summaryrefslogtreecommitdiffstatshomepage
path: root/3rdparty/asio/src/examples/cpp11/fork/process_per_connection.cpp
diff options
context:
space:
mode:
Diffstat (limited to '3rdparty/asio/src/examples/cpp11/fork/process_per_connection.cpp')
-rw-r--r--3rdparty/asio/src/examples/cpp11/fork/process_per_connection.cpp162
1 files changed, 162 insertions, 0 deletions
diff --git a/3rdparty/asio/src/examples/cpp11/fork/process_per_connection.cpp b/3rdparty/asio/src/examples/cpp11/fork/process_per_connection.cpp
new file mode 100644
index 00000000000..217d5d945ae
--- /dev/null
+++ b/3rdparty/asio/src/examples/cpp11/fork/process_per_connection.cpp
@@ -0,0 +1,162 @@
+//
+// process_per_connection.cpp
+// ~~~~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 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 <asio/io_context.hpp>
+#include <asio/ip/tcp.hpp>
+#include <asio/signal_set.hpp>
+#include <asio/write.hpp>
+#include <cstdlib>
+#include <iostream>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+using asio::ip::tcp;
+
+class server
+{
+public:
+ server(asio::io_context& io_context, unsigned short port)
+ : io_context_(io_context),
+ signal_(io_context, SIGCHLD),
+ acceptor_(io_context, {tcp::v4(), port}),
+ socket_(io_context)
+ {
+ wait_for_signal();
+ accept();
+ }
+
+private:
+ void wait_for_signal()
+ {
+ signal_.async_wait(
+ [this](std::error_code /*ec*/, int /*signo*/)
+ {
+ // Only the parent process should check for this signal. We can
+ // determine whether we are in the parent by checking if the acceptor
+ // is still open.
+ if (acceptor_.is_open())
+ {
+ // Reap completed child processes so that we don't end up with
+ // zombies.
+ int status = 0;
+ while (waitpid(-1, &status, WNOHANG) > 0) {}
+
+ wait_for_signal();
+ }
+ });
+ }
+
+ void accept()
+ {
+ acceptor_.async_accept(
+ [this](std::error_code ec, tcp::socket new_socket)
+ {
+ if (!ec)
+ {
+ // Take ownership of the newly accepted socket.
+ socket_ = std::move(new_socket);
+
+ // Inform the io_context that we are about to fork. The io_context
+ // cleans up any internal resources, such as threads, that may
+ // interfere with forking.
+ io_context_.notify_fork(asio::io_context::fork_prepare);
+
+ if (fork() == 0)
+ {
+ // Inform the io_context that the fork is finished and that this
+ // is the child process. The io_context uses this opportunity to
+ // create any internal file descriptors that must be private to
+ // the new process.
+ io_context_.notify_fork(asio::io_context::fork_child);
+
+ // The child won't be accepting new connections, so we can close
+ // the acceptor. It remains open in the parent.
+ acceptor_.close();
+
+ // The child process is not interested in processing the SIGCHLD
+ // signal.
+ signal_.cancel();
+
+ read();
+ }
+ else
+ {
+
+ // Inform the io_context that the fork is finished (or failed)
+ // and that this is the parent process. The io_context uses this
+ // opportunity to recreate any internal resources that were
+ // cleaned up during preparation for the fork.
+ io_context_.notify_fork(asio::io_context::fork_parent);
+
+ // The parent process can now close the newly accepted socket. It
+ // remains open in the child.
+ socket_.close();
+
+ accept();
+ }
+ }
+ else
+ {
+ std::cerr << "Accept error: " << ec.message() << std::endl;
+ accept();
+ }
+ });
+ }
+
+ void read()
+ {
+ socket_.async_read_some(asio::buffer(data_),
+ [this](std::error_code ec, std::size_t length)
+ {
+ if (!ec)
+ write(length);
+ });
+ }
+
+ void write(std::size_t length)
+ {
+ asio::async_write(socket_, asio::buffer(data_, length),
+ [this](std::error_code ec, std::size_t /*length*/)
+ {
+ if (!ec)
+ read();
+ });
+ }
+
+ asio::io_context& io_context_;
+ asio::signal_set signal_;
+ tcp::acceptor acceptor_;
+ tcp::socket socket_;
+ std::array<char, 1024> data_;
+};
+
+int main(int argc, char* argv[])
+{
+ try
+ {
+ if (argc != 2)
+ {
+ std::cerr << "Usage: process_per_connection <port>\n";
+ return 1;
+ }
+
+ asio::io_context io_context;
+
+ using namespace std; // For atoi.
+ server s(io_context, atoi(argv[1]));
+
+ io_context.run();
+ }
+ catch (std::exception& e)
+ {
+ std::cerr << "Exception: " << e.what() << std::endl;
+ }
+}