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// See net/disk_cache/disk_cache.h for the public interface of the cache. 6 7#ifndef NET_DISK_CACHE_MEMORY_MEM_BACKEND_IMPL_H_ 8#define NET_DISK_CACHE_MEMORY_MEM_BACKEND_IMPL_H_ 9 10#include "base/compiler_specific.h" 11#include "base/containers/hash_tables.h" 12#include "base/memory/weak_ptr.h" 13#include "net/disk_cache/disk_cache.h" 14#include "net/disk_cache/memory/mem_rankings.h" 15 16namespace net { 17class NetLog; 18} // namespace net 19 20namespace disk_cache { 21 22class MemEntryImpl; 23 24// This class implements the Backend interface. An object of this class handles 25// the operations of the cache without writing to disk. 26class NET_EXPORT_PRIVATE MemBackendImpl : public Backend { 27 public: 28 explicit MemBackendImpl(net::NetLog* net_log); 29 virtual ~MemBackendImpl(); 30 31 // Returns an instance of a Backend implemented only in memory. The returned 32 // object should be deleted when not needed anymore. max_bytes is the maximum 33 // size the cache can grow to. If zero is passed in as max_bytes, the cache 34 // will determine the value to use based on the available memory. The returned 35 // pointer can be NULL if a fatal error is found. 36 static scoped_ptr<Backend> CreateBackend(int max_bytes, net::NetLog* net_log); 37 38 // Performs general initialization for this current instance of the cache. 39 bool Init(); 40 41 // Sets the maximum size for the total amount of data stored by this instance. 42 bool SetMaxSize(int max_bytes); 43 44 // Permanently deletes an entry. 45 void InternalDoomEntry(MemEntryImpl* entry); 46 47 // Updates the ranking information for an entry. 48 void UpdateRank(MemEntryImpl* node); 49 50 // A user data block is being created, extended or truncated. 51 void ModifyStorageSize(int32 old_size, int32 new_size); 52 53 // Returns the maximum size for a file to reside on the cache. 54 int MaxFileSize() const; 55 56 // Insert an MemEntryImpl into the ranking list. This method is only called 57 // from MemEntryImpl to insert child entries. The reference can be removed 58 // by calling RemoveFromRankingList(|entry|). 59 void InsertIntoRankingList(MemEntryImpl* entry); 60 61 // Remove |entry| from ranking list. This method is only called from 62 // MemEntryImpl to remove a child entry from the ranking list. 63 void RemoveFromRankingList(MemEntryImpl* entry); 64 65 // Backend interface. 66 virtual net::CacheType GetCacheType() const OVERRIDE; 67 virtual int32 GetEntryCount() const OVERRIDE; 68 virtual int OpenEntry(const std::string& key, Entry** entry, 69 const CompletionCallback& callback) OVERRIDE; 70 virtual int CreateEntry(const std::string& key, Entry** entry, 71 const CompletionCallback& callback) OVERRIDE; 72 virtual int DoomEntry(const std::string& key, 73 const CompletionCallback& callback) OVERRIDE; 74 virtual int DoomAllEntries(const CompletionCallback& callback) OVERRIDE; 75 virtual int DoomEntriesBetween(base::Time initial_time, 76 base::Time end_time, 77 const CompletionCallback& callback) OVERRIDE; 78 virtual int DoomEntriesSince(base::Time initial_time, 79 const CompletionCallback& callback) OVERRIDE; 80 virtual scoped_ptr<Iterator> CreateIterator() OVERRIDE; 81 virtual void GetStats( 82 std::vector<std::pair<std::string, std::string> >* stats) OVERRIDE {} 83 virtual void OnExternalCacheHit(const std::string& key) OVERRIDE; 84 85 private: 86 class MemIterator; 87 friend class MemIterator; 88 89 typedef base::hash_map<std::string, MemEntryImpl*> EntryMap; 90 91 // Old Backend interface. 92 bool OpenEntry(const std::string& key, Entry** entry); 93 bool CreateEntry(const std::string& key, Entry** entry); 94 bool DoomEntry(const std::string& key); 95 bool DoomAllEntries(); 96 bool DoomEntriesBetween(const base::Time initial_time, 97 const base::Time end_time); 98 bool DoomEntriesSince(const base::Time initial_time); 99 100 // Deletes entries from the cache until the current size is below the limit. 101 // If empty is true, the whole cache will be trimmed, regardless of being in 102 // use. 103 void TrimCache(bool empty); 104 105 // Handles the used storage count. 106 void AddStorageSize(int32 bytes); 107 void SubstractStorageSize(int32 bytes); 108 109 EntryMap entries_; 110 MemRankings rankings_; // Rankings to be able to trim the cache. 111 int32 max_size_; // Maximum data size for this instance. 112 int32 current_size_; 113 114 net::NetLog* net_log_; 115 116 base::WeakPtrFactory<MemBackendImpl> weak_factory_; 117 118 DISALLOW_COPY_AND_ASSIGN(MemBackendImpl); 119}; 120 121} // namespace disk_cache 122 123#endif // NET_DISK_CACHE_MEMORY_MEM_BACKEND_IMPL_H_ 124