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//
// System.Web.Caching
//
// Author:
// Patrik Torstensson
// Daniel Cazzulino (dcazzulino@users.sf.net)
//
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
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 : IDisposable {
static int _intFlush;
/// <summary>
/// 1 bucket == 1 minute == 10M ticks (1 second) * 60
/// </summary>
static long _ticksPerBucket = 600000000;
/// <summary>
/// 1 cycle == 1 hour
/// </summary>
static long _ticksPerCycle = _ticksPerBucket * 60;
private ExpiresBucket[] _arrBuckets;
private Timer _objTimer;
private Cache _objManager;
private object _lockObj = new object ();
internal CacheExpires (Cache objManager) {
_objManager = objManager;
Initialize();
}
private void Initialize () {
// Create one bucket per minute
_arrBuckets = new ExpiresBucket [60];
byte bytePos = 0;
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);
}
/// <summary>
/// Adds a Cache entry to the correct flush bucket.
/// </summary>
/// <param name="objEntry">Cache entry to add.</param>
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) {
if (objEntry.ExpiresBucket != CacheEntry.NoBucketHash)
_arrBuckets [objEntry.ExpiresBucket].Remove (objEntry);
}
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;
int bucket;
// We lock here if FlushExpiredItems take time
lock (_lockObj) {
bucket = (++_intFlush) % 60;
}
// Flush expired items in the current bucket (defined by _intFlush)
_arrBuckets [bucket].FlushExpiredItems ();
}
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);
}
/// <summary>
/// Called by the cache for cleanup.
/// </summary>
public void Dispose () {
// Cleanup the internal timer
if (_objTimer != null) {
_objTimer.Dispose();
_objTimer = null;
}
}
}
}
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