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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.
*/
#include "SkLruImageCache.h"
static intptr_t NextGenerationID() {
static intptr_t gNextID;
do {
gNextID++;
} while (SkImageCache::UNINITIALIZED_ID == gNextID);
return gNextID;
}
class CachedPixels : public SkNoncopyable {
public:
CachedPixels(size_t length)
: fLength(length)
, fID(NextGenerationID())
, fLocked(false) {
fAddr = sk_malloc_throw(length);
}
~CachedPixels() {
sk_free(fAddr);
}
void* getData() { return fAddr; }
intptr_t getID() const { return fID; }
size_t getLength() const { return fLength; }
void lock() { SkASSERT(!fLocked); fLocked = true; }
void unlock() { SkASSERT(fLocked); fLocked = false; }
bool isLocked() const { return fLocked; }
private:
void* fAddr;
size_t fLength;
const intptr_t fID;
bool fLocked;
SK_DECLARE_INTERNAL_LLIST_INTERFACE(CachedPixels);
};
////////////////////////////////////////////////////////////////////////////////////
SkLruImageCache::SkLruImageCache(size_t budget)
: fRamBudget(budget)
, fRamUsed(0) {}
SkLruImageCache::~SkLruImageCache() {
// Don't worry about updating pointers. All will be deleted.
Iter iter;
CachedPixels* pixels = iter.init(fLRU, Iter::kTail_IterStart);
while (pixels != NULL) {
CachedPixels* prev = iter.prev();
SkASSERT(!pixels->isLocked());
#ifdef SK_DEBUG
fRamUsed -= pixels->getLength();
#endif
SkDELETE(pixels);
pixels = prev;
}
#ifdef SK_DEBUG
SkASSERT(fRamUsed == 0);
#endif
}
#ifdef SK_DEBUG
SkImageCache::CacheStatus SkLruImageCache::getCacheStatus(intptr_t ID) const {
SkAutoMutexAcquire ac(&fMutex);
CachedPixels* pixels = this->findByID(ID);
if (NULL == pixels) {
return SkImageCache::kThrownAway_CacheStatus;
}
if (pixels->isLocked()) {
return SkImageCache::kPinned_CacheStatus;
}
return SkImageCache::kUnpinned_CacheStatus;
}
#endif
void SkLruImageCache::setBudget(size_t newBudget) {
SkAutoMutexAcquire ac(&fMutex);
fRamBudget = newBudget;
this->purgeIfNeeded();
}
void* SkLruImageCache::allocAndPinCache(size_t bytes, intptr_t* ID) {
SkAutoMutexAcquire ac(&fMutex);
CachedPixels* pixels = SkNEW_ARGS(CachedPixels, (bytes));
if (ID != NULL) {
*ID = pixels->getID();
}
pixels->lock();
fRamUsed += bytes;
fLRU.addToHead(pixels);
this->purgeIfNeeded();
return pixels->getData();
}
void* SkLruImageCache::pinCache(intptr_t ID) {
SkASSERT(ID != SkImageCache::UNINITIALIZED_ID);
SkAutoMutexAcquire ac(&fMutex);
CachedPixels* pixels = this->findByID(ID);
if (NULL == pixels) {
return NULL;
}
if (pixels != fLRU.head()) {
fLRU.remove(pixels);
fLRU.addToHead(pixels);
}
pixels->lock();
return pixels->getData();
}
void SkLruImageCache::releaseCache(intptr_t ID) {
SkASSERT(ID != SkImageCache::UNINITIALIZED_ID);
SkAutoMutexAcquire ac(&fMutex);
CachedPixels* pixels = this->findByID(ID);
SkASSERT(pixels != NULL);
pixels->unlock();
this->purgeIfNeeded();
}
void SkLruImageCache::throwAwayCache(intptr_t ID) {
SkASSERT(ID != SkImageCache::UNINITIALIZED_ID);
SkAutoMutexAcquire ac(&fMutex);
CachedPixels* pixels = this->findByID(ID);
if (pixels != NULL) {
if (pixels->isLocked()) {
pixels->unlock();
}
this->removePixels(pixels);
}
}
void SkLruImageCache::removePixels(CachedPixels* pixels) {
// Mutex is already locked.
SkASSERT(!pixels->isLocked());
const size_t size = pixels->getLength();
SkASSERT(size <= fRamUsed);
fLRU.remove(pixels);
SkDELETE(pixels);
fRamUsed -= size;
}
CachedPixels* SkLruImageCache::findByID(intptr_t ID) const {
// Mutex is already locked.
Iter iter;
// Start from the head, most recently used.
CachedPixels* pixels = iter.init(fLRU, Iter::kHead_IterStart);
while (pixels != NULL) {
if (pixels->getID() == ID) {
return pixels;
}
pixels = iter.next();
}
return NULL;
}
void SkLruImageCache::purgeIfNeeded() {
// Mutex is already locked.
this->purgeTilAtOrBelow(fRamBudget);
}
void SkLruImageCache::purgeTilAtOrBelow(size_t limit) {
// Mutex is already locked.
if (fRamUsed > limit) {
Iter iter;
// Start from the tail, least recently used.
CachedPixels* pixels = iter.init(fLRU, Iter::kTail_IterStart);
while (pixels != NULL && fRamUsed > limit) {
CachedPixels* prev = iter.prev();
if (!pixels->isLocked()) {
this->removePixels(pixels);
}
pixels = prev;
}
}
}
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