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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// See net/disk_cache/disk_cache.h for the public interface of the cache.
#ifndef NET_DISK_CACHE_MEM_BACKEND_IMPL_H__
#define NET_DISK_CACHE_MEM_BACKEND_IMPL_H__
#include "base/compiler_specific.h"
#include "base/hash_tables.h"
#include "net/disk_cache/disk_cache.h"
#include "net/disk_cache/mem_rankings.h"
namespace net {
class NetLog;
} // namespace net
namespace disk_cache {
class MemEntryImpl;
// This class implements the Backend interface. An object of this class handles
// the operations of the cache without writing to disk.
class NET_EXPORT_PRIVATE MemBackendImpl : public Backend {
public:
explicit MemBackendImpl(net::NetLog* net_log);
virtual ~MemBackendImpl();
// Returns an instance of a Backend implemented only in memory. The returned
// object should be deleted when not needed anymore. max_bytes is the maximum
// size the cache can grow to. If zero is passed in as max_bytes, the cache
// will determine the value to use based on the available memory. The returned
// pointer can be NULL if a fatal error is found.
static Backend* CreateBackend(int max_bytes, net::NetLog* net_log);
// Performs general initialization for this current instance of the cache.
bool Init();
// Sets the maximum size for the total amount of data stored by this instance.
bool SetMaxSize(int max_bytes);
// Permanently deletes an entry.
void InternalDoomEntry(MemEntryImpl* entry);
// Updates the ranking information for an entry.
void UpdateRank(MemEntryImpl* node);
// A user data block is being created, extended or truncated.
void ModifyStorageSize(int32 old_size, int32 new_size);
// Returns the maximum size for a file to reside on the cache.
int MaxFileSize() const;
// Insert an MemEntryImpl into the ranking list. This method is only called
// from MemEntryImpl to insert child entries. The reference can be removed
// by calling RemoveFromRankingList(|entry|).
void InsertIntoRankingList(MemEntryImpl* entry);
// Remove |entry| from ranking list. This method is only called from
// MemEntryImpl to remove a child entry from the ranking list.
void RemoveFromRankingList(MemEntryImpl* entry);
// Backend interface.
virtual int32 GetEntryCount() const OVERRIDE;
virtual int OpenEntry(const std::string& key, Entry** entry,
const CompletionCallback& callback) OVERRIDE;
virtual int CreateEntry(const std::string& key, Entry** entry,
const CompletionCallback& callback) OVERRIDE;
virtual int DoomEntry(const std::string& key,
const CompletionCallback& callback) OVERRIDE;
virtual int DoomAllEntries(const CompletionCallback& callback) OVERRIDE;
virtual int DoomEntriesBetween(const base::Time initial_time,
const base::Time end_time,
const CompletionCallback& callback) OVERRIDE;
virtual int DoomEntriesSince(const base::Time initial_time,
const CompletionCallback& callback) OVERRIDE;
virtual int OpenNextEntry(void** iter, Entry** next_entry,
const CompletionCallback& callback) OVERRIDE;
virtual void EndEnumeration(void** iter) OVERRIDE;
virtual void GetStats(
std::vector<std::pair<std::string, std::string> >* stats) OVERRIDE {}
virtual void OnExternalCacheHit(const std::string& key) OVERRIDE;
private:
typedef base::hash_map<std::string, MemEntryImpl*> EntryMap;
// Old Backend interface.
bool OpenEntry(const std::string& key, Entry** entry);
bool CreateEntry(const std::string& key, Entry** entry);
bool DoomEntry(const std::string& key);
bool DoomAllEntries();
bool DoomEntriesBetween(const base::Time initial_time,
const base::Time end_time);
bool DoomEntriesSince(const base::Time initial_time);
bool OpenNextEntry(void** iter, Entry** next_entry);
// Deletes entries from the cache until the current size is below the limit.
// If empty is true, the whole cache will be trimmed, regardless of being in
// use.
void TrimCache(bool empty);
// Handles the used storage count.
void AddStorageSize(int32 bytes);
void SubstractStorageSize(int32 bytes);
EntryMap entries_;
MemRankings rankings_; // Rankings to be able to trim the cache.
int32 max_size_; // Maximum data size for this instance.
int32 current_size_;
net::NetLog* net_log_;
DISALLOW_COPY_AND_ASSIGN(MemBackendImpl);
};
} // namespace disk_cache
#endif // NET_DISK_CACHE_MEM_BACKEND_IMPL_H__
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