libui: add the Fence class

/*

 * Copyright (C) 2012 The Android Open Source Project

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 *      http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

#ifndef ANDROID_FENCE_H

#define ANDROID_FENCE_H

#include <stdint.h>

#include <limits.h>

#include <sys/types.h>

#include <ui/ANativeObjectBase.h>

#include <ui/PixelFormat.h>

#include <ui/Rect.h>

#include <utils/Flattenable.h>

#include <utils/String8.h>

struct ANativeWindowBuffer;

namespace android {

// ===========================================================================

// Fence

// ===========================================================================

class Fence

    : public LightRefBase<Fence>, public Flattenable

{

public:

    // Construct a new Fence object with an invalid file descriptor.  This

    // should be done when the Fence object will be set up by unflattening

    // serialized data.

    Fence();

    // Construct a new Fence object to manage a given fence file descriptor.

    // When the new Fence object is destructed the file descriptor will be

    // closed.

    Fence(int fenceFd);

    // wait waits for up to timeout milliseconds for the fence to signal.  If

    // the fence signals then NO_ERROR is returned. If the timeout expires

    // before the fence signals then -ETIME is returned.  A timeout of

    // TIMEOUT_NEVER may be used to indicate that the call should wait

    // indefinitely for the fence to signal.

    int wait(unsigned int timeout);

    // TIMEOUT_NEVER may be passed to the wait method to indicate that it

    // should wait indefinitely for the fence to signal.

    enum { TIMEOUT_NEVER = UINT_MAX };

    // merge combines two Fence objects, creating a new Fence object that

    // becomes signaled when both f1 and f2 are signaled (even if f1 or f2 is

    // destroyed before it becomes signaled).  The name argument specifies the

    // human-readable name to associated with the new Fence object.

    static sp<Fence> merge(const String8& name, const sp<Fence>& f1,

            const sp<Fence>& f2);

    // Flattenable interface

    size_t getFlattenedSize() const;

    size_t getFdCount() const;

    status_t flatten(void* buffer, size_t size,

            int fds[], size_t count) const;

    status_t unflatten(void const* buffer, size_t size,

            int fds[], size_t count);

private:

    // Only allow instantiation using ref counting.

    friend class LightRefBase<Fence>;

    virtual ~Fence();

    // Disallow copying

    Fence(const Fence& rhs);

    Fence& operator = (const Fence& rhs);

    const Fence& operator = (const Fence& rhs) const;

    int mFenceFd;

};

}; // namespace android

#endif // ANDROID_FENCE_H

/*

 * Copyright (C) 2012 The Android Open Source Project

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 *      http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

#define LOG_TAG "Fence"

#define ATRACE_TAG ATRACE_TAG_GRAPHICS

//#define LOG_NDEBUG 0

#include <sync/sync.h>

#include <ui/Fence.h>

#include <unistd.h>

#include <utils/Log.h>

#include <utils/Trace.h>

namespace android {

Fence::Fence() :

    mFenceFd(-1) {

}

Fence::Fence(int fenceFd) :

    mFenceFd(fenceFd) {

}

Fence::~Fence() {

    if (mFenceFd != -1) {

        close(mFenceFd);

    }

}

int Fence::wait(unsigned int timeout) {

    ATRACE_CALL();

    if (mFenceFd == -1) {

        return NO_ERROR;

    }

    return sync_wait(mFenceFd, timeout);

}

sp<Fence> Fence::merge(const String8& name, const sp<Fence>& f1,

        const sp<Fence>& f2) {

    ATRACE_CALL();

    int result = sync_merge(name.string(), f1->mFenceFd, f2->mFenceFd);

    if (result == -1) {

        ALOGE("merge: sync_merge returned an error: %s (%d)", strerror(-errno),

                errno);

        return sp<Fence>();

    }

    return sp<Fence>(new Fence(result));

}

size_t Fence::getFlattenedSize() const {

    return 0;

}

size_t Fence::getFdCount() const {

    return 1;

}

status_t Fence::flatten(void* buffer, size_t size, int fds[],

        size_t count) const {

    if (size != 0 || count != 1) {

        return BAD_VALUE;

    }

    fds[0] = mFenceFd;

    return NO_ERROR;

}

status_t Fence::unflatten(void const* buffer, size_t size, int fds[],

        size_t count) {

    if (size != 0 || count != 1) {

        return BAD_VALUE;

    }

    if (mFenceFd != -1) {

        // Don't unflatten if we already have a valid fd.

        return INVALID_OPERATION;

    }

    mFenceFd = fds[0];

    return NO_ERROR;

}

} // namespace android