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/*
* Copyright 2013 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef SkLruImageCache_DEFINED
#define SkLruImageCache_DEFINED
#include "SkImageCache.h"
#include "SkThread.h"
#include "SkTInternalLList.h"
class CachedPixels;
/**
* SkImageCache implementation that uses an LRU cache to age out old images.
*/
class SkLruImageCache : public SkImageCache {
public:
SK_DECLARE_INST_COUNT(SkLruImageCache)
SkLruImageCache(size_t budget);
virtual ~SkLruImageCache();
#ifdef SK_DEBUG
virtual MemoryStatus getMemoryStatus(ID) const SK_OVERRIDE;
virtual void purgeAllUnpinnedCaches() SK_OVERRIDE;
#endif
/**
* Set the byte limit on cached pixels. If more bytes are used than this, the cache will free
* unpinned memory until under the new limit or until all unpinned memory is freed. This will
* never free pinned memory, so the cache can potentially remain over the limit. The limit is
* enforced each time memory is allocated or released.
* 0 is a special flag for an infinite budget.
* @return size_t The previous limit.
*/
size_t setImageCacheLimit(size_t newLimit);
/**
* Return the number of bytes of memory currently in use by the cache. Can include memory that
* is no longer pinned, but has not been freed.
*/
size_t getImageCacheUsed() const { return fRamUsed; }
virtual void* allocAndPinCache(size_t bytes, ID*) SK_OVERRIDE;
virtual void* pinCache(ID, SkImageCache::DataStatus*) SK_OVERRIDE;
virtual void releaseCache(ID) SK_OVERRIDE;
virtual void throwAwayCache(ID) SK_OVERRIDE;
private:
// Linked list of recently used. Head is the most recently used, and tail is the least.
SkTInternalLList<CachedPixels> fLRU;
typedef SkTInternalLList<CachedPixels>::Iter Iter;
#ifdef SK_DEBUG
// fMutex is mutable so that getMemoryStatus can be const
mutable
#endif
SkMutex fMutex;
size_t fRamBudget;
size_t fRamUsed;
/**
* Find the CachedPixels represented by ID, or NULL if not in the cache. Mutex must be locked
* before calling.
*/
CachedPixels* findByID(ID) const;
/**
* If over budget, throw away pixels which are not currently in use until below budget or there
* are no more pixels eligible to be thrown away. Mutex must be locked before calling.
*/
void purgeIfNeeded();
/**
* Purge until below limit. Mutex must be locked before calling.
*/
void purgeTilAtOrBelow(size_t limit);
/**
* Remove a set of CachedPixels. Mutex must be locked before calling.
*/
void removePixels(CachedPixels*);
};
#endif // SkLruImageCache_DEFINED
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