Initial Commit

include/asio/impl/thread_pool.ipp

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+//
+// impl/thread_pool.ipp
+// ~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2025 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// 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)
+//
+
+#ifndef ASIO_IMPL_THREAD_POOL_IPP
+#define ASIO_IMPL_THREAD_POOL_IPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include "asio/detail/config.hpp"
+#include <stdexcept>
+#include "asio/thread_pool.hpp"
+#include "asio/detail/throw_exception.hpp"
+
+#include "asio/detail/push_options.hpp"
+
+namespace asio {
+
+struct thread_pool::thread_function
+{
+  detail::scheduler* scheduler_;
+
+  void operator()()
+  {
+#if !defined(ASIO_NO_EXCEPTIONS)
+    try
+    {
+#endif// !defined(ASIO_NO_EXCEPTIONS)
+      asio::error_code ec;
+      scheduler_->run(ec);
+#if !defined(ASIO_NO_EXCEPTIONS)
+    }
+    catch (...)
+    {
+      std::terminate();
+    }
+#endif// !defined(ASIO_NO_EXCEPTIONS)
+  }
+};
+
+#if !defined(ASIO_NO_TS_EXECUTORS)
+
+long thread_pool::default_thread_pool_size()
+{
+  std::size_t num_threads = detail::thread::hardware_concurrency() * 2;
+  num_threads = num_threads == 0 ? 2 : num_threads;
+  return static_cast<long>(num_threads);
+}
+
+thread_pool::thread_pool()
+  : scheduler_(asio::make_service<detail::scheduler>(*this, false)),
+    threads_(allocator<void>(*this)),
+    num_threads_(default_thread_pool_size()),
+    joinable_(true)
+{
+  start();
+}
+
+#endif // !defined(ASIO_NO_TS_EXECUTORS)
+
+long thread_pool::clamp_thread_pool_size(std::size_t n)
+{
+  if (n > 0x7FFFFFFF)
+  {
+    std::out_of_range ex("thread pool size");
+    asio::detail::throw_exception(ex);
+  }
+  return static_cast<long>(n & 0x7FFFFFFF);
+}
+
+thread_pool::thread_pool(std::size_t num_threads)
+  : execution_context(config_from_concurrency_hint(num_threads == 1 ? 1 : 0)),
+    scheduler_(asio::make_service<detail::scheduler>(*this, false)),
+    threads_(allocator<void>(*this)),
+    num_threads_(clamp_thread_pool_size(num_threads)),
+    joinable_(true)
+{
+  start();
+}
+
+thread_pool::thread_pool(std::size_t num_threads,
+    const execution_context::service_maker& initial_services)
+  : execution_context(initial_services),
+    scheduler_(asio::make_service<detail::scheduler>(*this, false)),
+    threads_(allocator<void>(*this)),
+    num_threads_(clamp_thread_pool_size(num_threads)),
+    joinable_(true)
+{
+  start();
+}
+
+thread_pool::~thread_pool()
+{
+  stop();
+  join();
+  shutdown();
+}
+
+void thread_pool::start()
+{
+  scheduler_.work_started();
+  thread_function f = { &scheduler_ };
+  threads_.create_threads(f, static_cast<std::size_t>(num_threads_));
+}
+
+void thread_pool::stop()
+{
+  scheduler_.stop();
+}
+
+void thread_pool::attach()
+{
+  ++num_threads_;
+  thread_function f = { &scheduler_ };
+  f();
+}
+
+void thread_pool::join()
+{
+  if (joinable_)
+  {
+    joinable_ = false;
+    scheduler_.work_finished();
+    threads_.join();
+  }
+}
+
+void thread_pool::wait()
+{
+  join();
+}
+
+} // namespace asio
+
+#include "asio/detail/pop_options.hpp"
+
+#endif // ASIO_IMPL_THREAD_POOL_IPP