Chris@102: // Copyright (C) 2013-2014 Vicente J. Botet Escriba
Chris@102: //
Chris@102: //  Distributed under the Boost Software License, Version 1.0. (See accompanying
Chris@102: //  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
Chris@102: //
Chris@102: // 2013/09 Vicente J. Botet Escriba
Chris@102: //    Adapt to boost from CCIA C++11 implementation
Chris@102: //    first implementation of a simple pool thread using a vector of threads and a sync_queue.
Chris@102: 
Chris@102: #ifndef BOOST_THREAD_EXECUTORS_BASIC_THREAD_POOL_HPP
Chris@102: #define BOOST_THREAD_EXECUTORS_BASIC_THREAD_POOL_HPP
Chris@102: 
Chris@102: #include <boost/thread/detail/config.hpp>
Chris@102: #include <boost/thread/detail/delete.hpp>
Chris@102: #include <boost/thread/detail/move.hpp>
Chris@102: #include <boost/thread/scoped_thread.hpp>
Chris@102: #include <boost/thread/concurrent_queues/sync_queue.hpp>
Chris@102: #include <boost/thread/executors/work.hpp>
Chris@102: #include <boost/thread/csbl/vector.hpp>
Chris@102: 
Chris@102: #include <boost/config/abi_prefix.hpp>
Chris@102: 
Chris@102: namespace boost
Chris@102: {
Chris@102: namespace executors
Chris@102: {
Chris@102:   class basic_thread_pool
Chris@102:   {
Chris@102:   public:
Chris@102:     /// type-erasure to store the works to do
Chris@102:     typedef  executors::work work;
Chris@102:   private:
Chris@102:     /// the kind of stored threads are scoped threads to ensure that the threads are joined.
Chris@102:     /// A move aware vector type
Chris@102:     typedef scoped_thread<> thread_t;
Chris@102:     typedef csbl::vector<thread_t> thread_vector;
Chris@102: 
Chris@102:     /// the thread safe work queue
Chris@102:     concurrent::sync_queue<work > work_queue;
Chris@102:     /// A move aware vector
Chris@102:     thread_vector threads;
Chris@102: 
Chris@102:   public:
Chris@102:     /**
Chris@102:      * Effects: try to execute one task.
Chris@102:      * Returns: whether a task has been executed.
Chris@102:      * Throws: whatever the current task constructor throws or the task() throws.
Chris@102:      */
Chris@102:     bool try_executing_one()
Chris@102:     {
Chris@102:       try
Chris@102:       {
Chris@102:         work task;
Chris@102:         if (work_queue.try_pull(task) == queue_op_status::success)
Chris@102:         {
Chris@102:           task();
Chris@102:           return true;
Chris@102:         }
Chris@102:         return false;
Chris@102:       }
Chris@102:       catch (...)
Chris@102:       {
Chris@102:         std::terminate();
Chris@102:         return false;
Chris@102:       }
Chris@102:     }
Chris@102:     /**
Chris@102:      * Effects: schedule one task or yields
Chris@102:      * Throws: whatever the current task constructor throws or the task() throws.
Chris@102:      */
Chris@102:     void schedule_one_or_yield()
Chris@102:     {
Chris@102:         if ( ! try_executing_one())
Chris@102:         {
Chris@102:           this_thread::yield();
Chris@102:         }
Chris@102:     }
Chris@102:   private:
Chris@102: 
Chris@102:     /**
Chris@102:      * The main loop of the worker threads
Chris@102:      */
Chris@102:     void worker_thread()
Chris@102:     {
Chris@102:       try
Chris@102:       {
Chris@102:         for(;;)
Chris@102:         {
Chris@102:           work task;
Chris@102:           queue_op_status st = work_queue.wait_pull(task);
Chris@102:           if (st == queue_op_status::closed) return;
Chris@102:           task();
Chris@102:         }
Chris@102:       }
Chris@102:       catch (...)
