我想創建一個專用線程,專門用於使用boost庫(asio)從UDP套接字接收數據。這個線程應該是由從UDP套接字接收到的一些數據觸發的無限循環。在我的應用程序中,我需要使用異步接收操作。boost asio udp套接字async_receive_from不會調用處理程序
如果我使用同步函數receive_from,一切都按預期工作。
但是,如果我使用async_receive_from處理程序永遠不會被調用。由於我使用信號量來檢測是否收到了一些數據,因此程序會鎖定並且從不觸發循環。
我已驗證(使用網絡分析器)發件人設備在UDP套接字上正確發送數據。
我在下面的代碼中隔離了這個問題。
#include <boost\array.hpp>
#include <boost\asio.hpp>
#include <boost\thread.hpp>
#include <boost\interprocess\sync\interprocess_semaphore.hpp>
#include <iostream>
typedef boost::interprocess::interprocess_semaphore Semaphore;
using namespace boost::asio::ip;
class ReceiveUDP
{
public:
boost::thread* m_pThread;
boost::asio::io_service m_io_service;
udp::endpoint m_local_endpoint;
udp::endpoint m_sender_endpoint;
udp::socket m_socket;
size_t m_read_bytes;
Semaphore m_receive_semaphore;
ReceiveUDP() :
m_socket(m_io_service),
m_local_endpoint(boost::asio::ip::address::from_string("192.168.0.254"), 11),
m_sender_endpoint(boost::asio::ip::address::from_string("192.168.0.11"), 5550),
m_receive_semaphore(0)
{
Start();
}
void Start()
{
m_pThread = new boost::thread(&ReceiveUDP::_ThreadFunction, this);
}
void _HandleReceiveFrom(
const boost::system::error_code& error,
size_t received_bytes)
{
m_receive_semaphore.post();
m_read_bytes = received_bytes;
}
void _ThreadFunction()
{
try
{
boost::array<char, 100> recv_buf;
m_socket.open(udp::v4());
m_socket.bind(m_local_endpoint);
m_io_service.run();
while (1)
{
#if 1 // THIS WORKS
m_read_bytes = m_socket.receive_from(
boost::asio::buffer(recv_buf), m_sender_endpoint);
#else // THIS DOESN'T WORK
m_socket.async_receive_from(
boost::asio::buffer(recv_buf),
m_sender_endpoint,
boost::bind(&ReceiveUDP::_HandleReceiveFrom, this,
boost::asio::placeholders::error,
boost::asio::placeholders::bytes_transferred));
/* The program locks on this wait since _HandleReceiveFrom
is never called. */
m_receive_semaphore.wait();
#endif
std::cout.write(recv_buf.data(), m_read_bytes);
}
m_socket.close();
}
catch (std::exception& e)
{
std::cerr << e.what() << std::endl;
}
}
};
void main()
{
ReceiveUDP receive_thread;
receive_thread.m_pThread->join();
}
在旗語甲TIMED_WAIT是優選,然而用於調試目的我使用了一個阻塞等待如在上面的代碼。
我錯過了什麼嗎?我的錯誤在哪裏?
非常感謝!我根據你的建議修改了代碼,一切正常。 我已經在線程創建之前配置了IO服務。到io_service.run()的調用只是線程創建後: \t無效的start() \t { \t \t m_socket.open(UDP :: V4()); \t \t m_socket.bind(m_local_endpoint); \t \t StartRead(); \t \t m_pThread = new boost :: thread(&ReceiveUDP :: _ ThreadFunction,this); \t \t m_io_service.run(); \t} 其中StartRead()是對async_receive_from的調用。 再次感謝。 – arms
謝謝你,我瘋了。 – Alex