net/disk_cache/blockfile/eviction.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef NET_DISK_CACHE_BLOCKFILE_EVICTION_H_
   6 #define NET_DISK_CACHE_BLOCKFILE_EVICTION_H_
   7
   8 #include "base/basictypes.h"
   9 #include "base/memory/weak_ptr.h"
  10 #include "net/disk_cache/blockfile/rankings.h"
  11
  12 namespace disk_cache {
  13
  14 class BackendImpl;
  15 class EntryImpl;
  16 struct IndexHeader;
  17
  18 // This class implements the eviction algorithm for the cache and it is tightly
  19 // integrated with BackendImpl.
  20 class Eviction {
  21  public:
  22   Eviction();
  23   ~Eviction();
  24
  25   void Init(BackendImpl* backend);
  26   void Stop();
  27
  28   // Deletes entries from the cache until the current size is below the limit.
  29   // If empty is true, the whole cache will be trimmed, regardless of being in
  30   // use.
  31   void TrimCache(bool empty);
  32
  33   // Updates the ranking information for an entry.
  34   void UpdateRank(EntryImpl* entry, bool modified);
  35
  36   // Notifications of interesting events for a given entry.
  37   void OnOpenEntry(EntryImpl* entry);
  38   void OnCreateEntry(EntryImpl* entry);
  39   void OnDoomEntry(EntryImpl* entry);
  40   void OnDestroyEntry(EntryImpl* entry);
  41
  42   // Testing interface.
  43   void SetTestMode();
  44   void TrimDeletedList(bool empty);
  45
  46  private:
  47   void PostDelayedTrim();
  48   void DelayedTrim();
  49   bool ShouldTrim();
  50   bool ShouldTrimDeleted();
  51   void ReportTrimTimes(EntryImpl* entry);
  52   Rankings::List GetListForEntry(EntryImpl* entry);
  53   bool EvictEntry(CacheRankingsBlock* node, bool empty, Rankings::List list);
  54
  55   // We'll just keep for a while a separate set of methods that implement the
  56   // new eviction algorithm. This code will replace the original methods when
  57   // finished.
  58   void TrimCacheV2(bool empty);
  59   void UpdateRankV2(EntryImpl* entry, bool modified);
  60   void OnOpenEntryV2(EntryImpl* entry);
  61   void OnCreateEntryV2(EntryImpl* entry);
  62   void OnDoomEntryV2(EntryImpl* entry);
  63   void OnDestroyEntryV2(EntryImpl* entry);
  64   Rankings::List GetListForEntryV2(EntryImpl* entry);
  65   void TrimDeleted(bool empty);
  66   bool RemoveDeletedNode(CacheRankingsBlock* node);
  67
  68   bool NodeIsOldEnough(CacheRankingsBlock* node, int list);
  69   int SelectListByLength(Rankings::ScopedRankingsBlock* next);
  70   void ReportListStats();
  71
  72   BackendImpl* backend_;
  73   Rankings* rankings_;
  74   IndexHeader* header_;
  75   int max_size_;
  76   int trim_delays_;
  77   int index_size_;
  78   bool new_eviction_;
  79   bool first_trim_;
  80   bool trimming_;
  81   bool delay_trim_;
  82   bool init_;
  83   bool test_mode_;
  84   base::WeakPtrFactory<Eviction> ptr_factory_;
  85
  86   DISALLOW_COPY_AND_ASSIGN(Eviction);
  87 };
  88
  89 }  // namespace disk_cache
  90
  91 #endif  // NET_DISK_CACHE_BLOCKFILE_EVICTION_H_