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 SkDiscardableMemory_DEFINED
michael@0: #define SkDiscardableMemory_DEFINED
michael@0: 
michael@0: #include "SkRefCnt.h"
michael@0: #include "SkTypes.h"
michael@0: 
michael@0: /**
michael@0:  *  Interface for discardable memory. Implementation is provided by the
michael@0:  *  embedder.
michael@0:  */
michael@0: class SK_API SkDiscardableMemory {
michael@0: public:
michael@0:     /**
michael@0:      *  Factory method that creates, initializes and locks an SkDiscardableMemory
michael@0:      *  object. If either of these steps fails, a NULL pointer will be returned.
michael@0:      */
michael@0:     static SkDiscardableMemory* Create(size_t bytes);
michael@0: 
michael@0:     /**
michael@0:      *  Factory class that creates, initializes and locks an SkDiscardableMemory
michael@0:      *  object. If either of these steps fails, a NULL pointer will be returned.
michael@0:      */
michael@0:     class Factory : public SkRefCnt {
michael@0:     public:
michael@0:         virtual SkDiscardableMemory* create(size_t bytes) = 0;
michael@0:     private:
michael@0:         typedef SkRefCnt INHERITED;
michael@0:     };
michael@0: 
michael@0:     /** Must not be called while locked.
michael@0:      */
michael@0:     virtual ~SkDiscardableMemory() {}
michael@0: 
michael@0:     /**
michael@0:      * Locks the memory, prevent it from being discarded. Once locked. you may
michael@0:      * obtain a pointer to that memory using the data() method.
michael@0:      *
michael@0:      * lock() may return false, indicating that the underlying memory was
michael@0:      * discarded and that the lock failed.
michael@0:      *
michael@0:      * Nested calls to lock are not allowed.
michael@0:      */
michael@0:     virtual bool lock() = 0;
michael@0: 
michael@0:     /**
michael@0:      * Returns the current pointer for the discardable memory. This call is ONLY
michael@0:      * valid when the discardable memory object is locked.
michael@0:      */
michael@0:     virtual void* data() = 0;
michael@0: 
michael@0:     /**
michael@0:      * Unlock the memory so that it can be purged by the system. Must be called
michael@0:      * after every successful lock call.
michael@0:      */
michael@0:     virtual void unlock() = 0;
michael@0: };
michael@0: 
michael@0: #endif