Chris@102:       {
Chris@102:         std::terminate();
Chris@102:         return;
Chris@102:       }
Chris@102:     }
Chris@102: #if defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
Chris@102:     template <class AtThreadEntry>
Chris@102:     void worker_thread1(AtThreadEntry& at_thread_entry)
Chris@102:     {
Chris@102:       at_thread_entry(*this);
Chris@102:       worker_thread();
Chris@102:     }
Chris@102: #endif
Chris@102:     void worker_thread2(void(*at_thread_entry)(basic_thread_pool&))
Chris@102:     {
Chris@102:       at_thread_entry(*this);
Chris@102:       worker_thread();
Chris@102:     }
Chris@102:     template <class AtThreadEntry>
Chris@102:     void worker_thread3(BOOST_THREAD_FWD_REF(AtThreadEntry) at_thread_entry)
Chris@102:     {
Chris@102:       at_thread_entry(*this);
Chris@102:       worker_thread();
Chris@102:     }
Chris@102:     static void do_nothing_at_thread_entry(basic_thread_pool&) {}
Chris@102: 
Chris@102:   public:
Chris@102:     /// basic_thread_pool is not copyable.
Chris@102:     BOOST_THREAD_NO_COPYABLE(basic_thread_pool)
Chris@102: 
Chris@102:     /**
Chris@102:      * \b Effects: creates a thread pool that runs closures on \c thread_count threads.
Chris@102:      *
Chris@102:      * \b Throws: Whatever exception is thrown while initializing the needed resources.
Chris@102:      */
Chris@102:     basic_thread_pool(unsigned const thread_count = thread::hardware_concurrency()+1)
Chris@102:     {
Chris@102:       try
Chris@102:       {
Chris@102:         threads.reserve(thread_count);
Chris@102:         for (unsigned i = 0; i < thread_count; ++i)
Chris@102:         {
Chris@102: #if 1
Chris@102:           thread th (&basic_thread_pool::worker_thread, this);
Chris@102:           threads.push_back(thread_t(boost::move(th)));
Chris@102: #else
Chris@102:           threads.push_back(thread_t(&basic_thread_pool::worker_thread, this)); // do not compile
Chris@102: #endif
Chris@102:         }
Chris@102:       }
Chris@102:       catch (...)
Chris@102:       {
Chris@102:         close();
Chris@102:         throw;
Chris@102:       }
Chris@102:     }
Chris@102:     /**
Chris@102:      * \b Effects: creates a thread pool that runs closures on \c thread_count threads
Chris@102:      * and executes the at_thread_entry function at the entry of each created thread. .
Chris@102:      *
Chris@102:      * \b Throws: Whatever exception is thrown while initializing the needed resources.
Chris@102:      */
Chris@102: #if defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
Chris@102:     template <class AtThreadEntry>
Chris@102:     basic_thread_pool( unsigned const thread_count, AtThreadEntry& at_thread_entry)
Chris@102:     {
Chris@102:       try
Chris@102:       {
Chris@102:         threads.reserve(thread_count);
Chris@102:         for (unsigned i = 0; i < thread_count; ++i)
Chris@102:         {
Chris@102:           thread th (&basic_thread_pool::worker_thread1<AtThreadEntry>, this, at_thread_entry);
Chris@102:           threads.push_back(thread_t(boost::move(th)));
Chris@102:           //threads.push_back(thread_t(&basic_thread_pool::worker_thread, this)); // do not compile
Chris@102:         }
Chris@102:       }
Chris@102:       catch (...)
Chris@102:       {
Chris@102:         close();
Chris@102:         throw;
Chris@102:       }
Chris@102:     }
Chris@102: #endif
Chris@102:     basic_thread_pool( unsigned const thread_count, void(*at_thread_entry)(basic_thread_pool&))
Chris@102:     {
Chris@102:       try
Chris@102:       {
Chris@102:         threads.reserve(thread_count);
Chris@102:         for (unsigned i = 0; i < thread_count; ++i)
Chris@102:         {
Chris@102:           thread th (&basic_thread_pool::worker_thread2, this, at_thread_entry);
Chris@102:           threads.push_back(thread_t(boost::move(th)));
Chris@102:           //threads.push_back(thread_t(&basic_thread_pool::worker_thread, this)); // do not compile
Chris@102:         }
Chris@102:       }
Chris@102:       catch (...)
