connect_async does not connect when done after loop_start

[igough]

Mosquitto: 1.4.15.0ubuntu
Ubuntu: 16.04

Occasionally, when connect_async is issued shortly after loop_start, an immediate connection does not occur. When connect_async is issued prior to loop_start, a connection always immediately occur. In the code below, if you run it 3 or 4 times, it should fail at least once to connect within 1 second. This appears to be timing sensitive since commenting out the cout << getTime() << " Loop started" << endl; causes it to work.

#include <iostream>
#include <string>
#include <cerrno>
#include <cstring>
#include <chrono>

#include <mosquitto.h>

#if defined(WIN32)
# include <windows.h>
# define sleep(x) Sleep((x)*1000)
#else
# include <unistd.h>
#endif

using namespace std;

static std::chrono::time_point<std::chrono::system_clock>  start;
static bool connected = false;

static double getTime(){
    auto end = std::chrono::system_clock::now();
    std::chrono::duration<double> elapsed_seconds = end-start;
    return elapsed_seconds.count();
  }

void on_connect(struct mosquitto *mosq, void *obj, int rc ){
  cout << getTime() << " ++++++++++ Connected(" << rc << ")" << endl;
  connected = true;
}

void on_disconnect(struct mosquitto *mosq, void *obj, int rc ){
  cout << getTime() << " ---------- Disconnected(" << rc << ")" << endl;
  connected = false;
}

int main (int , char* [])
{
  start = std::chrono::system_clock::now();

  int ret = mosquitto_lib_init ();

  struct mosquitto* c = mosquitto_new ("con-test", true, 0);

  mosquitto_connect_callback_set(c, on_connect);
  mosquitto_disconnect_callback_set(c, on_disconnect);

#define FAILS
#ifndef FAILS
  ret = mosquitto_connect_async (c, "test.mosquitto.org", 1883, 4);
  cout << getTime() << " Connecting" << endl;
#endif

  ret = mosquitto_loop_start (c);
  if ( ret != 0 ){
    cout << getTime() << " Loop start error = " << ret << endl;
  } 
  cout << getTime() << " Loop started" << endl;

#ifdef FAILS
  ret = mosquitto_connect_async (c, "test.mosquitto.org", 1883, 4);
  cout << getTime() << " Connecting" << endl;
#endif

  for ( int i=0; i<200; i++ ){
    if ( connected ){
      cout << getTime() << " Publishing " << i << endl;
      mosquitto_publish( c,nullptr, "foo/bar", sizeof(int), &i, 0, false );
      break;
    } else {
      cout << getTime() << " Waiting for connect..." << endl;
    }
    sleep( 1 );
  }

  ret = mosquitto_disconnect (c);
  ret = mosquitto_loop_stop (c, false);
  ret = mosquitto_lib_cleanup ();
  return 0;
}

[ralight]

I've pushed a change that should fix this. Thanks for the example code, it is very much appreciated. If you want to give it a try please get the fixes branch and close the issue if you're happy.

[igough]

Tested against the fixes branch. The behaviour is better than before in that it consistently connects within 2 seconds. Most of the time, on_connected is called within 300ms of program start, but occasionally, on_connected is called about 1.3 seconds after program start. Reconnect timeout? This longer delay is not ideal, but acceptable. Closing.