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Diffstat (limited to '3rdparty/asio/src/examples/cpp03/timeouts/async_tcp_client.cpp')
-rw-r--r-- | 3rdparty/asio/src/examples/cpp03/timeouts/async_tcp_client.cpp | 308 |
1 files changed, 308 insertions, 0 deletions
diff --git a/3rdparty/asio/src/examples/cpp03/timeouts/async_tcp_client.cpp b/3rdparty/asio/src/examples/cpp03/timeouts/async_tcp_client.cpp new file mode 100644 index 00000000000..98b90e9a1b3 --- /dev/null +++ b/3rdparty/asio/src/examples/cpp03/timeouts/async_tcp_client.cpp @@ -0,0 +1,308 @@ +// +// async_tcp_client.cpp +// ~~~~~~~~~~~~~~~~~~~~ +// +// Copyright (c) 2003-2016 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/deadline_timer.hpp" +#include "asio/io_context.hpp" +#include "asio/ip/tcp.hpp" +#include "asio/read_until.hpp" +#include "asio/streambuf.hpp" +#include "asio/write.hpp" +#include <boost/bind.hpp> +#include <iostream> + +using asio::deadline_timer; +using asio::ip::tcp; + +// +// This class manages socket timeouts by applying the concept of a deadline. +// Some asynchronous operations are given deadlines by which they must complete. +// Deadlines are enforced by an "actor" that persists for the lifetime of the +// client object: +// +// +----------------+ +// | | +// | check_deadline |<---+ +// | | | +// +----------------+ | async_wait() +// | | +// +---------+ +// +// If the deadline actor determines that the deadline has expired, the socket +// is closed and any outstanding operations are consequently cancelled. +// +// Connection establishment involves trying each endpoint in turn until a +// connection is successful, or the available endpoints are exhausted. If the +// deadline actor closes the socket, the connect actor is woken up and moves to +// the next endpoint. +// +// +---------------+ +// | | +// | start_connect |<---+ +// | | | +// +---------------+ | +// | | +// async_- | +----------------+ +// connect() | | | +// +--->| handle_connect | +// | | +// +----------------+ +// : +// Once a connection is : +// made, the connect : +// actor forks in two - : +// : +// an actor for reading : and an actor for +// inbound messages: : sending heartbeats: +// : +// +------------+ : +-------------+ +// | |<- - - - -+- - - - ->| | +// | start_read | | start_write |<---+ +// | |<---+ | | | +// +------------+ | +-------------+ | async_wait() +// | | | | +// async_- | +-------------+ async_- | +--------------+ +// read_- | | | write() | | | +// until() +--->| handle_read | +--->| handle_write | +// | | | | +// +-------------+ +--------------+ +// +// The input actor reads messages from the socket, where messages are delimited +// by the newline character. The deadline for a complete message is 30 seconds. +// +// The heartbeat actor sends a heartbeat (a message that consists of a single +// newline character) every 10 seconds. In this example, no deadline is applied +// message sending. +// +class client +{ +public: + client(asio::io_context& io_context) + : stopped_(false), + socket_(io_context), + deadline_(io_context), + heartbeat_timer_(io_context) + { + } + + // Called by the user of the client class to initiate the connection process. + // The endpoints will have been obtained using a tcp::resolver. + void start(tcp::resolver::results_type endpoints) + { + // Start the connect actor. + endpoints_ = endpoints; + start_connect(endpoints_.begin()); + + // Start the deadline actor. You will note that we're not setting any + // particular deadline here. Instead, the connect and input actors will + // update the deadline prior to each asynchronous operation. + deadline_.async_wait(boost::bind(&client::check_deadline, this)); + } + + // This function terminates all the actors to shut down the connection. It + // may be called by the user of the client class, or by the class itself in + // response to graceful termination or an unrecoverable error. + void stop() + { + stopped_ = true; + asio::error_code ignored_ec; + socket_.close(ignored_ec); + deadline_.cancel(); + heartbeat_timer_.cancel(); + } + +private: + void start_connect(tcp::resolver::results_type::iterator endpoint_iter) + { + if (endpoint_iter != endpoints_.end()) + { + std::cout << "Trying " << endpoint_iter->endpoint() << "...