mcs/class/System.Runtime.Caching/System.Runtime.Caching/MemoryCacheContainer.cs

   1 //
   2 // MemoryCacheContainer.cs
   3 //
   4 // Authors:
   5 //      Marek Habersack <mhabersack@novell.com>
   6 //
   7 // Copyright (C) 2010 Novell, Inc. (http://novell.com/)
   8 //
   9 // Permission is hereby granted, free of charge, to any person obtaining
  10 // a copy of this software and associated documentation files (the
  11 // "Software"), to deal in the Software without restriction, including
  12 // without limitation the rights to use, copy, modify, merge, publish,
  13 // distribute, sublicense, and/or sell copies of the Software, and to
  14 // permit persons to whom the Software is furnished to do so, subject to
  15 // the following conditions:
  16 //
  17 // The above copyright notice and this permission notice shall be
  18 // included in all copies or substantial portions of the Software.
  19 //
  20 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  21 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  22 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  23 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  24 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  25 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  26 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  27 //
  28 using System;
  29 using System.Collections;
  30 using System.Collections.Generic;
  31 using System.Collections.Specialized;
  32 using System.Configuration;
  33 using System.Diagnostics;
  34 using System.Reflection;
  35 using System.Runtime.Caching.Configuration;
  36 using System.Threading;
  37
  38 namespace System.Runtime.Caching
  39 {
  40         sealed class MemoryCacheContainer : IDisposable
  41         {
  42                 ReaderWriterLockSlim cache_lock = new ReaderWriterLockSlim ();
  43
  44                 SortedDictionary <string, MemoryCacheEntry> cache;
  45                 MemoryCache owner;
  46                 MemoryCachePerformanceCounters perfCounters;
  47                 MemoryCacheEntryPriorityQueue timedItems;
  48                 Timer expirationTimer;
  49
  50                 public int ID {
  51                         get; private set;
  52                 }
  53
  54                 public long Count {
  55                         get { return (long)cache.Count; }
  56                 }
  57
  58                 public MemoryCacheContainer (MemoryCache owner, int id, MemoryCachePerformanceCounters perfCounters)
  59                 {
  60                         if (owner == null)
  61                                 throw new ArgumentNullException ("owner");
  62
  63                         this.owner = owner;
  64                         this.ID = id;
  65                         this.perfCounters = perfCounters;
  66                         cache = new SortedDictionary <string, MemoryCacheEntry> ();
  67                 }
  68
  69                 bool ExpireIfNeeded (string key, MemoryCacheEntry entry, bool needsLock = true, CacheEntryRemovedReason reason = CacheEntryRemovedReason.Expired)
  70                 {
  71                         bool locked = false;
  72
  73                         try {
  74                                 if (entry.IsExpired) {
  75                                         if (needsLock) {
  76                                                 cache_lock.EnterWriteLock ();
  77                                                 locked = true;
  78                                         }
  79
  80                                         cache.Remove (key);
  81                                         perfCounters.Decrement (MemoryCachePerformanceCounters.CACHE_ENTRIES);
  82                                         entry.Removed (owner, CacheEntryRemovedReason.Expired);
  83
  84                                         return true;
  85                                 }
  86                         } finally {
  87                                 if (locked)
  88                                         cache_lock.ExitWriteLock ();
  89                         }
  90
  91                         return false;
  92                 }
  93
  94                 public void Dispose ()
  95                 {
  96                         if (expirationTimer != null) {
  97                                 expirationTimer.Dispose ();
  98                                 expirationTimer = null;
  99                         }
 100                 }
 101
 102                 public void CopyEntries (IDictionary dict)
 103                 {
 104                         bool locked = false;
 105                         try {
 106                                 cache_lock.EnterWriteLock ();
 107                                 locked = true;
 108
 109                                 MemoryCacheEntry entry;
 110                                 foreach (var de in cache) {
 111                                         entry = de.Value;
 112
 113                                         if (entry.IsExpired)
 114                                                 continue;
 115
 116                                         dict.Add (de.Key, entry.Value);
 117                                 }
 118                         } finally {
 119                                 if (locked)
 120                                         cache_lock.ExitWriteLock ();
 121                         }
 122                 }
 123
 124                 public bool ContainsKey (string key)
 125                 {
 126                         bool readLocked = false;
 127                         try {
 128                                 cache_lock.EnterUpgradeableReadLock ();
 129                                 readLocked = true;
 130
 131                                 MemoryCacheEntry entry;
 132                                 if (cache.TryGetValue (key, out entry)) {
 133                                         if (ExpireIfNeeded (key, entry))
 134                                                 return false;
 135
 136                                         return true;
 137                                 }
 138
 139                                 return false;
 140                         } finally {
 141                                 if (readLocked)
 142                                         cache_lock.ExitUpgradeableReadLock ();
 143                         }
 144                 }
 145
 146                 // NOTE: this method _MUST_ be called with the write lock held
 147                 void AddToCache (string key, MemoryCacheEntry entry, bool update = false)
 148                 {
 149                         if (update)
