2004-05-27 Patrik Torstensson <totte@hiddenpeaks.com>

	* CacheEntry.cs,CacheExpires.cs,ExpiresBucket.cs,
	  Cache.cs : Fixed deadlock issues, fixed
	  items not correctly being flushed, fixed update
	  of item when expiration has been updated more
	  than 1 min (placed in wrong bucket),
	  fixed deadlock during cache callback when item
	  is removed due to expiriation.

	  Rewrite of locking handling in Cache class, leading
	  to better performance and less bugs.

	  This rewrite is due to a number of bugs found
	  in the output caching during load (leading to memory
	  leaks and deadlocks)

svn path=/trunk/mcs/; revision=28254

1 files changed, 56 insertions, 83 deletions

diff --git a/mcs/class/System.Web/System.Web.Caching/CacheExpires.cs b/mcs/class/System.Web/System.Web.Caching/CacheExpires.cs
index 639be6efa99..bdc4748a5a8 100644
--- a/mcs/class/System.Web/System.Web.Caching/CacheExpires.cs
+++ b/mcs/class/System.Web/System.Web.Caching/CacheExpires.cs
@@ -2,22 +2,22 @@
 // System.Web.Caching

 //

 // Author:

-//   Patrik Torstensson (Patrik.Torstensson@labs2.com)

-// Changes:

-//   Daniel Cazzulino [DHC] (dcazzulino@users.sf.net)

+//   Patrik Torstensson

+//   Daniel Cazzulino (dcazzulino@users.sf.net)

 //

-// (C) Copyright Patrik Torstensson, 2001

-//

-namespace System.Web.Caching

-{

+

+using System;

+using System.Collections;

+using System.Threading;

+

+namespace System.Web.Caching {

 	/// <summary>

 	/// Class responsible for handling time based flushing of entries in the cache. The class creates

 	/// and manages 60 buckets each holding every item that expires that minute. The bucket calculated

 	/// for an entry is one minute more than the timeout just to make sure that the item end up in the

 	/// bucket where it should be flushed.

 	/// </summary>

-	internal class CacheExpires : System.IDisposable

-	{

+	internal class CacheExpires : IDisposable {

 		static int	_intFlush;

 		/// <summary>

 		/// 1 bucket == 1 minute == 10M ticks (1 second) * 60

@@ -29,101 +29,79 @@ namespace System.Web.Caching
 		static long _ticksPerCycle = _ticksPerBucket * 60;

 

 		private ExpiresBucket[] _arrBuckets;

-		private System.Threading.Timer _objTimer;

+		private Timer _objTimer;

 		private Cache _objManager;

 

-		/// <summary>

-		/// Constructor

-		/// </summary>

-		/// <param name="objManager">The cache manager, used when flushing items in a bucket.</param>

-		internal CacheExpires(Cache objManager)

-		{

+		private object _lockObj = new object ();

+

+		internal CacheExpires (Cache objManager) {

 			_objManager = objManager;

 			Initialize();

 		}

 

-		/// <summary>

-		/// Initializes the class.

-		/// </summary>

-		private void Initialize()

-		{

+		private void Initialize () {

 			// Create one bucket per minute

-			_arrBuckets = new ExpiresBucket[60];

+			_arrBuckets = new ExpiresBucket [60];

 

 			byte bytePos = 0;

-			do 

-			{

-				_arrBuckets[bytePos] = new ExpiresBucket(bytePos, _objManager);

+			do {

+				_arrBuckets [bytePos] = new ExpiresBucket (bytePos, _objManager);

 				bytePos++;

 			} while (bytePos < 60);

 

 			// GC Bucket controller

 			_intFlush = System.DateTime.Now.Minute - 1;

-			_objTimer = new System.Threading.Timer(new System.Threading.TimerCallback(GarbageCleanup), null, 10000, 60000);

+			_objTimer = new System.Threading.Timer (new System.Threading.TimerCallback (GarbageCleanup), null, 10000, 60000);

 		}

 

 		/// <summary>

 		/// Adds a Cache entry to the correct flush bucket.

