ThreadPool.h

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/*
 * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License").
 * You may not use this file except in compliance with the License.
 * A copy of the License is located at
 *
 *     http://aws.amazon.com/apache2.0/
 *
 * or in the "license" file accompanying this file. This file 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 ALEXA_CLIENT_SDK_AVSCOMMON_UTILS_INCLUDE_AVSCOMMON_UTILS_THREADING_THREADPOOL_H_
#define ALEXA_CLIENT_SDK_AVSCOMMON_UTILS_INCLUDE_AVSCOMMON_UTILS_THREADING_THREADPOOL_H_

#include <condition_variable>
#include <list>
#include <string>

#include "WorkerThread.h"

namespace alexaClientSDK {
namespace avsCommon {
namespace utils {
namespace threading {

static const size_t DEFAULT_MAX_THREAD_POOL_THREADS = 20;

class ThreadPool {
public:
    ThreadPool(size_t maxThreads = DEFAULT_MAX_THREAD_POOL_THREADS);

    ~ThreadPool();

    std::unique_ptr<WorkerThread> obtainWorker();

    void releaseWorker(std::unique_ptr<WorkerThread> workerThread);

    void setMaxThreads(size_t maxThreads);

    size_t getMaxThreads();

    void getStats(
        uint64_t& threadsCreated,
        uint64_t& threadsObtained,
        uint64_t& threadsReleasedToPool,
        uint64_t& threadsReleasedFromPool);

    static std::shared_ptr<ThreadPool> getDefaultThreadPool();

private:
    std::list<std::unique_ptr<WorkerThread>> m_workerQueue;

    size_t m_maxPoolThreads;

    uint64_t m_created;

    uint64_t m_obtained;

    uint64_t m_releasedToPool;

    uint64_t m_releasedFromPool;

    std::mutex m_queueMutex;
};

}  // namespace threading
}  // namespace utils
}  // namespace avsCommon
}  // namespace alexaClientSDK

#endif  // ALEXA_CLIENT_SDK_AVSCOMMON_UTILS_INCLUDE_AVSCOMMON_UTILS_THREADING_THREADPOOL_H_