 150                                 cache [key] = entry;
 151                         else
 152                                 cache.Add (key, entry);
 153                         entry.Added ();
 154                         if (!update)
 155                                 perfCounters.Increment (MemoryCachePerformanceCounters.CACHE_ENTRIES);
 156
 157                         if (entry.IsExpirable)
 158                                 UpdateExpirable (entry);
 159                 }
 160
 161                 // NOTE: this method _MUST_ be called with the write lock held
 162                 void UpdateExpirable (MemoryCacheEntry entry)
 163                 {
 164                         if (timedItems == null)
 165                                 timedItems = new MemoryCacheEntryPriorityQueue ();
 166
 167                         timedItems.Enqueue (entry);
 168
 169                         if (expirationTimer == null)
 170                                 expirationTimer = new Timer (RemoveExpiredItems, null, owner.TimerPeriod, owner.TimerPeriod);
 171                 }
 172
 173                 void RemoveExpiredItems (object state)
 174                 {
 175                         DoRemoveExpiredItems (true);
 176                 }
 177
 178                 long DoRemoveExpiredItems (bool needLock)
 179                 {
 180                         long count = 0;
 181                         bool locked = false;
 182                         try {
 183                                 if (needLock) {
 184                                         cache_lock.EnterWriteLock ();
 185                                         locked = true;
 186                                 }
 187
 188                                 if (timedItems == null)
 189                                         return 0;
 190
 191                                 long now = DateTime.Now.Ticks;
 192                                 MemoryCacheEntry entry = timedItems.Peek ();
 193
 194                                 while (entry != null) {
 195                                         if (entry.Disabled) {
 196                                                 timedItems.Dequeue ();
 197                                                 entry = timedItems.Peek ();
 198                                                 continue;
 199                                         }
 200
 201                                         if (entry.ExpiresAt > now)
 202                                                 break;
 203
 204                                         timedItems.Dequeue ();
 205                                         count++;
 206                                         DoRemoveEntry (entry, entry.Key, CacheEntryRemovedReason.Expired);
 207                                         entry = timedItems.Peek ();
 208                                 }
 209
 210                                 if (entry == null) {
 211                                         timedItems = null;
 212                                         expirationTimer.Dispose ();
 213                                         expirationTimer = null;
 214                                 }
 215
 216                                 return count;
 217                         } finally {
 218                                 if (locked)
 219                                         cache_lock.ExitWriteLock ();
 220                         }
 221                 }
 222
 223                 public object AddOrGetExisting (string key, object value, CacheItemPolicy policy)
 224                 {
 225                         bool readLocked = false, writeLocked = false;
 226                         try {
 227                                 cache_lock.EnterUpgradeableReadLock ();
 228                                 readLocked = true;
 229
 230                                 MemoryCacheEntry entry;
 231                                 if (cache.TryGetValue (key, out entry) && entry != null) {
 232                                         perfCounters.Increment (MemoryCachePerformanceCounters.CACHE_HITS);
 233                                         return entry.Value;
 234                                 }
 235                                 perfCounters.Increment (MemoryCachePerformanceCounters.CACHE_MISSES);
 236
 237                                 cache_lock.EnterWriteLock ();
 238                                 writeLocked = true;
 239
 240                                 if (policy == null)
 241                                         entry = new MemoryCacheEntry (owner, key, value);
 242                                 else
 243                                         entry = new MemoryCacheEntry (owner, key, value,
 244                                                                       policy.AbsoluteExpiration,
 245                                                                       policy.ChangeMonitors,
 246                                                                       policy.Priority,
 247                                                                       policy.RemovedCallback,
 248                                                                       policy.SlidingExpiration,
 249                                                                       policy.UpdateCallback);
 250
 251                                 AddToCache (key, entry);
 252                                 return null;
 253                         } finally {
 254                                 if (writeLocked)
 255                                         cache_lock.ExitWriteLock ();
 256                                 if (readLocked)
 257                                         cache_lock.ExitUpgradeableReadLock ();
 258                         }
 259                 }
 260
 261                 public MemoryCacheEntry GetEntry (string key)
 262                 {
 263                         bool locked = false;
 264                         try {
 265                                 cache_lock.EnterReadLock ();
 266                                 locked = true;
 267
 268                                 MemoryCacheEntry entry;
 269                                 if (cache.TryGetValue (key, out entry)) {
 270                                         if (ExpireIfNeeded (key, entry))
 271                                                 return null;
 272
 273                                         return entry;
 274                                 }
 275
 276                                 return null;
 277                         } finally {
 278                                 if (locked)
