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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/*
* This file is part of the LibreOffice project.
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/.
*/
#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 <cstddef>
#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;
/// execute this task
void exec();
protected:
/// override to get your task performed by the pool
virtual void doWork() = 0;
/// once pushed ThreadTasks are destroyed by the pool
virtual ~ThreadTask() {}
public:
ThreadTask(std::shared_ptr<ThreadTaskTag> pTag);
};
/// A very basic thread-safe thread pool implementation
class COMPHELPER_DLLPUBLIC ThreadPool final
{
public:
/// returns a pointer to a shared pool with optimal thread
/// count for the CPU
static ThreadPool& getSharedOptimalPool();
static std::shared_ptr<ThreadTaskTag> createThreadTaskTag();
static bool isTaskTagDone(const std::shared_ptr<ThreadTaskTag>&);
/// returns a configurable max-concurrency
/// limit to avoid spawning an unnecessarily
/// large number of threads on high-core boxes.
/// MAX_CONCURRENCY env. var. controls the cap.
static std::size_t getPreferredConcurrency();
ThreadPool( std::size_t nWorkers );
~ThreadPool();
/// push a new task onto the work queue
void pushTask( std::unique_ptr<ThreadTask> pTask);
/** Wait until all queued tasks associated with the tag are completed
@param bJoin - if set call joinThreadsIfIdle() at the end
*/
void waitUntilDone(const std::shared_ptr<ThreadTaskTag>&, bool bJoin = true);
/// join all threads if there are no tasks presently.
void joinThreadsIfIdle();
/// return true if there are no queued or worked-on tasks
bool isIdle() const { return maTasks.empty() && mnBusyWorkers == 0; };
/// return the number of live worker threads
sal_Int32 getWorkerCount() const { return mnMaxWorkers; }
/// wait until all work is completed, then join all threads
void shutdown();
private:
ThreadPool(const ThreadPool&) = delete;
ThreadPool& operator=(const ThreadPool&) = delete;
class ThreadWorker;
friend class ThreadWorker;
/** Pop a work task
@param bWait - if set wait until task present or termination
@return a new task to perform, or NULL if list empty or terminated
*/
std::unique_ptr<ThreadTask> popWorkLocked( std::unique_lock< std::mutex > & rGuard, bool bWait );
void shutdownLocked(std::unique_lock<std::mutex>&);
void incBusyWorker();
void decBusyWorker();
/// signalled when all in-progress tasks are complete
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
/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
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