// Copyright (C) 2015 Vicente J. Botet Escriba
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//
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// Distributed under the Boost Software License, Version 1.0. (See accompanying
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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//
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// 2013/11 Vicente J. Botet Escriba
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// first implementation of a simple serial scheduler.
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#ifndef BOOST_THREAD_SERIAL_EXECUTOR_CONT_HPP
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#define BOOST_THREAD_SERIAL_EXECUTOR_CONT_HPP
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#include <boost/thread/detail/config.hpp>
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#if defined BOOST_THREAD_PROVIDES_FUTURE_CONTINUATION && defined BOOST_THREAD_PROVIDES_EXECUTORS && defined BOOST_THREAD_USES_MOVE
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#include <exception> // std::terminate
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#include <boost/throw_exception.hpp>
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#include <boost/thread/detail/delete.hpp>
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#include <boost/thread/detail/move.hpp>
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#include <boost/thread/concurrent_queues/sync_queue.hpp>
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#include <boost/thread/executors/work.hpp>
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#include <boost/thread/executors/generic_executor_ref.hpp>
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#include <boost/thread/mutex.hpp>
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#include <boost/thread/future.hpp>
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#include <boost/thread/scoped_thread.hpp>
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#include <boost/thread/lock_guard.hpp>
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#include <boost/config/abi_prefix.hpp>
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namespace boost
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{
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namespace executors
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{
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class serial_executor_cont
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{
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public:
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/// type-erasure to store the works to do
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typedef executors::work work;
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private:
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generic_executor_ref ex_;
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BOOST_THREAD_FUTURE<void> fut_; // protected by mtx_
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bool closed_; // protected by mtx_
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mutex mtx_;
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struct continuation {
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work task;
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template <class X>
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struct result {
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typedef void type;
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};
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continuation(BOOST_THREAD_RV_REF(work) tsk)
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: task(boost::move(tsk)) {}
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void operator()(BOOST_THREAD_FUTURE<void> f)
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{
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try {
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task();
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} catch (...) {
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std::terminate();
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}
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}
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};
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bool closed(lock_guard<mutex>&) const
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{
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return closed_;
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}
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public:
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/**
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* \par Returns
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* The underlying executor wrapped on a generic executor reference.
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*/
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generic_executor_ref& underlying_executor() BOOST_NOEXCEPT { return ex_; }
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/// serial_executor_cont is not copyable.
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BOOST_THREAD_NO_COPYABLE(serial_executor_cont)
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/**
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* \b Effects: creates a serial executor that runs closures in fifo order using one the associated executor.
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*
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* \b Throws: Whatever exception is thrown while initializing the needed resources.
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*
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* \b Notes:
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* * The lifetime of the associated executor must outlive the serial executor.
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* * The current implementation doesn't support submission from synchronous continuation, that is,
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* - the executor must execute the continuation asynchronously or
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* - the continuation can not submit to this serial executor.
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*/
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template <class Executor>
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serial_executor_cont(Executor& ex)
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: ex_(ex), fut_(make_ready_future()), closed_(false)
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{
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}
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/**
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* \b Effects: Destroys the thread pool.
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*
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* \b Synchronization: The completion of all the closures happen before the completion of the \c serial_executor_cont destructor.
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*/
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~serial_executor_cont()
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{
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// signal to the worker thread that there will be no more submissions.
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close();
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}
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/**
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* \b Effects: close the \c serial_executor_cont for submissions.
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* The loop will work until there is no more closures to run.
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*/
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void close()
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{
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lock_guard<mutex> lk(mtx_);
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closed_ = true;;
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}
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/**
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* \b Returns: whether the pool is closed for submissions.
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*/
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bool closed()
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{
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lock_guard<mutex> lk(mtx_);
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return closed(lk);
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}
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/**
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* Effects: none.
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* Returns: always false.
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* Throws: No.
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* Remark: A serial executor can not execute one of its pending tasks as the tasks depends on the other tasks.
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*/
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bool try_executing_one()
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{
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return false;
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}
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/**
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* \b Requires: \c Closure is a model of \c Callable(void()) and a model of \c CopyConstructible/MoveConstructible.
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*
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* \b Effects: The specified \c closure will be scheduled for execution after the last submitted closure finish.
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* If the invoked closure throws an exception the \c serial_executor_cont will call \c std::terminate, as is the case with threads.
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*
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* \b Throws: \c sync_queue_is_closed if the executor is closed.
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* Whatever exception that can be throw while storing the closure.
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*
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*/
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#if defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
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template <typename Closure>
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void submit(Closure & closure)
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{
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lock_guard<mutex> lk(mtx_);
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if (closed(lk)) BOOST_THROW_EXCEPTION( sync_queue_is_closed() );
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fut_ = fut_.then(ex_, continuation(work(closure)));
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}
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#endif
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void submit(void (*closure)())
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{
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lock_guard<mutex> lk(mtx_);
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if (closed(lk)) BOOST_THROW_EXCEPTION( sync_queue_is_closed() );
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fut_ = fut_.then(ex_, continuation(work(closure)));
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}
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template <typename Closure>
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void submit(BOOST_THREAD_FWD_REF(Closure) closure)
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{
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lock_guard<mutex> lk(mtx_);
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if (closed(lk)) BOOST_THROW_EXCEPTION( sync_queue_is_closed() );
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fut_ = fut_.then(ex_, continuation(work(boost::forward<Closure>(closure))));
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}
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};
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}
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using executors::serial_executor_cont;
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}
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#include <boost/config/abi_suffix.hpp>
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#endif
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#endif
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