aria2/src/WrDiskCache.h

80 lines
2.7 KiB
C++

/* <!-- copyright */
/*
* aria2 - The high speed download utility
*
* Copyright (C) 2012 Tatsuhiro Tsujikawa
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
* In addition, as a special exception, the copyright holders give
* permission to link the code of portions of this program with the
* OpenSSL library under certain conditions as described in each
* individual source file, and distribute linked combinations
* including the two.
* You must obey the GNU General Public License in all respects
* for all of the code used other than OpenSSL. If you modify
* file(s) with this exception, you may extend this exception to your
* version of the file(s), but you are not obligated to do so. If you
* do not wish to do so, delete this exception statement from your
* version. If you delete this exception statement from all source
* files in the program, then also delete it here.
*/
/* copyright --> */
#ifndef D_WR_DISK_CACHE_H
#define D_WR_DISK_CACHE_H
#include "common.h"
#include <set>
#include "a2functional.h"
namespace aria2 {
class WrDiskCacheEntry;
class WrDiskCache {
public:
WrDiskCache(size_t limit);
~WrDiskCache();
// Adds the cache entry |ent| to the storage. The size of cached
// data of ent is added to total_.
bool add(WrDiskCacheEntry* ent);
// Removes the cache entry |ent| from the stroage. The size of
// cached data of ent is subtracted from total_.
bool remove(WrDiskCacheEntry* ent);
// Updates the already added entry |ent|. The |delta| means how many
// bytes is increased in this update. If the size is reduced, use
// negative value.
bool update(WrDiskCacheEntry* ent, ssize_t delta);
// Evicts entries from storage so that total size of cache is kept
// under the limit.
void ensureLimit();
size_t getSize() const { return total_; }
private:
typedef std::set<WrDiskCacheEntry*, DerefLess<WrDiskCacheEntry*>> EntrySet;
// Maximum number of bytes the storage can cache.
size_t limit_;
// Current number of bytes cached.
size_t total_;
EntrySet set_;
int64_t clock_;
};
} // namespace aria2
#endif // D_WR_DISK_CACHE_H