/*

 * Copyright 2013 Google Inc.

 *

 * Use of this source code is governed by a BSD-style license that can be

 * found in the LICENSE file.

 */

#ifndef SkDiscardableMemory_DEFINED

#define SkDiscardableMemory_DEFINED

#include "include/core/SkRefCnt.h"

#include "include/core/SkTypes.h"

/**

 *  Interface for discardable memory. Implementation is provided by the

 *  embedder.

 */

class SK_SPI SkDiscardableMemory {

public:

    /**

     *  Factory method that creates, initializes and locks an SkDiscardableMemory

     *  object. If either of these steps fails, a nullptr pointer will be returned.

     */

    static SkDiscardableMemory* Create(size_t bytes);

    /**

     *  Factory class that creates, initializes and locks an SkDiscardableMemory

     *  object. If either of these steps fails, a nullptr pointer will be returned.

     */

    class Factory : public SkRefCnt {

    public:

        virtual SkDiscardableMemory* create(size_t bytes) = 0;

    private:

        using INHERITED = SkRefCnt;

    };

    /** Must not be called while locked.

     */

    virtual ~SkDiscardableMemory() {}

    /**

     * Locks the memory, prevent it from being discarded. Once locked. you may

     * obtain a pointer to that memory using the data() method.

     *

     * lock() may return false, indicating that the underlying memory was

     * discarded and that the lock failed.

     *

     * Nested calls to lock are not allowed.

     */

    [[nodiscard]] virtual bool lock() = 0;

    /**

     * Returns the current pointer for the discardable memory. This call is ONLY

     * valid when the discardable memory object is locked.

     */

    virtual void* data() = 0;

    /**

     * Unlock the memory so that it can be purged by the system. Must be called

     * after every successful lock call.

     */

    virtual void unlock() = 0;

protected:

    SkDiscardableMemory() = default;

    SkDiscardableMemory(const SkDiscardableMemory&) = delete;

    SkDiscardableMemory& operator=(const SkDiscardableMemory&) = delete;

};

#endif