1 /* 2 * Copyright 2013 Google Inc. 3 * 4 * Use of this source code is governed by a BSD-style license that can be 5 * found in the LICENSE file. 6 */ 7 8 #ifndef SkLruImageCache_DEFINED 9 #define SkLruImageCache_DEFINED 10 11 #include "SkImageCache.h" 12 #include "SkThread.h" 13 #include "SkTInternalLList.h" 14 15 class CachedPixels; 16 17 /** 18 * SkImageCache implementation that uses an LRU cache to age out old images. 19 */ 20 class SkLruImageCache : public SkImageCache { 21 22 public: 23 SK_DECLARE_INST_COUNT(SkLruImageCache) 24 25 SkLruImageCache(size_t budget); 26 27 virtual ~SkLruImageCache(); 28 29 #ifdef SK_DEBUG 30 virtual MemoryStatus getMemoryStatus(ID) const SK_OVERRIDE; 31 virtual void purgeAllUnpinnedCaches() SK_OVERRIDE; 32 #endif 33 34 /** 35 * Set the byte limit on cached pixels. If more bytes are used than this, the cache will free 36 * unpinned memory until under the new limit or until all unpinned memory is freed. This will 37 * never free pinned memory, so the cache can potentially remain over the limit. The limit is 38 * enforced each time memory is allocated or released. 39 * 0 is a special flag for an infinite budget. 40 * @return size_t The previous limit. 41 */ 42 size_t setImageCacheLimit(size_t newLimit); 43 44 /** 45 * Return the number of bytes of memory currently in use by the cache. Can include memory that 46 * is no longer pinned, but has not been freed. 47 */ 48 size_t getImageCacheUsed() const { return fRamUsed; } 49 50 virtual void* allocAndPinCache(size_t bytes, ID*) SK_OVERRIDE; 51 virtual void* pinCache(ID, SkImageCache::DataStatus*) SK_OVERRIDE; 52 virtual void releaseCache(ID) SK_OVERRIDE; 53 virtual void throwAwayCache(ID) SK_OVERRIDE; 54 55 private: 56 // Linked list of recently used. Head is the most recently used, and tail is the least. 57 SkTInternalLList<CachedPixels> fLRU; 58 typedef SkTInternalLList<CachedPixels>::Iter Iter; 59 60 #ifdef SK_DEBUG 61 // fMutex is mutable so that getMemoryStatus can be const 62 mutable 63 #endif 64 SkMutex fMutex; 65 size_t fRamBudget; 66 size_t fRamUsed; 67 68 /** 69 * Find the CachedPixels represented by ID, or NULL if not in the cache. Mutex must be locked 70 * before calling. 71 */ 72 CachedPixels* findByID(ID) const; 73 74 /** 75 * If over budget, throw away pixels which are not currently in use until below budget or there 76 * are no more pixels eligible to be thrown away. Mutex must be locked before calling. 77 */ 78 void purgeIfNeeded(); 79 80 /** 81 * Purge until below limit. Mutex must be locked before calling. 82 */ 83 void purgeTilAtOrBelow(size_t limit); 84 85 /** 86 * Remove a set of CachedPixels. Mutex must be locked before calling. 87 */ 88 void removePixels(CachedPixels*); 89 }; 90 91 #endif // SkLruImageCache_DEFINED 92