 279                                         cache_lock.ExitReadLock ();
 280                         }
 281                 }
 282
 283                 public object Get (string key)
 284                 {
 285                         bool readLocked = false;
 286                         try {
 287                                 cache_lock.EnterUpgradeableReadLock ();
 288                                 readLocked = true;
 289
 290                                 MemoryCacheEntry entry;
 291                                 if (cache.TryGetValue (key, out entry)) {
 292                                         if (ExpireIfNeeded (key, entry))
 293                                                 return null;
 294
 295                                         perfCounters.Increment (MemoryCachePerformanceCounters.CACHE_HITS);
 296                                         return entry.Value;
 297                                 }
 298
 299                                 perfCounters.Increment (MemoryCachePerformanceCounters.CACHE_MISSES);
 300                                 return null;
 301                         } finally {
 302                                 if (readLocked)
 303                                         cache_lock.ExitUpgradeableReadLock ();
 304                         }
 305                 }
 306
 307                 public object Remove (string key)
 308                 {
 309                         bool writeLocked = false, readLocked = false;
 310                         try {
 311                                 cache_lock.EnterUpgradeableReadLock ();
 312                                 readLocked = true;
 313
 314                                 MemoryCacheEntry entry;
 315                                 if (!cache.TryGetValue (key, out entry))
 316                                         return null;
 317
 318                                 cache_lock.EnterWriteLock ();
 319                                 writeLocked = true;
 320                                 object ret = entry.Value;
 321                                 DoRemoveEntry (entry, key);
 322                                 return ret;
 323                         } finally {
 324                                 if (writeLocked)
 325                                         cache_lock.ExitWriteLock ();
 326                                 if (readLocked)
 327                                         cache_lock.ExitUpgradeableReadLock ();
 328                         }
 329                 }
 330
 331                 // NOTE: this must be called with the write lock held
 332                 void DoRemoveEntry (MemoryCacheEntry entry, string key = null, CacheEntryRemovedReason reason = CacheEntryRemovedReason.Removed)
 333                 {
 334                         if (key == null)
 335                                 key = entry.Key;
 336
 337                         cache.Remove (key);
 338                         perfCounters.Decrement (MemoryCachePerformanceCounters.CACHE_ENTRIES);
 339                         entry.Removed (owner, reason);
 340                 }
 341
 342                 public void Set (string key, object value, CacheItemPolicy policy)
 343                 {
 344                         bool locked = false;
 345                         try {
 346                                 cache_lock.EnterWriteLock ();
 347                                 locked = true;
 348
 349                                 MemoryCacheEntry mce;
 350                                 bool update = false;
 351                                 if (cache.TryGetValue (key, out mce)) {
 352                                         if (mce != null) {
 353                                                 perfCounters.Increment (MemoryCachePerformanceCounters.CACHE_HITS);
 354                                                 mce.Value = value;
 355                                                 mce.SetPolicy (policy);
 356                                                 if (mce.IsExpirable)
 357                                                         UpdateExpirable (mce);
 358                                                 return;
 359                                         }
 360
 361                                         update = true;
 362                                 }
 363                                 perfCounters.Increment (MemoryCachePerformanceCounters.CACHE_MISSES);
 364                                 if (policy != null)
 365                                         mce = new MemoryCacheEntry (owner, key, value,
 366                                                                     policy.AbsoluteExpiration,
 367                                                                     policy.ChangeMonitors,
 368                                                                     policy.Priority,
 369                                                                     policy.RemovedCallback,
 370                                                                     policy.SlidingExpiration,
 371                                                                     policy.UpdateCallback);
 372                                 else
 373                                         mce = new MemoryCacheEntry (owner, key, value);
 374                                 AddToCache (key, mce, update);
 375                         } finally {
 376                                 if (locked)
 377                                         cache_lock.ExitWriteLock ();
 378                         }
 379                 }
 380
 381                 public long Trim (int percent)
 382                 {
 383                         int count = cache.Count;
 384                         if (count == 0)
 385                                 return 0;
 386
 387                         long goal = (long)((count * percent) / 100);
 388                         bool locked = false;
 389                         long ret = 0;
 390
 391                         try {
 392                                 cache_lock.EnterWriteLock ();
 393                                 locked = true;
 394                                 ret = DoRemoveExpiredItems (false);
 395
 396                                 goal -= ret;
 397                                 if (goal > 0) {
 398                                         // TODO: perform LRU removal
 399                         }
 400                         } finally {
 401                                 if (locked)
 402                                         cache_lock.ExitWriteLock ();
 403                         }
 404
 405                         return ret;
 406                 }
 407         }
 408 }