asio/impl/thread_pool.ipp

0001 //
0002 // impl/thread_pool.ipp
0003 // ~~~~~~~~~~~~~~~~~~~~
0004 //
0005 // Copyright (c) 2003-2025 Christopher M. Kohlhoff (chris at kohlhoff dot com)
0006 //
0007 // Distributed under the Boost Software License, Version 1.0. (See accompanying
0008 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
0009 //
0010
0011 #ifndef BOOST_ASIO_IMPL_THREAD_POOL_IPP
0012 #define BOOST_ASIO_IMPL_THREAD_POOL_IPP
0013
0014 #if defined(_MSC_VER) && (_MSC_VER >= 1200)
0015 # pragma once
0016 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
0017
0018 #include <boost/asio/detail/config.hpp>
0019 #include <stdexcept>
0020 #include <boost/asio/thread_pool.hpp>
0021 #include <boost/asio/detail/throw_exception.hpp>
0022
0023 #include <boost/asio/detail/push_options.hpp>
0024
0025 namespace boost {
0026 namespace asio {
0027
0028 struct thread_pool::thread_function
0029 {
0030   detail::scheduler* scheduler_;
0031
0032   void operator()()
0033   {
0034 #if !defined(BOOST_ASIO_NO_EXCEPTIONS)
0035     try
0036     {
0037 #endif// !defined(BOOST_ASIO_NO_EXCEPTIONS)
0038       boost::system::error_code ec;
0039       scheduler_->run(ec);
0040 #if !defined(BOOST_ASIO_NO_EXCEPTIONS)
0041     }
0042     catch (...)
0043     {
0044       std::terminate();
0045     }
0046 #endif// !defined(BOOST_ASIO_NO_EXCEPTIONS)
0047   }
0048 };
0049
0050 #if !defined(BOOST_ASIO_NO_TS_EXECUTORS)
0051 namespace detail {
0052
0053 inline long default_thread_pool_size()
0054 {
0055   std::size_t num_threads = thread::hardware_concurrency() * 2;
0056   num_threads = num_threads == 0 ? 2 : num_threads;
0057   return static_cast<long>(num_threads);
0058 }
0059
0060 } // namespace detail
0061
0062 thread_pool::thread_pool()
0063   : scheduler_(add_scheduler(new detail::scheduler(*this, false))),
0064     num_threads_(detail::default_thread_pool_size()),
0065     joinable_(true)
0066 {
0067   scheduler_.work_started();
0068
0069   thread_function f = { &scheduler_ };
0070   threads_.create_threads(f, static_cast<std::size_t>(num_threads_));
0071 }
0072 #endif // !defined(BOOST_ASIO_NO_TS_EXECUTORS)
0073
0074 namespace detail {
0075
0076 inline long clamp_thread_pool_size(std::size_t n)
0077 {
0078   if (n > 0x7FFFFFFF)
0079   {
0080     std::out_of_range ex("thread pool size");
0081     boost::asio::detail::throw_exception(ex);
0082   }
0083   return static_cast<long>(n & 0x7FFFFFFF);
0084 }
0085
0086 } // namespace detail
0087
0088 thread_pool::thread_pool(std::size_t num_threads)
0089   : execution_context(config_from_concurrency_hint(num_threads == 1 ? 1 : 0)),
0090     scheduler_(add_scheduler(new detail::scheduler(*this, false))),
0091     num_threads_(detail::clamp_thread_pool_size(num_threads)),
0092     joinable_(true)
0093 {
0094   scheduler_.work_started();
0095
0096   thread_function f = { &scheduler_ };
0097   threads_.create_threads(f, static_cast<std::size_t>(num_threads_));
0098 }
0099
0100 thread_pool::thread_pool(std::size_t num_threads,
0101     const execution_context::service_maker& initial_services)
0102   : execution_context(initial_services),
0103     scheduler_(add_scheduler(new detail::scheduler(*this, false))),
0104     num_threads_(detail::clamp_thread_pool_size(num_threads)),
0105     joinable_(true)
0106 {
0107   scheduler_.work_started();
0108
0109   thread_function f = { &scheduler_ };
0110   threads_.create_threads(f, static_cast<std::size_t>(num_threads_));
0111 }
0112
0113 thread_pool::~thread_pool()
0114 {
0115   stop();
0116   join();
0117   shutdown();
0118 }
0119
0120 void thread_pool::stop()
0121 {
0122   scheduler_.stop();
0123 }
0124
0125 void thread_pool::attach()
0126 {
0127   ++num_threads_;
0128   thread_function f = { &scheduler_ };
0129   f();
0130 }
0131
0132 void thread_pool::join()
0133 {
0134   if (joinable_)
0135   {
0136     joinable_ = false;
0137     scheduler_.work_finished();
0138     threads_.join();
0139   }
0140 }
0141
0142 detail::scheduler& thread_pool::add_scheduler(detail::scheduler* s)
0143 {
0144   detail::scoped_ptr<detail::scheduler> scoped_impl(s);
0145   boost::asio::add_service<detail::scheduler>(*this, scoped_impl.get());
0146   return *scoped_impl.release();
0147 }
0148
0149 void thread_pool::wait()
0150 {
0151   join();
0152 }
0153
0154 } // namespace asio
0155 } // namespace boost
0156
0157 #include <boost/asio/detail/pop_options.hpp>
0158
0159 #endif // BOOST_ASIO_IMPL_THREAD_POOL_IPP