src/gpu/GrSemaphore.h

/*
 * Copyright 2017 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#ifndef GrSemaphore_DEFINED
#define GrSemaphore_DEFINED

#include "SkRefCnt.h"

class GrBackendSemaphore;
class GrGpu;

/*
 * Wrapper around a semaphore object which must be implemented on each backend. This semaphores can
 * at most be signaled once and waited upon once.
 */
class GrSemaphore : public SkRefCnt {
public:
    bool hasSubmittedSignal() const { return fSignaled; }
    bool hasSubmittedWait() const { return fWaitedOn; }

private:
    // This function should only be used in the case of exporting and importing a GrSemaphore object
    // from one GrContext to another. When exporting, the GrSemaphore should be set to a null GrGpu,
    // and when importing it should be set to the GrGpu of the current context. Once exported, a
    // GrSemaphore should not be used with its old context.
    void resetGpu(const GrGpu* gpu) { fGpu = gpu; }

    // The derived class will init the GrBackendSemaphore. This is used when flushing with signal
    // semaphores so we can set the clients GrBackendSemaphore object after we've created the
    // internal semaphore.
    virtual void setBackendSemaphore(GrBackendSemaphore*) const = 0;

    bool fSignaled = false;
    bool fWaitedOn = false;

protected:
    explicit GrSemaphore(const GrGpu* gpu) : fGpu(gpu) {}

    friend class GrGpu; // setBackendSemaphore
    friend class GrRenderTargetContext; // setBackendSemaphore
    friend class GrResourceProvider; // resetGpu

    const GrGpu* fGpu;
};

#endif