Chris@102:       {
Chris@102:         close();
Chris@102:         throw;
Chris@102:       }
Chris@102:     }
Chris@102:     template <class AtThreadEntry>
Chris@102:     basic_thread_pool( unsigned const thread_count, BOOST_THREAD_FWD_REF(AtThreadEntry) at_thread_entry)
Chris@102:     {
Chris@102:       try
Chris@102:       {
Chris@102:         threads.reserve(thread_count);
Chris@102:         for (unsigned i = 0; i < thread_count; ++i)
Chris@102:         {
Chris@102:           thread th (&basic_thread_pool::worker_thread3<AtThreadEntry>, this, boost::forward<AtThreadEntry>(at_thread_entry));
Chris@102:           threads.push_back(thread_t(boost::move(th)));
Chris@102:           //threads.push_back(thread_t(&basic_thread_pool::worker_thread, this)); // do not compile
Chris@102:         }
Chris@102:       }
Chris@102:       catch (...)
Chris@102:       {
Chris@102:         close();
Chris@102:         throw;
Chris@102:       }
Chris@102:     }
Chris@102:     /**
Chris@102:      * \b Effects: Destroys the thread pool.
Chris@102:      *
Chris@102:      * \b Synchronization: The completion of all the closures happen before the completion of the \c basic_thread_pool destructor.
Chris@102:      */
Chris@102:     ~basic_thread_pool()
Chris@102:     {
Chris@102:       // signal to all the worker threads that there will be no more submissions.
Chris@102:       close();
Chris@102:       // joins all the threads as the threads were scoped_threads
Chris@102:     }
Chris@102: 
Chris@102:     /**
Chris@102:      * \b Effects: join all the threads.
Chris@102:      */
Chris@102:     void join()
Chris@102:     {
Chris@102:       for (unsigned i = 0; i < threads.size(); ++i)
Chris@102:       {
Chris@102:         threads[i].join();
Chris@102:       }
Chris@102:     }
Chris@102: 
Chris@102:     /**
Chris@102:      * \b Effects: close the \c basic_thread_pool for submissions.
Chris@102:      * The worker threads will work until there is no more closures to run.
Chris@102:      */
Chris@102:     void close()
Chris@102:     {
Chris@102:       work_queue.close();
Chris@102:     }
Chris@102: 
Chris@102:     /**
Chris@102:      * \b Returns: whether the pool is closed for submissions.
Chris@102:      */
Chris@102:     bool closed()
Chris@102:     {
Chris@102:       return work_queue.closed();
Chris@102:     }
Chris@102: 
Chris@102:     /**
Chris@102:      * \b Requires: \c Closure is a model of \c Callable(void()) and a model of \c CopyConstructible/MoveConstructible.
Chris@102:      *
Chris@102:      * \b Effects: The specified \c closure will be scheduled for execution at some point in the future.
Chris@102:      * If invoked closure throws an exception the \c basic_thread_pool will call \c std::terminate, as is the case with threads.
Chris@102:      *
Chris@102:      * \b Synchronization: completion of \c closure on a particular thread happens before destruction of thread's thread local variables.
Chris@102:      *
Chris@102:      * \b Throws: \c sync_queue_is_closed if the thread pool is closed.
Chris@102:      * Whatever exception that can be throw while storing the closure.
Chris@102:      */
Chris@102: 
Chris@102: #if defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
Chris@102:     template <typename Closure>
Chris@102:     void submit(Closure & closure)
Chris@102:     {
Chris@102:       work_queue.push(work(closure));
Chris@102:     }
Chris@102: #endif
Chris@102:     void submit(void (*closure)())
Chris@102:     {
Chris@102:       work_queue.push(work(closure));
Chris@102:     }
Chris@102: 
Chris@102:     template <typename Closure>
Chris@102:     void submit(BOOST_THREAD_RV_REF(Closure) closure)
Chris@102:     {
Chris@102:       work_queue.push(work(boost::forward<Closure>(closure)));
Chris@102:     }
Chris@102: 
Chris@102:     /**
Chris@102:      * \b Requires: This must be called from an scheduled task.
Chris@102:      *
Chris@102:      * \b Effects: reschedule functions until pred()
Chris@102:      */
Chris@102:     template <typename Pred>
Chris@102:     bool reschedule_until(Pred const& pred)
Chris@102:     {
Chris@102:       do {
Chris@102:         if ( ! try_executing_one())
Chris@102:         {
Chris@102:           return false;
Chris@102:         }
Chris@102:       } while (! pred());
Chris@102:       return true;
Chris@102:     }
Chris@102: 
Chris@102:   };
Chris@102: }
Chris@102: using executors::basic_thread_pool;
Chris@102: 
Chris@102: }
Chris@102: 
Chris@102: #include <boost/config/abi_suffix.hpp>
Chris@102: 
Chris@102: #endif