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/*
* Copyright 2011-2020 Blender Foundation
*
* 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 __UTIL_SEMAPHORE_H__
#define __UTIL_SEMAPHORE_H__
#include "util/thread.h"
CCL_NAMESPACE_BEGIN
/* Counting Semaphore
*
* To restrict concurrent access to a resource to a specified number
* of threads. Similar to std::counting_semaphore from C++20. */
class thread_counting_semaphore {
public:
explicit thread_counting_semaphore(const int count) : count(count)
{
}
thread_counting_semaphore(const thread_counting_semaphore &) = delete;
void acquire()
{
thread_scoped_lock lock(mutex);
while (count == 0) {
condition.wait(lock);
}
count--;
}
void release()
{
thread_scoped_lock lock(mutex);
count++;
condition.notify_one();
}
protected:
thread_mutex mutex;
thread_condition_variable condition;
int count;
};
CCL_NAMESPACE_END
#endif /* __UTIL_SEMAPHORE_H__ */
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