michael@0: /*
michael@0:  * Copyright 2013 Google Inc.
michael@0:  *
michael@0:  * Use of this source code is governed by a BSD-style license that can be
michael@0:  * found in the LICENSE file.
michael@0:  */
michael@0: 
michael@0: #ifndef SkPurgeableMemoryBlock_DEFINED
michael@0: #define SkPurgeableMemoryBlock_DEFINED
michael@0: 
michael@0: #include "SkTypes.h"
michael@0: 
michael@0: class SkPurgeableMemoryBlock : public SkNoncopyable {
michael@0: 
michael@0: public:
michael@0:     /**
michael@0:      *  Whether or not this platform has an implementation for purgeable memory.
michael@0:      */
michael@0:     static bool IsSupported();
michael@0: 
michael@0:     /**
michael@0:      *  Create a new purgeable memory block of 'size' bytes. Returns NULL if not supported on this
michael@0:      *  platform or on failure.
michael@0:      *  @param size Number of bytes requested.
michael@0:      *  @return A new block, or NULL on failure.
michael@0:      */
michael@0:     static SkPurgeableMemoryBlock* Create(size_t size);
michael@0: 
michael@0: #ifdef SK_DEBUG
michael@0:     /**
michael@0:      *  Whether the platform supports one shot purge of all unpinned blocks. If so,
michael@0:      *  PurgeAllUnpinnedBlocks will be used to test a purge. Otherwise, purge will be called on
michael@0:      *  individual blocks.
michael@0:      */
michael@0:     static bool PlatformSupportsPurgingAllUnpinnedBlocks();
michael@0: 
michael@0:     /**
michael@0:      *  Purge all unpinned blocks at once, if the platform supports it.
michael@0:      */
michael@0:     static bool PurgeAllUnpinnedBlocks();
michael@0: 
michael@0:     // If PlatformSupportsPurgingAllUnpinnedBlocks returns true, this will not be called, so it can
michael@0:     // simply return false.
michael@0:     bool purge();
michael@0: 
michael@0:     bool isPinned() const { return fPinned; }
michael@0: #endif
michael@0: 
michael@0:     ~SkPurgeableMemoryBlock();
michael@0: 
michael@0:     /**
michael@0:      *  Output parameter for pin(), stating whether the data has been retained.
michael@0:      */
michael@0:     enum PinResult {
michael@0:         /**
michael@0:          *  The data has been purged, or this is the first call to pin.
michael@0:          */
michael@0:         kUninitialized_PinResult,
michael@0: 
michael@0:         /**
michael@0:          *  The data has been retained. The memory contains the same data it held when unpin() was
michael@0:          *  called.
michael@0:          */
michael@0:         kRetained_PinResult,
michael@0:     };
michael@0: 
michael@0:     /**
michael@0:      *  Pin the memory for use. Must not be called while already pinned.
michael@0:      *  @param PinResult Whether the data was retained. Ignored on failure.
michael@0:      *  @return Pointer to the pinned data on success. NULL on failure.
michael@0:      */
michael@0:     void* pin(PinResult*);
michael@0: 
michael@0:     /**
michael@0:      *  Unpin the data so it can be purged if necessary.
michael@0:      */
michael@0:     void unpin();
michael@0: 
michael@0: private:
michael@0:     void*       fAddr;
michael@0:     size_t      fSize;
michael@0:     bool        fPinned;
michael@0: #ifdef SK_BUILD_FOR_ANDROID
michael@0:     int         fFD;
michael@0: #endif
michael@0: 
michael@0:     // Unimplemented default constructor is private, to prevent manual creation.
michael@0:     SkPurgeableMemoryBlock();
michael@0: 
michael@0:     // The correct way to create a new one is from the static Create.
michael@0:     SkPurgeableMemoryBlock(size_t);
michael@0: };
michael@0: 
michael@0: #endif // SkPurgeableMemoryBlock_DEFINED