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/**
* @file lldiskcache.h
* @brief The disk cache implementation.
*
* $LicenseInfo:firstyear=2009&license=viewerlgpl$
* Second Life Viewer Source Code
* Copyright (C) 2020, Linden Research, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation;
* version 2.1 of the License only.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
* Linden Research, Inc., 945 Battery Street, San Francisco, CA 94111 USA
* $/LicenseInfo$
*/
#ifndef _LLDISKCACHE
#define _LLDISKCACHE
class LLDiskCache
{
public:
LLDiskCache(const std::string cache_dir);
~LLDiskCache();
/**
* Update the "last write time" of a file to "now". This must be called whenever a
* file in the cache is read (not written) so that the last time the file was
* accessed which is used in the mechanism for purging the cache, is up to date.
*/
void updateFileAccessTime(const std::string file_path);
/**
* Purge the oldest items in the cache so that the combined size of all files
* is no bigger than mMaxSizeBytes.
*/
void purge();
/**
* Clear the cache by removing the files in the cache directory individually
*/
void clearCache(const std::string cache_dir);
/**
* Manage max size in bytes of cache - use a discrete setter/getter so the value can
* be changed in the preferences and cache cleared/purged without restarting viewer
* to instantiate this class again.
*/
void setMaxSizeBytes(const uintmax_t size_bytes) { mMaxSizeBytes = size_bytes; }
uintmax_t getMaxSizeBytes() const { return mMaxSizeBytes; }
private:
/**
* Utility function to gather the total size the files in a given
* directory. Primarily used here to determine the directory size
* before and after the cache purge
*/
uintmax_t dirFileSize(const std::string dir);
private:
/**
* Default of 20MB seems reasonable - it will likely be reset
* immediately anyway using a value from the Viewer settings
*/
const uintmax_t mDefaultSizeBytes = 20 * 1024 * 1024;
uintmax_t mMaxSizeBytes;
/**
* The folder that holds the cached files. The consumer of this
* class must avoid letting the user set this location as a malicious
* setting could potentially point it at a non-cache directory (for example,
* the Windows System dir) with disastrous results.
*/
std::string mCacheDir;
/**
* This is set from the CacheDebugInfo global setting and
* when enabled, displays additional debugging information in
* various parts of the code
*/
bool mCacheDebugInfo;
};
#endif // _LLDISKCACHE
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