[英]boost::asio::deadline_timer doesn't call handler
我有一個tcp客戶端,該客戶端會輪詢服務器以獲取截止日期的答案,這樣,如果無法訪問該服務器,則不會阻止該客戶端。 我遇到的問題是async_wait
似乎從未調用過它的處理程序,從而在客戶端無法連接時有效地阻止了客戶端。 每次對tcpPoll
調用tcpPoll
將有其自己的線程(這就是為什么我創建一個新的io_service
),但是即使沒有多線程,它似乎也不起作用。 此外, NetworkEntity
對象可以調用tcpPoll
不止一次其生命周期內。
我的問題是:是什么阻止了deadline_timer
調用其處理程序? (以及解決方法)
這是一些相關的代碼,只要沒有失敗(連接,寫入,讀取)就可以正常工作(抱歉,如果有點長的話):
void NetworkEntity::stop()
{
stopped_ = true;
//close socket
//cancel timeout
}
void NetworkEntity::check_timeout(const boost::system::error_code& error)
{
if (stopped_)
return;
if (timeout_.expires_at() <= boost::asio::deadline_timer::traits_type::now())
{
stop();
timeout_.expires_at(boost::posix_time::pos_infin);
std::cout << address_ << " timed out\n";
}
timeout_.async_wait(boost::bind(&NetworkEntity::check_timeout, this, boost::asio::placeholders::error));
}
std::vector<std::string> NetworkEntity::tcpPoll(const char* message, const char endOfMessage)
{
boost::asio::io_service io_service;
stopped_ = false;
timeout_.expires_from_now(boost::posix_time::seconds(TIMEOUT_));
timeout_.async_wait(boost::bind(&NetworkEntity::check_timeout, this, boost::asio::placeholders::error));
tcp::resolver resolver(io_service);
start_connect(&io_service, resolver.resolve(tcp::resolver::query(address_, port_)), message, endOfMessage);
io_service.run();
//retrieve answer from class
//return answer
}
void NetworkEntity::start_connect(boost::asio::io_service* io_service, tcp::resolver::iterator endpoint_iterator, const std::string message, const char endOfMessage)
{
socket_.reset(new tcp::socket(*io_service));
socket_->async_connect(endpoint_iterator->endpoint(),
boost::bind(&NetworkEntity::handle_connect, this, io_service, boost::asio::placeholders::error, endpoint_iterator, message, endOfMessage));
}
void NetworkEntity::handle_connect(boost::asio::io_service* io_service, const boost::system::error_code& err, tcp::resolver::iterator endpoint_iterator, const std::string message, const char endOfMessage)
{
if(stopped_)
return;
if (err)
{
std::cout << "Connect error: " << err.message() << "\n";
stop();
}
else
{
start_write(message, endOfMessage);
}
}
void NetworkEntity::start_write(const std::string message, const char endOfMessage)
{
std::ostream request_stream(&request_);
request_stream << message;
boost::asio::async_write(*socket_, request_,
boost::bind(&NetworkEntity::handle_write, this, boost::asio::placeholders::error, endOfMessage));
}
void NetworkEntity::handle_write(const boost::system::error_code& error, const char endOfMessage)
{
if (stopped_)
return;
if (!error)
{
//sleep for 500ms to let time for the reciever to process info (had a bug on this one)
start_read(endOfMessage);
}
else
{
std::cout << "write error : " << error.message() << "\n";
stop();
}
}
void NetworkEntity::start_read(const char endOfMessage)
{
boost::asio::async_read_until(*socket_, answer_, endOfMessage,
boost::bind(&NetworkEntity::handle_read, this, boost::asio::placeholders::error));
}
void NetworkEntity::handle_read(const boost::system::error_code& error)
{
if (stopped_)
return;
if (error)
{
std::cout << "read error : " << error.message() << "\n";
stop();
}
else
{
stop();
}
}
我認為您一定對io_service的多個實例感到困惑。
我認為這是因為在您的代碼中您從未展示過如何初始化timeout_
。 而且,用於連接的io_service
實例僅在tcpPoll
函數中實例化...這使我相信您不小心在另一個甚至不運行的io_service上注冊了最后期限計時器?
請注意,這是一個實際有效的版本:
stopped_
布爾值,因為它是不必要的,並且很容易混淆 check_timeout
新實現並stop
如何檢測各種程序流 #include <iostream>
#include <boost/asio.hpp>
#include <boost/bind.hpp>
using tcp = boost::asio::ip::tcp;
struct NetworkEntity {
boost::asio::io_service io_service;
boost::asio::deadline_timer timeout_{io_service};
std::string address_ = "localhost";
std::string port_ = "6767";
int TIMEOUT_ = 3;
boost::shared_ptr<tcp::socket> socket_;
boost::asio::streambuf request_, answer_;
void stop()
{
if (socket_)
{
socket_->cancel();
socket_->close();
}
timeout_.cancel();
io_service.stop();
}
void check_timeout(const boost::system::error_code& error)
{
if (error != boost::asio::error::operation_aborted)
{
stop();
std::cout << address_ << " timed out\n";
}
timeout_.async_wait(boost::bind(&NetworkEntity::check_timeout, this, boost::asio::placeholders::error));
}
std::vector<std::string> tcpPoll(const char* message, const char endOfMessage)
{
timeout_.expires_from_now(boost::posix_time::seconds(TIMEOUT_));
timeout_.async_wait(boost::bind(&NetworkEntity::check_timeout, this, boost::asio::placeholders::error));
tcp::resolver resolver(io_service);
start_connect(&io_service, resolver.resolve(tcp::resolver::query(address_, port_)), message, endOfMessage);
io_service.run();
//retrieve answer from class
//return answer
std::ostringstream oss;
oss << &answer_;
return { oss.str() };
}
void start_connect(boost::asio::io_service* io_service, tcp::resolver::iterator endpoint_iterator, const std::string message, const char endOfMessage)
{
socket_.reset(new tcp::socket(*io_service));
socket_->async_connect(endpoint_iterator->endpoint(),
boost::bind(&NetworkEntity::handle_connect, this, io_service, boost::asio::placeholders::error, endpoint_iterator, message, endOfMessage));
}
void handle_connect(boost::asio::io_service* io_service,
const boost::system::error_code& err,
tcp::resolver::iterator endpoint_iterator,
const std::string message,
const char endOfMessage)
{
if (err)
{
std::cout << "Connect error: " << err.message() << "\n";
stop();
}
else
{
start_write(message, endOfMessage);
}
}
void start_write(const std::string message, const char endOfMessage)
{
std::ostream request_stream(&request_);
request_stream << message;
boost::asio::async_write(*socket_, request_,
boost::bind(&NetworkEntity::handle_write, this, boost::asio::placeholders::error, endOfMessage));
}
void handle_write(const boost::system::error_code& error, const char endOfMessage)
{
if (!error)
{
//sleep for 500ms to let time for the reciever to process info (had a bug on this one)
start_read(endOfMessage);
}
else
{
std::cout << "write error : " << error.message() << "\n";
stop();
}
}
void start_read(const char endOfMessage)
{
boost::asio::async_read_until(*socket_, answer_, endOfMessage,
boost::bind(&NetworkEntity::handle_read, this, boost::asio::placeholders::error));
}
void handle_read(const boost::system::error_code& error)
{
if (error)
{
std::cout << "read error : " << error.message() << "\n";
}
stop();
}
};
int main()
{
NetworkEntity ne;
for (auto& s : ne.tcpPoll("this is my request", '\n'))
{
std::cout << "Line: '" << s << "'\n";
}
}
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