threadpool.hxx

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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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 * License, v. 2.0. If a copy of the MPL was not distributed with this
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 */

#ifndef INCLUDED_COMPHELPER_THREADPOOL_HXX
#define INCLUDED_COMPHELPER_THREADPOOL_HXX

#include <sal/config.h>
#include <rtl/ref.hxx>
#include <comphelper/comphelperdllapi.h>
#include <mutex>
#include <condition_variable>
#include <vector>
#include <memory>

namespace comphelper
{
class ThreadTaskTag;

class COMPHELPER_DLLPUBLIC ThreadTask
{
friend class ThreadPool;
friend struct std::default_delete<ThreadTask>;
    std::shared_ptr<ThreadTaskTag>  mpTag;

    void      exec();
protected:
    virtual void doWork() = 0;
    virtual   ~ThreadTask() {}
public:
    ThreadTask(const std::shared_ptr<ThreadTaskTag>& pTag);
};

class COMPHELPER_DLLPUBLIC ThreadPool final
{
public:
    static      ThreadPool& getSharedOptimalPool();

    static std::shared_ptr<ThreadTaskTag> createThreadTaskTag();

    static bool isTaskTagDone(const std::shared_ptr<ThreadTaskTag>&);

    static      sal_Int32 getPreferredConcurrency();

    ThreadPool( sal_Int32 nWorkers );
    ~ThreadPool();

    void        pushTask( std::unique_ptr<ThreadTask> pTask);

    void        waitUntilDone(const std::shared_ptr<ThreadTaskTag>&, bool bJoin = true);

    void        joinThreadsIfIdle();

    bool        isIdle() const { return maTasks.empty() && mnBusyWorkers == 0; };

    sal_Int32   getWorkerCount() const { return mnMaxWorkers; }

    void        shutdown();

private:
    ThreadPool(const ThreadPool&) = delete;
    ThreadPool& operator=(const ThreadPool&) = delete;

    class ThreadWorker;
    friend class ThreadWorker;

    std::unique_ptr<ThreadTask> popWorkLocked( std::unique_lock< std::mutex > & rGuard, bool bWait );
    void shutdownLocked(std::unique_lock<std::mutex>&);
    void incBusyWorker();
    void decBusyWorker();

    std::mutex              maMutex;
    std::condition_variable maTasksChanged;
    bool                    mbTerminate;
    std::size_t const       mnMaxWorkers;
    std::size_t             mnBusyWorkers;
    std::vector< std::unique_ptr<ThreadTask> >   maTasks;
    std::vector< rtl::Reference< ThreadWorker > > maWorkers;
};

} // namespace comphelper

#endif // INCLUDED_COMPHELPER_THREADPOOL_HXX

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