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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, t
he cache will free | |
36 * unpinned memory until under the new limit or until all unpinned memory i
s freed. This will | |
37 * never free pinned memory, so the cache can potentially remain over the l
imit. 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. Mu
tex 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 b
elow budget or there | |
76 * are no more pixels eligible to be thrown away. Mutex must be locked befo
re 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 typedef SkImageCache INHERITED; | |
90 }; | |
91 | |
92 #endif // SkLruImageCache_DEFINED | |
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