var evictionArgs = new EvictionEventArgs(partition, pageId);
#if DEBUG_PAGECACHE
Logging.LogDebug("LruPageCache.EvictItems: Selected {0}", pageId);
#endif
FireBeforeEvict(evictionArgs);
if (!evictionArgs.CancelEviction)
{
var cacheKey = MakeCacheKey(partition, pageId);
var tmp = evictPointer.Previous;
_accessList.Remove(evictPointer);
_cacheItems.Remove(cacheKey);
_count--;
FireAfterEvict(evictionArgs);
#if DEBUG_PAGECACHE
Logging.LogDebug("LruPageCache.EvictItems: Evicted {0}", pageId);
#endif
evictPointer = tmp;
}
else
{
#if DEBUG_PAGECACHE
Logging.LogDebug("LruPageCache.EvictItems: Eviction of {0} was cancelled", pageId);
#endif
evictPointer = evictPointer.Previous;
}
}
#if DEBUG_PAGECACHE
Logging.LogDebug("LruPageCache.EvictItems: END");
#endif
}
finally
{
_evictInProgress = false;
}
}
private void FireAfterEvict(EvictionEventArgs evictionArgs)
{
if (AfterEvict != null) AfterEvict(this, evictionArgs);
}
private void FireBeforeEvict(EvictionEventArgs evictionArgs)
{
if (BeforeEvict != null) BeforeEvict(this, evictionArgs);
}
private void BeforePageCacheEvict(object sender, EvictionEventArgs args)
{
args.CancelEviction = _modifiedPages.ContainsKey(args.PageId);
return;
/*
lock (_restartLock) // Ensure we don't try to process page evictions while restarting the background writer
{
if (_modifiedPages.ContainsKey(args.PageId))
{
var page = PageCache.Instance.Lookup(_filePath, args.PageId) as BinaryFilePage;
if (page != null)
{
_backgroundPageWriter.QueueWrite(page, _currentReadTxnId + 1);
}
}
// Unmodified pages can just be evicted
}
*/
}