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/*
* Copyright (C) 2013 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_HWUI_FENCE_H
#define ANDROID_HWUI_FENCE_H
#include <EGL/egl.h>
#include <EGL/eglext.h>
namespace android {
namespace uirenderer {
/**
* Creating a Fence instance inserts a new sync fence in the OpenGL
* commands stream. The caller can then wait for the fence to be signaled
* by calling the wait method.
*/
class Fence {
public:
enum {
/**
* Default timeout in nano-seconds for wait()
*/
kDefaultTimeout = 1000000000
};
/**
* Inserts a new sync fence in the OpenGL commands stream.
*/
Fence() {
mDisplay = eglGetDisplay(EGL_DEFAULT_DISPLAY);
if (mDisplay != EGL_NO_DISPLAY) {
mFence = eglCreateSyncKHR(mDisplay, EGL_SYNC_FENCE_KHR, NULL);
} else {
mFence = EGL_NO_SYNC_KHR;
}
}
/**
* Destroys the fence. Any caller waiting on the fence will be
* signaled immediately.
*/
~Fence() {
if (mFence != EGL_NO_SYNC_KHR) {
eglDestroySyncKHR(mDisplay, mFence);
}
}
/**
* Blocks the calling thread until this fence is signaled, or until
* <timeout> nanoseconds have passed.
*
* Returns true if waiting for the fence was successful, false if
* a timeout or an error occurred.
*/
bool wait(EGLTimeKHR timeout = kDefaultTimeout) {
EGLint waitStatus = eglClientWaitSyncKHR(mDisplay, mFence,
EGL_SYNC_FLUSH_COMMANDS_BIT_KHR, timeout);
if (waitStatus == EGL_FALSE) {
ALOGW("Failed to wait for the fence %#x", eglGetError());
}
return waitStatus == EGL_CONDITION_SATISFIED_KHR;
}
private:
EGLDisplay mDisplay;
EGLSyncKHR mFence;
}; // class Fence
/**
* An AutoFence creates a Fence instance and waits for the fence
* to be signaled when the AutoFence is destroyed. This is useful
* to automatically wait for a series of OpenGL commands to be
* executed. For example:
*
* void drawAndWait() {
* glDrawElements();
* AutoFence fence;
* }
*/
class AutoFence {
public:
AutoFence(EGLTimeKHR timeout = Fence::kDefaultTimeout): mTimeout(timeout) {
}
~AutoFence() {
mFence.wait(mTimeout);
}
private:
EGLTimeKHR mTimeout;
Fence mFence;
}; // class AutoFence
}; // namespace uirenderer
}; // namespace android
#endif // ANDROID_HWUI_FENCE_H
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