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c++ - UDP Boost ASIO 异步客户端挂起

转载 作者:搜寻专家 更新时间:2023-10-31 01:13:21 25 4
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我正在尝试使用 boost asio 制作一个玩具异步回显客户端。由于某种原因,它在等待 sent_=true 时在第二个请求/回复周期被阻塞,但在接收回显之前(没有服务器崩溃)。

/*
UDP asynchronous clint using boost asio library
*/
#include <cstdlib>
#include <iostream>
#include <algorithm>

#include <boost/array.hpp>
#include <boost/asio.hpp>
#include <boost/lexical_cast.hpp>
#include <boost/thread.hpp>
#include <boost/bind.hpp>
#include <boost/chrono/duration.hpp>

#include "dbook/test/tools.hpp"

using boost::asio::ip::udp;

const size_t N_MESSAGES = 1024;

class udp_client {
public:
udp_client(const std::string& host,const std::string& service)
:io_service_(),
socket_(io_service_),
replied_(false),
sent_(false)
{
socket_.open(boost::asio::ip::udp::v4());
udp::resolver resolver(io_service_);
udp::resolver::query query(udp::v4(), host, service);
endpoint_ = *resolver.resolve(query);

}
~udp_client() {
socket_.close();
}

bool sent() {
return sent_;
}

void send(const int r) {
replied_ = false;
sent_ = false;

memcpy(&send_buf_[0],&r,sizeof(int));
std::cout << "prepare sending" << std::endl;

socket_.async_send_to(boost::asio::buffer(send_buf_), endpoint_,
boost::bind(&udp_client::handle_send, this,
boost::asio::placeholders::error,
boost::asio::placeholders::bytes_transferred));
io_service_.run_one();

std::cout << "after run_one" << std::endl;

}

bool replied() {
return replied_;
}

int reply() {
return *reinterpret_cast<int*>(&recv_buf_[0]);
}

private:
void handle_send(const boost::system::error_code& error,
std::size_t size)
{
if (error) {
//missing error propagation to main thread
std::cerr << "ERROR: Client error while sending (error code = " << error << "): " << std::endl;
std::cerr << "ERROR: Recovering..." << std::endl;

} else {
sent_ = true;
std::cout << "sent" << std::endl;
socket_.async_receive_from(boost::asio::buffer(recv_buf_), endpoint_,
boost::bind(&udp_client::handle_receive, this,
boost::asio::placeholders::error,
boost::asio::placeholders::bytes_transferred));
io_service_.run_one();


}
}

void handle_receive(const boost::system::error_code& error,
std::size_t size) {
if (error) {
//missing error propagation to main thread
std::cerr << "ERROR: Client error while receiving (error code = " << error << ")" << std::endl;
std::cerr << "ERROR: Recovering..." << std::endl;

} else {
std::cout << "received" << std::endl;

replied_ = true;
}
}


private:
boost::asio::io_service io_service_;
udp::socket socket_;
udp::endpoint endpoint_;
volatile bool replied_;
volatile bool sent_;
volatile int reply_;
boost::array<char, sizeof(int)> send_buf_;
boost::array<char, sizeof(int)> recv_buf_;

};

int main(int argc, char* argv[]) {

if (argc != 3) {
std::cerr << "Usage: udp_echo_client <host> <port>" << std::endl;
return 1;
}

try {
udp_client c(argv[1],argv[2]);

for(size_t i=0; i != N_MESSAGES; ++i) {
int r = rand();
c.send(r);

//here we could put a tiemeout
while (!c.sent()) {
boost::this_thread::sleep(boost::posix_time::milliseconds(10));
}

//here we could put a tiemeout
while (!c.replied()) {
boost::this_thread::sleep(boost::posix_time::milliseconds(10));
}
int resp = c.reply();

std::cout << "sent= " << r << ", received= " << resp << std::endl;
assert(r == resp);
}

} catch (std::exception& e) {
std::cerr << "ERROR: " << e.what() << std::endl;
}

return 0;
}

我得到的日志是:

$ ./bin/udp_echo_client localhost 11111
prepare sending
sent
received
after run_one
sent= 16807, received= 16807
prepare sending
after run_one

我想这是我对如何使用 boost asio 缺乏了解。所以,如果有人能解释为什么程序会这样,我将不胜感激:)

最佳答案

按照建议推广我的评论:

通常,您需要不断轮询 io_service(或者更恰本地说,只需调用 io_service::run。在这种特殊情况下,您需要调用 io_service::reset()io_service::run_one() 完成后。

关于c++ - UDP Boost ASIO 异步客户端挂起,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/12642643/

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