\n"; + + // Set a deadline for the connect operation. + deadline_.expires_from_now(boost::posix_time::seconds(60)); + + // Start the asynchronous connect operation. + socket_.async_connect(endpoint_iter->endpoint(), + boost::bind(&client::handle_connect, + this, _1, endpoint_iter)); + } + else + { + // There are no more endpoints to try. Shut down the client. + stop(); + } + } + + void handle_connect(const asio::error_code& ec, + tcp::resolver::results_type::iterator endpoint_iter) + { + if (stopped_) + return; + + // The async_connect() function automatically opens the socket at the start + // of the asynchronous operation. If the socket is closed at this time then + // the timeout handler must have run first. + if (!socket_.is_open()) + { + std::cout << "Connect timed out\n"; + + // Try the next available endpoint. + start_connect(++endpoint_iter); + } + + // Check if the connect operation failed before the deadline expired. + else if (ec) + { + std::cout << "Connect error: " << ec.message() << "\n"; + + // We need to close the socket used in the previous connection attempt + // before starting a new one. + socket_.close(); + + // Try the next available endpoint. + start_connect(++endpoint_iter); + } + + // Otherwise we have successfully established a connection. + else + { + std::cout << "Connected to " << endpoint_iter->endpoint() << "\n"; + + // Start the input actor. + start_read(); + + // Start the heartbeat actor. + start_write(); + } + } + + void start_read() + { + // Set a deadline for the read operation. + deadline_.expires_from_now(boost::posix_time::seconds(30)); + + // Start an asynchronous operation to read a newline-delimited message. + asio::async_read_until(socket_, input_buffer_, '\n', + boost::bind(&client::handle_read, this, _1)); + } + + void handle_read(const asio::error_code& ec) + { + if (stopped_) + return; + + if (!ec) + { + // Extract the newline-delimited message from the buffer. + std::string line; + std::istream is(&input_buffer_); + std::getline(is, line); + + // Empty messages are heartbeats and so ignored. + if (!line.empty()) + { + std::cout << "Received: " << line << "\n"; + } + + start_read(); + } + else + { + std::cout << "Error on receive: " << ec.message() << "\n"; + + stop(); + } + } + + void start_write() + { + if (stopped_) + return; + + // Start an asynchronous operation to send a heartbeat message. + asio::async_write(socket_, asio::buffer("\n", 1), + boost::bind(&client::handle_write, this, _1)); + } + + void handle_write(const asio::error_code& ec) + { + if (stopped_) + return; + + if (!ec) + { + // Wait 10 seconds before sending the next heartbeat. + heartbeat_timer_.expires_from_now(boost::posix_time::seconds(10)); + heartbeat_timer_.async_wait(boost::bind(&client::start_write, this)); + } + else + { + std::cout << "Error on heartbeat: " << ec.message() << "\n"; + + stop(); + } + } + + void check_deadline() + { + if (stopped_) + return; + + // Check whether the deadline has passed. We compare the deadline against + // the current time since a new asynchronous operation may have moved the + // deadline before this actor had a chance to run. + if (deadline_.expires_at() <= deadline_timer::traits_type::now()) + { + // The deadline has passed. The socket is closed so that any outstanding + // asynchronous operations are cancelled. + socket_.close(); + + // There is no longer an active deadline. The expiry is set to positive + // infinity so that the actor takes no action until a new deadline is set. + deadline_.expires_at(boost::posix_time::pos_infin); + } + + // Put the actor back to sleep. + deadline_.async_wait(boost::bind(&client::check_deadline, this)); + } + +private: + bool stopped_; + tcp::resolver::results_type endpoints_; + tcp::socket socket_; + asio::streambuf input_buffer_; + deadline_timer deadline_; + deadline_timer heartbeat_timer_; +}; + +int main(int argc, char* argv[]) +{ + try + { + if (argc != 3) + { + std::cerr << "Usage: client <host> <port>\n"; + return 1; + } + + asio::io_context io_context; + tcp::resolver r(io_context); + client c(io_context); + + c.start(r.resolve(argv[1], argv[2])); + + io_context.run(); + } + catch (std::exception& e) + { + std::cerr << "Exception: " << e.what() << "\n"; + } + + return 0; +} |