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doc/html/boost_asio/example/cpp11/http/server3/server.cpp

//
// server.cpp
// ~~~~~~~~~~
//
// Copyright (c) 2003-2024 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)
//

#include "server.hpp"
#include <signal.h>
#include <thread>
#include <utility>
#include <vector>
#include "connection.hpp"

namespace http {
namespace server3 {

server::server(const std::string& address, const std::string& port,
    const std::string& doc_root, std::size_t thread_pool_size)
  : thread_pool_size_(thread_pool_size),
    signals_(io_context_),
    acceptor_(io_context_),
    request_handler_(doc_root)
{
  // Register to handle the signals that indicate when the server should exit.
  // It is safe to register for the same signal multiple times in a program,
  // provided all registration for the specified signal is made through Asio.
  signals_.add(SIGINT);
  signals_.add(SIGTERM);
#if defined(SIGQUIT)
  signals_.add(SIGQUIT);
#endif // defined(SIGQUIT)

  do_await_stop();

  // Open the acceptor with the option to reuse the address (i.e. SO_REUSEADDR).
  boost::asio::ip::tcp::resolver resolver(io_context_);
  boost::asio::ip::tcp::endpoint endpoint =
    *resolver.resolve(address, port).begin();
  acceptor_.open(endpoint.protocol());
  acceptor_.set_option(boost::asio::ip::tcp::acceptor::reuse_address(true));
  acceptor_.bind(endpoint);
  acceptor_.listen();

  do_accept();
}

void server::run()
{
  // Create a pool of threads to run the io_context.
  std::vector<std::thread> threads;
  for (std::size_t i = 0; i < thread_pool_size_; ++i)
    threads.emplace_back([this]{ io_context_.run(); });

  // Wait for all threads in the pool to exit.
  for (std::size_t i = 0; i < threads.size(); ++i)
    threads[i].join();
}

void server::do_accept()
{
  // The newly accepted socket is put into its own strand to ensure that all
  // completion handlers associated with the connection do not run concurrently.
  acceptor_.async_accept(boost::asio::make_strand(io_context_),
      [this](boost::system::error_code ec, boost::asio::ip::tcp::socket socket)
      {
        // Check whether the server was stopped by a signal before this
        // completion handler had a chance to run.
        if (!acceptor_.is_open())
        {
          return;
        }

        if (!ec)
        {
          std::make_shared<connection>(
              std::move(socket), request_handler_)->start();
        }

        do_accept();
      });
}

void server::do_await_stop()
{
  signals_.async_wait(
      [this](boost::system::error_code /*ec*/, int /*signo*/)
      {
        io_context_.stop();
      });
}

} // namespace server3
} // namespace http