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- // 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>
- #if defined BOOST_THREAD_PROVIDES_FUTURE_CONTINUATION && defined BOOST_THREAD_PROVIDES_EXECUTORS && defined BOOST_THREAD_USES_MOVE
- #include <exception>
- #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>
- #if defined(BOOST_MSVC)
- # pragma warning(push)
- # pragma warning(disable: 4355) // 'this' : used in base member initializer list
- #endif
- 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.
- */
- void submit(BOOST_THREAD_RV_REF(work) closure)
- {
- work_queue.push(boost::move(closure));
- }
- #if defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
- template <typename Closure>
- void submit(Closure & closure)
- {
- submit(work(closure));
- }
- #endif
- void submit(void (*closure)())
- {
- submit(work(closure));
- }
- template <typename Closure>
- void submit(BOOST_THREAD_FWD_REF(Closure) closure)
- {
- work w((boost::forward<Closure>(closure)));
- submit(boost::move(w));
- }
- /**
- * \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;
- }
- #if defined(BOOST_MSVC)
- # pragma warning(pop)
- #endif
- #include <boost/config/abi_suffix.hpp>
- #endif
- #endif
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