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// Copyright 2008, Google Inc.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
// 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 <hash_map>
#include "net/disk_cache/disk_cache.h"
#include "net/disk_cache/mem_rankings.h"
namespace disk_cache {
class MemEntryImpl;
// This class implements the Backend interface. An object of this class handles
// the operations of the cache without writting to disk.
class MemBackendImpl : public Backend {
public:
MemBackendImpl() : max_size_(0), current_size_(0) {}
~MemBackendImpl();
// Performs general initialization for this current instance of the cache.
bool Init();
// Backend interface.
virtual int32 GetEntryCount() const;
virtual bool OpenEntry(const std::string& key, Entry** entry);
virtual bool CreateEntry(const std::string& key, Entry** entry);
virtual bool DoomEntry(const std::string& key);
virtual bool DoomAllEntries();
virtual bool DoomEntriesBetween(const Time initial_time, const Time end_time);
virtual bool DoomEntriesSince(const Time initial_time);
virtual bool OpenNextEntry(void** iter, Entry** next_entry);
virtual void EndEnumeration(void** iter);
virtual void GetStats(
std::vector<std::pair<std::string, std::string> >* stats) {}
// 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;
private:
// 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);
typedef stdext::hash_map<std::string, MemEntryImpl*> EntryMap;
EntryMap entries_;
MemRankings rankings_; // Rankings to be able to trim the cache.
int32 max_size_; // Maximum data size for this instance.
int32 current_size_;
DISALLOW_EVIL_CONSTRUCTORS(MemBackendImpl);
};
} // namespace disk_cache
#endif // NET_DISK_CACHE_MEM_BACKEND_IMPL_H__
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