1 files changed, 107 insertions, 0 deletions
diff --git a/include/comphelper/threadpool.hxx b/include/comphelper/threadpool.hxx
new file mode 100644
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+++ b/include/comphelper/threadpool.hxx
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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 <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(const 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      sal_Int32 getPreferredConcurrency();
+
+    ThreadPool( sal_Int32 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  bJoinAll - if set it joins all threads at the end if no other tasks from other tags.
+    */
+    void        waitUntilDone(const std::shared_ptr<ThreadTaskTag>&, bool bJoinAll = true);
+
+    /// join all threads if there are no tasks presently.
+    void        joinAll();
+
+    /// return the number of live worker threads
+    sal_Int32   getWorkerCount() const { return mnWorkers; }
+
+    /// 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>&);
+
+    /// signalled when all in-progress tasks are complete
+    std::mutex              maMutex;
+    std::condition_variable maTasksChanged;
+    bool                    mbTerminate;
+    std::size_t const       mnWorkers;
+    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: */