replicant-frameworks_native/services/surfaceflinger/Barrier.h

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/*
* Copyright (C) 2007 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_BARRIER_H
#define ANDROID_BARRIER_H
#include <stdint.h>
#include <sys/types.h>
#include <utils/threads.h>
namespace android {
class Barrier
{
public:
inline Barrier() : state(CLOSED) { }
inline ~Barrier() { }
// Release any threads waiting at the Barrier.
// Provides release semantics: preceding loads and stores will be visible
// to other threads before they wake up.
void open() {
Mutex::Autolock _l(lock);
state = OPENED;
cv.broadcast();
}
// Reset the Barrier, so wait() will block until open() has been called.
void close() {
Mutex::Autolock _l(lock);
state = CLOSED;
}
// Wait until the Barrier is OPEN.
// Provides acquire semantics: no subsequent loads or stores will occur
// until wait() returns.
void wait() const {
Mutex::Autolock _l(lock);
while (state == CLOSED) {
cv.wait(lock);
}
}
private:
enum { OPENED, CLOSED };
mutable Mutex lock;
mutable Condition cv;
volatile int state;
};
}; // namespace android
#endif // ANDROID_BARRIER_H