1 //
2 // io_context_pool.cpp
3 // ~~~~~~~~~~~~~~~~~~~
4 //
5 // Copyright (c) 2003-2019 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 #include "server.hpp"
12 #include <stdexcept>
13 #include <boost/thread/thread.hpp>
14 #include <boost/bind.hpp>
15 #include <boost/shared_ptr.hpp>
16 
17 namespace http {
18 namespace server2 {
19 
io_context_pool(std::size_t pool_size)20 io_context_pool::io_context_pool(std::size_t pool_size)
21   : next_io_context_(0)
22 {
23   if (pool_size == 0)
24     throw std::runtime_error("io_context_pool size is 0");
25 
26   // Give all the io_contexts work to do so that their run() functions will not
27   // exit until they are explicitly stopped.
28   for (std::size_t i = 0; i < pool_size; ++i)
29   {
30     io_context_ptr io_context(new boost::asio::io_context);
31     io_contexts_.push_back(io_context);
32     work_.push_back(boost::asio::make_work_guard(*io_context));
33   }
34 }
35 
run()36 void io_context_pool::run()
37 {
38   // Create a pool of threads to run all of the io_contexts.
39   std::vector<boost::shared_ptr<boost::thread> > threads;
40   for (std::size_t i = 0; i < io_contexts_.size(); ++i)
41   {
42     boost::shared_ptr<boost::thread> thread(new boost::thread(
43           boost::bind(&boost::asio::io_context::run, io_contexts_[i])));
44     threads.push_back(thread);
45   }
46 
47   // Wait for all threads in the pool to exit.
48   for (std::size_t i = 0; i < threads.size(); ++i)
49     threads[i]->join();
50 }
51 
stop()52 void io_context_pool::stop()
53 {
54   // Explicitly stop all io_contexts.
55   for (std::size_t i = 0; i < io_contexts_.size(); ++i)
56     io_contexts_[i]->stop();
57 }
58 
get_io_context()59 boost::asio::io_context& io_context_pool::get_io_context()
60 {
61   // Use a round-robin scheme to choose the next io_context to use.
62   boost::asio::io_context& io_context = *io_contexts_[next_io_context_];
63   ++next_io_context_;
64   if (next_io_context_ == io_contexts_.size())
65     next_io_context_ = 0;
66   return io_context;
67 }
68 
69 } // namespace server2
70 } // namespace http
71