如何模拟带有超时的boost :: asio :: write [英] How to simulate boost::asio::write with a timeout
问题描述
我正在尝试模拟超时的boost::asio::write.或者您可以说，我正在尝试将boost::asio::async_write与超时一起使用.
I am trying to simulate boost::asio::write with timeout. Or you can say, I am trying to use boost::asio::async_write with a timeout.
如我所见，boost::asio::write会阻塞，直到所有数据已被写入和写入为止.阅读.这种功能当然需要超时.
As I see, boost::asio::write blocks until all data has been written & read on the other side. This kind of functionality certainly requires a timeout.
所以，通过阅读这里的简单答案罗伯特·海格纳(Robert Hegner)演示了如何使用 timeout 来执行boost::asio::async_read，我正在尝试通过修改来适应相同的写逻辑:
So, Reading through this simple answer here by Robert Hegner which demostrates how to do a boost::asio::async_read with timeout, I am trying adapt the same logic for write by doing so:
size_t write_data_with_time_out() {
long time_out_secs = 2;
boost::optional<boost::system::error_code> timer_result;
boost::asio::deadline_timer timer(the_socket->get_io_service(), boost::posix_time::seconds(time_out_secs));
timer.expires_from_now();
timer.async_wait([&timer_result] (const boost::system::error_code& error) {
timer_result.reset(error);
});
boost::optional<boost::system::error_code> write_result;
size_t bytes_sent = 0;
boost::asio::async_write(*the_socket, boost::asio::buffer(the_buffer_to_write, the_buffer_to_write.size()), [&write_result, &bytes_sent] (const boost::system::error_code& error, auto size_received) {
write_result.reset(error);
bytes_sent = size_received;
});
the_socket->get_io_service().reset();
while (the_socket->get_io_service().run_one()) {
if (write_result) {
timer.cancel();
}
else if (timer_result) {
the_socket->cancel();
}
}
if (*write_result) {
return 0;
}
return bytes_sent;
}
问题:
该逻辑对于读取非常有用，但对于强写情况似乎不起作用. 原因是while (the_socket->get_io_service().run_one())在两次调用the_socket->cancel()之后被挂起.
Problem:
The logic works great for read but does not seem to work for write case. Reason is that while (the_socket->get_io_service().run_one()) gets hung after calling the_socket->cancel() twice.
，在阅读情况下，the_socket->cancel()也被称为两次& ;；不会挂在while&的第3个循环上返回.因此，阅读没有问题.
However, in the read case also the_socket->cancel() is called twice & does not hang on the 3rd loop over of the while & returns out. Hence no issues with read.
问题:
我的理解是否错误，因为相同的超时逻辑适用于boost::asio::async_write情况?我认为同样的逻辑应该起作用.我正在做某事，这是我需要提出的建议.
Question:
Is my understanding wrong that same timeout logic would work for boost::asio::async_write case? I think this same logic should work. There is something wrong I am doing which is what I need a suggestion on.
可能的话，还需要其他信息:
如果boost::asio::read& boost::asio::write具有超时参数.我不会写多余的东西.似乎已经有很多要求asio的人在他们的同步读取&中引入超时的要求.写函数.就像这里的这个一样.
是否有asio专家可以在不久的将来解决此请求?
Additional info required if possible:
if boost::asio::read & boost::asio::write had a timeout parameter. I would not have been writing this extra. Seems like there have been a lot of requests to asio guys to introduce a timeout in their sync read & write functions. Like this one here.
Is there any scope for asio guys to address this request in near future?
我正在执行同步boost::asio::read& boost::asio::write在同一套接字上使用工作线程非常出色.我所缺少的只是此超时功能.
I am doing a sync boost::asio::read & boost::asio::write on the same socket using a worker thread for which this works superb. All I am missing is this timeout functionality.
环境:
我的代码在Linux& MacOSX与C ++ 14编译器一起使用.这个问题只涉及 TCP套接字.
Environment:
My code runs on Linux & MacOSX with C++ 14 compiler. This question only concerns TCP sockets.
推荐答案
我编写了以下帮助程序，以与超时同步地同步任何异步操作¹:
I've written the following helper to await any async operation synchronously with a timeout¹:
template<typename AllowTime> void await_operation(AllowTime const& deadline_or_duration) {
using namespace boost::asio;
ioservice.reset();
{
high_resolution_timer tm(ioservice, deadline_or_duration);
tm.async_wait([this](error_code ec) { if (ec != error::operation_aborted) socket.cancel(); });
ioservice.run_one();
}
ioservice.run();
}
此后，我还在完整的TCP客户端上进行了演示: Boost ::具有超时的Asio同步客户端
I've since also demoed that with a full on TCP client: Boost::Asio synchronous client with timeout
该示例包括写入操作，并且已经过全面测试.
The sample includes write operations and has been completely tested.
以原始文章中的更精细"示例为例(FTP客户端示例显示了更实际的使用模式):
Taking the "nicer" example from the original post (the FTP client example shows more realistic usage patterns):
#ifndef __TCPCLIENT_H__
#define __TCPCLIENT_H__
#include <boost/asio.hpp>
#include <boost/asio/high_resolution_timer.hpp>
#include <iostream>
class TCPClient {
public:
void disconnect();
void connect(const std::string& address, const std::string& port);
std::string sendMessage(const std::string& msg);
private:
using error_code = boost::system::error_code;
template<typename AllowTime> void await_operation(AllowTime const& deadline_or_duration) {
using namespace boost::asio;
ioservice.reset();
{
high_resolution_timer tm(ioservice, deadline_or_duration);
tm.async_wait([this](error_code ec) { if (ec != error::operation_aborted) socket.cancel(); });
ioservice.run_one();
}
ioservice.run();
}
struct raise {
template <typename... A> void operator()(error_code ec, A...) const {
if (ec) throw std::runtime_error(ec.message());
}
};
boost::asio::io_service ioservice { };
boost::asio::ip::tcp::socket socket { ioservice };
};
inline void TCPClient::disconnect() {
using namespace boost::asio;
if (socket.is_open()) {
try {
socket.shutdown(ip::tcp::socket::shutdown_both);
socket.close();
}
catch (const boost::system::system_error& e) {
// ignore
std::cerr << "ignored error " << e.what() << std::endl;
}
}
}
inline void TCPClient::connect(const std::string& address, const std::string& port) {
using namespace boost::asio;
async_connect(socket, ip::tcp::resolver(ioservice).resolve({address, port}), raise());
await_operation(std::chrono::seconds(6));
}
inline std::string TCPClient::sendMessage(const std::string& msg) {
using namespace boost::asio;
streambuf response;
async_read_until(socket, response, '\n', raise());
await_operation(std::chrono::system_clock::now() + std::chrono::seconds(4));
return {std::istreambuf_iterator<char>(&response), {}};
}
#endif
#include <iostream>
//#include "TCPClient.hpp"
int main(/*int argc, char* argv[]*/) {
TCPClient client;
try {
client.connect("127.0.0.1", "27015");
std::cout << "Response: " << client.sendMessage("Hello!") << std::endl;
}
catch (const boost::system::system_error& e) {
std::cerr << e.what() << std::endl;
}
catch (const std::exception& e) {
std::cerr << e.what() << std::endl;
}
}
¹最初是为该答案而写的 https://stackoverflow.com/a/33445833/85371
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