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/*
* Copyright 2018 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.
*/
#pragma once
#include <condition_variable>
#include <memory>
#include <mutex>
#include <base/macros.h>
namespace bluetooth {
namespace common {
/**
* A utility to wait for an event on another thread
*
* This class can be used once only. This means that after the first time
* NotifyFinished() is called, WaitForExecution() will no longer block. User
* needs to create a new instance if another ExecutionBarrier is needed.
*
* No reset mechanism is provided for this class to avoid racy scenarios and
* unsafe API usage
*
* Similar to std::experimental::barrier, but this can be used only once
*/
class ExecutionBarrier final {
public:
explicit ExecutionBarrier() : finished_(false){};
/**
* Blocks until NotifyFinished() is called on this object
*
*/
void WaitForExecution();
/**
* Unblocks any caller who are blocked on WaitForExecution() method call
*/
void NotifyFinished();
private:
bool finished_;
std::mutex execution_mutex_;
std::condition_variable execution_cv_;
/**
* Prevent COPY and ASSIGN since many internal states cannot be copied or
* assigned
*/
DISALLOW_COPY_AND_ASSIGN(ExecutionBarrier);
};
} // namespace common
} // namespace bluetooth
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