 		/// </summary>

 		/// <param name="objEntry">Cache entry to add.</param>

-		internal void Add (CacheEntry objEntry)

-		{

-			lock(this) 

-			{

-				// If the entry doesn't have a expires time we assume that the entry is due to expire now.

-				if (objEntry.Expires == 0) 

-				{

-					objEntry.Expires = System.DateTime.Now.Ticks;

-				}

-

-                _arrBuckets[GetHashBucket(objEntry.Expires)].Add(objEntry);

-			}

+		internal void Add (CacheEntry objEntry) {

+			long now = DateTime.Now.Ticks;

+			if (objEntry.Expires < now)

+				objEntry.Expires = now;

+

+			_arrBuckets [GetHashBucket (objEntry.Expires)].Add (objEntry);

 		}

 

-		internal void Remove(CacheEntry objEntry)

-		{

-			lock(this) 

-			{

-				// If the entry doesn't have a expires time we assume that the entry is due to expire now.

-				if (objEntry.Expires == 0) 

-				{

-					objEntry.Expires = System.DateTime.Now.Ticks;

-				}

-

-				_arrBuckets[GetHashBucket(objEntry.Expires)].Remove(objEntry);

-			}

+		internal void Remove (CacheEntry objEntry) {

+			if (objEntry.ExpiresBucket != CacheEntry.NoBucketHash)

+				_arrBuckets [objEntry.ExpiresBucket].Remove (objEntry);

 		}

 

-		internal void Update(CacheEntry objEntry, long ticksExpires)

-		{

-			lock(this) 

-			{

-				// If the entry doesn't have a expires time we assume that the entry is due to expire now.

-				if (objEntry.Expires == 0) 

-				{

-					objEntry.Expires = System.DateTime.Now.Ticks;

-				}

-

-				_arrBuckets[GetHashBucket(objEntry.Expires)].Update(objEntry, ticksExpires);

-			}		

+		internal void Update (CacheEntry objEntry, long ticksExpires) {

+			// If the entry doesn't have a expires time we assume that the entry is due to expire now.

+			int oldBucket = objEntry.ExpiresBucket;

+			int newBucket = GetHashBucket (ticksExpires);

+

+			if (oldBucket == CacheEntry.NoBucketHash)

+				return;

+

+			// Check if we need to move the item

+			if (oldBucket != newBucket) {

+				_arrBuckets [oldBucket].Remove (objEntry);

+				objEntry.Expires = ticksExpires;

+				_arrBuckets [newBucket].Add (objEntry);

+			} else

+				_arrBuckets [oldBucket].Update (objEntry, ticksExpires);

 		}

 

-		internal void GarbageCleanup(object State)

-		{

-			ExpiresBucket	objBucket;

+		internal void GarbageCleanup (object State) {

+			ExpiresBucket objBucket;

+			int bucket;

 

-			lock(this)

-			{

-				// Do cleanup of the bucket 

-				objBucket = _arrBuckets[(++_intFlush) % 60];

-			}	

+			// We lock here if FlushExpiredItems take time

+			lock (_lockObj) {

+				bucket = (++_intFlush) % 60;

+			}

 

 			// Flush expired items in the current bucket (defined by _intFlush)

-			objBucket.FlushExpiredItems();

+			_arrBuckets [bucket].FlushExpiredItems ();

 		}

 

-		private int GetHashBucket(long ticks)

-		{

+		private int GetHashBucket (long ticks) {

 			// Get bucket to add expire item into, add one minute to the bucket just to make sure that we get it in the bucket gc

 			return (int) (((((ticks + 60000) % _ticksPerCycle) / _ticksPerBucket) + 1) % 60);

 		}

@@ -131,16 +109,11 @@ namespace System.Web.Caching
 		/// <summary>

 		/// Called by the cache for cleanup.

 		/// </summary>

-		public void Dispose()

-		{

-			lock(this)

-			{

-				// Cleanup the internal timer

-				if (_objTimer != null)

-				{

-					_objTimer.Dispose();

-					_objTimer = null;

-				}

+		public void Dispose () {

+			// Cleanup the internal timer

+			if (_objTimer != null) {

+				_objTimer.Dispose();

+				_objTimer = null;

 			}

 		}

 	}