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1//
2// impl/thread_pool.ipp
3// ~~~~~~~~~~~~~~~~~~~~
4//
5// Copyright (c) 2003-2020 Christopher M. Kohlhoff (chris at kohlhoff dot com)
6//
7// Distributed under the Boost Software License, Version 1.0. (See accompanying
8// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
9//
10
11#ifndef BOOST_ASIO_IMPL_THREAD_POOL_IPP
12#define BOOST_ASIO_IMPL_THREAD_POOL_IPP
13
14#if defined(_MSC_VER) && (_MSC_VER >= 1200)
15# pragma once
16#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
17
18#include <boost/asio/detail/config.hpp>
19#include <stdexcept>
20#include <boost/asio/thread_pool.hpp>
21#include <boost/asio/detail/throw_exception.hpp>
22
23#include <boost/asio/detail/push_options.hpp>
24
25namespace boost {
26namespace asio {
27
28struct thread_pool::thread_function
29{
30  detail::scheduler* scheduler_;
31
32  void operator()()
33  {
34#if !defined(BOOST_ASIO_NO_EXCEPTIONS)
35    try
36    {
37#endif// !defined(BOOST_ASIO_NO_EXCEPTIONS)
38      boost::system::error_code ec;
39      scheduler_->run(ec);
40#if !defined(BOOST_ASIO_NO_EXCEPTIONS)
41    }
42    catch (...)
43    {
44      std::terminate();
45    }
46#endif// !defined(BOOST_ASIO_NO_EXCEPTIONS)
47  }
48};
49
50#if !defined(BOOST_ASIO_NO_TS_EXECUTORS)
51namespace detail {
52
53inline long default_thread_pool_size()
54{
55  std::size_t num_threads = thread::hardware_concurrency() * 2;
56  num_threads = num_threads == 0 ? 2 : num_threads;
57  return static_cast<long>(num_threads);
58}
59
60} // namespace detail
61
62thread_pool::thread_pool()
63  : scheduler_(add_scheduler(new detail::scheduler(*this, 0, false))),
64    num_threads_(detail::default_thread_pool_size())
65{
66  scheduler_.work_started();
67
68  thread_function f = { &scheduler_ };
69  threads_.create_threads(f, static_cast<std::size_t>(num_threads_));
70}
71#endif // !defined(BOOST_ASIO_NO_TS_EXECUTORS)
72
73namespace detail {
74
75inline long clamp_thread_pool_size(std::size_t n)
76{
77  if (n > 0x7FFFFFFF)
78  {
79    std::out_of_range ex("thread pool size");
80    boost::asio::detail::throw_exception(ex);
81  }
82  return static_cast<long>(n & 0x7FFFFFFF);
83}
84
85} // namespace detail
86
87thread_pool::thread_pool(std::size_t num_threads)
88  : scheduler_(add_scheduler(new detail::scheduler(
89          *this, num_threads == 1 ? 1 : 0, false))),
90    num_threads_(detail::clamp_thread_pool_size(num_threads))
91{
92  scheduler_.work_started();
93
94  thread_function f = { &scheduler_ };
95  threads_.create_threads(f, static_cast<std::size_t>(num_threads_));
96}
97
98thread_pool::~thread_pool()
99{
100  stop();
101  join();
102}
103
104void thread_pool::stop()
105{
106  scheduler_.stop();
107}
108
109void thread_pool::attach()
110{
111  ++num_threads_;
112  thread_function f = { &scheduler_ };
113  f();
114}
115
116void thread_pool::join()
117{
118  if (!threads_.empty())
119  {
120    scheduler_.work_finished();
121    threads_.join();
122  }
123}
124
125detail::scheduler& thread_pool::add_scheduler(detail::scheduler* s)
126{
127  detail::scoped_ptr<detail::scheduler> scoped_impl(s);
128  boost::asio::add_service<detail::scheduler>(*this, scoped_impl.get());
129  return *scoped_impl.release();
130}
131
132void thread_pool::wait()
133{
134  scheduler_.work_finished();
135  threads_.join();
136}
137
138} // namespace asio
139} // namespace boost
140
141#include <boost/asio/detail/pop_options.hpp>
142
143#endif // BOOST_ASIO_IMPL_THREAD_POOL_IPP
144