| // Copyright (C) 2013 Vicente J. Botet Escriba |
| // |
| // Distributed under the Boost Software License, Version 1.0. (See accompanying |
| // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) |
| // |
| // 2013/11 Vicente J. Botet Escriba |
| // first implementation of a simple serial scheduler. |
| |
| #ifndef BOOST_THREAD_SERIAL_EXECUTOR_HPP |
| #define BOOST_THREAD_SERIAL_EXECUTOR_HPP |
| |
| #include <boost/thread/detail/config.hpp> |
| #include <boost/thread/detail/delete.hpp> |
| #include <boost/thread/detail/move.hpp> |
| #include <boost/thread/concurrent_queues/sync_queue.hpp> |
| #include <boost/thread/executors/work.hpp> |
| #include <boost/thread/executors/generic_executor_ref.hpp> |
| #include <boost/thread/future.hpp> |
| #include <boost/thread/scoped_thread.hpp> |
| |
| #include <boost/config/abi_prefix.hpp> |
| |
| namespace boost |
| { |
| namespace executors |
| { |
| class serial_executor |
| { |
| public: |
| /// type-erasure to store the works to do |
| typedef executors::work work; |
| private: |
| typedef scoped_thread<> thread_t; |
| |
| /// the thread safe work queue |
| concurrent::sync_queue<work > work_queue; |
| generic_executor_ref ex; |
| thread_t thr; |
| |
| struct try_executing_one_task { |
| work& task; |
| boost::promise<void> &p; |
| try_executing_one_task(work& task, boost::promise<void> &p) |
| : task(task), p(p) {} |
| void operator()() { |
| try { |
| task(); |
| p.set_value(); |
| } catch (...) |
| { |
| p.set_exception(current_exception()); |
| } |
| } |
| }; |
| public: |
| /** |
| * \par Returns |
| * The underlying executor wrapped on a generic executor reference. |
| */ |
| generic_executor_ref& underlying_executor() BOOST_NOEXCEPT { return ex; } |
| |
| /** |
| * Effects: try to execute one task. |
| * Returns: whether a task has been executed. |
| * Throws: whatever the current task constructor throws or the task() throws. |
| */ |
| bool try_executing_one() |
| { |
| work task; |
| try |
| { |
| if (work_queue.try_pull(task) == queue_op_status::success) |
| { |
| boost::promise<void> p; |
| try_executing_one_task tmp(task,p); |
| ex.submit(tmp); |
| p.get_future().wait(); |
| return true; |
| } |
| return false; |
| } |
| catch (...) |
| { |
| std::terminate(); |
| return false; |
| } |
| } |
| private: |
| /** |
| * Effects: schedule one task or yields |
| * Throws: whatever the current task constructor throws or the task() throws. |
| */ |
| void schedule_one_or_yield() |
| { |
| if ( ! try_executing_one()) |
| { |
| this_thread::yield(); |
| } |
| } |
| |
| /** |
| * The main loop of the worker thread |
| */ |
| void worker_thread() |
| { |
| while (!closed()) |
| { |
| schedule_one_or_yield(); |
| } |
| while (try_executing_one()) |
| { |
| } |
| } |
| |
| public: |
| /// serial_executor is not copyable. |
| BOOST_THREAD_NO_COPYABLE(serial_executor) |
| |
| /** |
| * \b Effects: creates a thread pool that runs closures using one of its closure-executing methods. |
| * |
| * \b Throws: Whatever exception is thrown while initializing the needed resources. |
| */ |
| template <class Executor> |
| serial_executor(Executor& ex) |
| : ex(ex), thr(&serial_executor::worker_thread, this) |
| { |
| } |
| /** |
| * \b Effects: Destroys the thread pool. |
| * |
| * \b Synchronization: The completion of all the closures happen before the completion of the \c serial_executor destructor. |
| */ |
| ~serial_executor() |
| { |
| // signal to the worker thread that there will be no more submissions. |
| close(); |
| } |
| |
| /** |
| * \b Effects: close the \c serial_executor for submissions. |
| * The loop will work until there is no more closures to run. |
| */ |
| void close() |
| { |
| work_queue.close(); |
| } |
| |
| /** |
| * \b Returns: whether the pool is closed for submissions. |
| */ |
| bool closed() |
| { |
| return work_queue.closed(); |
| } |
| |
| /** |
| * \b Requires: \c Closure is a model of \c Callable(void()) and a model of \c CopyConstructible/MoveConstructible. |
| * |
| * \b Effects: The specified \c closure will be scheduled for execution at some point in the future. |
| * If invoked closure throws an exception the \c serial_executor will call \c std::terminate, as is the case with threads. |
| * |
| * \b Synchronization: completion of \c closure on a particular thread happens before destruction of thread's thread local variables. |
| * |
| * \b Throws: \c sync_queue_is_closed if the thread pool is closed. |
| * Whatever exception that can be throw while storing the closure. |
| */ |
| |
| #if defined(BOOST_NO_CXX11_RVALUE_REFERENCES) |
| template <typename Closure> |
| void submit(Closure & closure) |
| { |
| work_queue.push(work(closure)); |
| } |
| #endif |
| void submit(void (*closure)()) |
| { |
| work_queue.push(work(closure)); |
| } |
| |
| template <typename Closure> |
| void submit(BOOST_THREAD_RV_REF(Closure) closure) |
| { |
| work_queue.push(work(boost::forward<Closure>(closure))); |
| } |
| |
| /** |
| * \b Requires: This must be called from an scheduled task. |
| * |
| * \b Effects: reschedule functions until pred() |
| */ |
| template <typename Pred> |
| bool reschedule_until(Pred const& pred) |
| { |
| do { |
| if ( ! try_executing_one()) |
| { |
| return false; |
| } |
| } while (! pred()); |
| return true; |
| } |
| |
| }; |
| } |
| using executors::serial_executor; |
| } |
| |
| #include <boost/config/abi_suffix.hpp> |
| |
| #endif |