My callback for async_write_some is not called after a one second sleep. If I am starting an io_service worker thread for every write, why is the callback not being called?
header
boost::system::error_code error_1;
boost::shared_ptr <boost::asio::io_service> io_service_1;
boost::shared_ptr <boost::asio::ip::tcp::socket> socket_1;
connect
void eth_socket::open_eth_socket (void)
{
// 1. reset io services
io_service_1.reset();
io_service_1 = boost::make_shared <boost::asio::io_service> ();
// 2. create endpoint
boost::asio::ip::tcp::endpoint remote_endpoint(
boost::asio::ip::address::from_string("10.0.0.3"),
socket_1_port
);
// 3. reset socket
socket_1.reset(new boost::asio::ip::tcp::socket(*io_service_1));
// 4. connect socket
socket_1->async_connect(remote_endpoint,
boost::bind(
ð_socket::socket_1_connect_callback,
this, boost::asio::placeholders::error
)
);
// 5. start io_service_1 run thread after giving it work
boost::thread t(boost::bind(&boost::asio::io_service::run, *&io_service_1));
return;
}
write
void eth_socket::write_data (std::string data)
{
// 1. check socket status
if (!socket_1->is_open())
{
WARNING << "socket_1 is not open";
throw -3;
}
// 2. start asynchronous write
socket_1->async_write_some(
boost::asio::buffer(data.c_str(), data.size()),
boost::bind(
ð_socket::socket_1_write_data_callback,
this, boost::asio::placeholders::error,
boost::asio::placeholders::bytes_transferred
)
);
// 3. start io_service_1 run thread after giving it work
boost::thread t(boost::bind(&boost::asio::io_service::run, *&io_service_1));
return;
}
callback
void eth_socket::socket_1_write_data_callback (const boost::system::error_code& error, size_t bytes_transferred)
{
// 1. check for errors
if (error)
{
ERROR << "error.message() >> " << error.message().c_str();
return;
}
if (socket_1.get() == NULL || !socket_1->is_open())
{
WARNING << "serial_port_1 is not open";
return;
}
INFO << "data written to 10.0.0.3:1337 succeeded; bytes_transferred = " << bytes_transferred;
return;
}
test
open_eth_socket();
write_data("Hello"); // callback called
write_data("Hello"); // callback called
write_data("Hello"); // callback called
sleep(1);
write_data("Hello"); // callback not called after sleep
boost::thread t(boost::bind(&boost::asio::io_service::run, *&io_service_1));
That's weird for a number of reasons.
io_service::work to prevent run from returning.io_service again after it returned (without error) you should call reset() first, as per documentation (Why must io_service::reset() be called?)std::thread this would even have caused immediate abnormal program termination. It's bad practice to not-join non-detached threads (and I'd add it's iffy to use detached threads without explicit synchronization on thread termination). See Why is destructor of boost::thread detaching joinable thread instead of calling terminate() as standard suggests?I'd add to these top-level concerns
socket_1 (just call it socket_ and instantiate another object with a descriptive name to contain the other socket_). I'm not sure, but the question does raise suspicion these might even be global variables. (I hope that's not the case)throw-ing raw integers, really?io_service while never checking that worker threads had completed.More Undefined Behaviour here:
_sock.async_write_some(
ba::buffer(data.c_str(), data.size()),
You pass a reference to the parameter data which goes out of scope. When the async operation completes, it will be a dangling reference
There's some obvious copy/paste trouble going on here:
if (socket_1.get() == NULL || !socket_1->is_open())
{
WARNING << "serial_port_1 is not open";
return;
}
I'd actually say this stems from precisely the same source that lead to the variable names being serial_port_1 and socket_1
Simplify. There wasn't self-contained code, so nothing complete here, but at least see the many points of simplification:
#include <boost/asio.hpp>
#include <boost/thread.hpp>
#include <iostream>
namespace ba = boost::asio;
using ba::ip::tcp;
using boost::system::error_code;
#define ERROR std::cerr
#define WARNING std::cerr
#define INFO std::cerr
struct eth_socket {
~eth_socket() {
_work.reset();
if (_worker.joinable())
_worker.join(); // wait
}
void open(std::string address);
void write_data(std::string data);
private:
void connected(error_code error) {
if (error)
ERROR << "Connect failed: " << error << "\n";
else
INFO << "Connected to " << _sock.remote_endpoint() << "\n";
}
void written(error_code error, size_t bytes_transferred);
private:
ba::io_service _svc;
boost::optional<ba::io_service::work> _work{ _svc };
boost::thread _worker{ [this] { _svc.run(); } };
std::string _data;
unsigned short _port = 6767;
tcp::socket _sock{ _svc };
};
void eth_socket::open(std::string address) {
tcp::endpoint remote_endpoint(ba::ip::address::from_string(address), _port);
_sock.async_connect(remote_endpoint, boost::bind(ð_socket::connected, this, _1));
}
void eth_socket::write_data(std::string data) {
_data = data;
_sock.async_write_some(ba::buffer(_data), boost::bind(ð_socket::written, this, _1, _2));
}
void eth_socket::written(error_code error, size_t bytes_transferred) {
INFO << "data written to " << _sock.remote_endpoint() << " " << error.message() << ";"
<< "bytes_transferred = " << bytes_transferred << "\n";
}
int main() {
{
eth_socket s;
s.open("127.0.0.1");
s.write_data("Hello"); // callback called
s.write_data("Hello"); // callback called
s.write_data("Hello"); // callback called
boost::this_thread::sleep_for(boost::chrono::seconds(1));
s.write_data("Hello"); // callback not called after sleep
} // orderly worker thread join here
}