Boost Threading : Mutex with Conditional Variable ,main thread hanging

[HA-AS]

Hello,

I am trying to implement a state machine as a part of a class called" Source Transaction". Evey-time I receive a request in the main thread, it generates an instance of this class and the state machine starts executing until it reaches a state where it has to wait for a response in the main thread in the "event_handler". To solve this issue, I am implementing a conditional variable using boost libraries as following:

Source Transaction Class
 

boost::mutex mut;
    boost::condition_variable cond;
 
    wait_ho_complete_indication_state:
    {
        mState = SRC_WAIT_HO_COMPLETE_INDICATION;
 
        boost::unique_lock<boost::mutex> lock(mut);
        while (!response_received)
        {
            cond.wait(lock);
        }
 
        response_received = false;
        goto success_state;
    } 

And in the main file I have the following:

Main Class

Event_Handler function:

        // Find the source transaction which corresponds to this Indication
        src_transaction_ptr t;
        tpool->find(msg.source(), mobile_id.to_string(), t);
        {
            boost::lock_guard<boost::mutex> lock(t->mut);
            t->response_received = true;
        }
        t->cond.notify_one();
        // Dome some stuff
 

My problem is, every-time I execute the code, the state machine gets trapped in the "wait_ho_complete_indication_state" and it doesn't leave that state ,and additional to that the event_handler doesn't report that it has received any event. Like the main is being hanged.

So my question is there any problem in the implementation of the conditional variable?

Thanks a lot.

[Elkvis]

why are you using goto? goto is bad. always.

[HA-AS]

why are you using goto? goto is bad. always.

I am using goto, to move between different states of the State Machine. But my problem is why, the main thread gets hanged? Not the goto.

Is there any problem in my conditional variable definition?

[Elkvis]

I don't see anything wrong with your initialization of the condition variable, although your goto could easily be the problem. If the goto jumps into a different function or jumps over initialization of other variables, it can cause undefined and/or unexpected behavior. You really aren't showing enough code to be helpful.

[Codeplug]

>> ... additional to that the event_handler doesn't report that it has received any event.
If the "Event_Handler function" is never run, then the condition is never signaled. I would look into why your event handler isn't being called.

Condition usage looks fine, though I prefer to call notify_xxx while the lock is still acquired - condvars: signal with mutex locked or not? | Loïc OnStage

Mixed use of unique_lock and lock_guard looks inconsistent.

gg

[HA-AS]

@Codeplug. thanks for your reply.
Actually what's happening is the program freezes, the main thread and all the newly created thread. I also have a separate thread for a TCP server, and it doesn't respond at all.
The event handler is never executed in the main thread. And regarding the use of the lock_gaurd and unique_lock I am following the boost documentation exactly as following:

Synchronization - 1.49.0

@Elkvis. All the threads which are created and correspond to the State machine, are really working good. I don't think the problem is from the goto.

I don't know why the whole program is freezing.