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* Copyright 2014 Google Inc.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
#ifndef SkCachedData_DEFINED
#define SkCachedData_DEFINED
#include "SkMutex.h"
#include "SkTypes.h"
class SkDiscardableMemory;
class SkCachedData : ::SkNoncopyable {
SkCachedData(void* mallocData, size_t size);
SkCachedData(size_t size, SkDiscardableMemory*);
virtual ~SkCachedData();
size_t size() const { return fSize; }
const void* data() const { return fData; }
void* writable_data() { return fData; }
void ref() const { this->internalRef(false); }
void unref() const { this->internalUnref(false); }
int testing_only_getRefCnt() const { return fRefCnt; }
bool testing_only_isLocked() const { return fIsLocked; }
bool testing_only_isInCache() const { return fInCache; }
SkDiscardableMemory* diagnostic_only_getDiscardable() const {
return kDiscardableMemory_StorageType == fStorageType ? fStorage.fDM : nullptr;
// called when fData changes. could be nullptr.
virtual void onDataChange(void* oldData, void* newData) {}
SkMutex fMutex; // could use a pool of these...
enum StorageType {
union {
SkDiscardableMemory* fDM;
void* fMalloc;
} fStorage;
void* fData;
size_t fSize;
int fRefCnt; // low-bit means we're owned by the cache
StorageType fStorageType;
bool fInCache;
bool fIsLocked;
void internalRef(bool fromCache) const;
void internalUnref(bool fromCache) const;
void inMutexRef(bool fromCache);
bool inMutexUnref(bool fromCache); // returns true if we should delete "this"
void inMutexLock();
void inMutexUnlock();
// called whenever our fData might change (lock or unlock)
void setData(void* newData) {
if (newData != fData) {
// notify our subclasses of the change
this->onDataChange(fData, newData);
fData = newData;
class AutoMutexWritable;
#ifdef SK_DEBUG
void validate() const;
void validate() const {}
* Attaching a data to to a SkResourceCache (only one at a time) enables the data to be
* unlocked when the cache is the only owner, thus freeing it to be purged (assuming the
* data is backed by a SkDiscardableMemory).
* When attached, it also automatically attempts to "lock" the data when the first client
* ref's the data (typically from a find(key, visitor) call).
* Thus the data will always be "locked" when a non-cache has a ref on it (whether or not
* the lock succeeded to recover the memory -- check data() to see if it is nullptr).
* Call when adding this instance to a SkResourceCache::Rec subclass
* (typically in the Rec's constructor).
void attachToCacheAndRef() const { this->internalRef(true); }
* Call when removing this instance from a SkResourceCache::Rec subclass
* (typically in the Rec's destructor).
void detachFromCacheAndUnref() const { this->internalUnref(true); }