`message_queue::timed_receive` block process a long duration than expect when `system time` jumb back

[jerryhuangcc]

In my project, I use message_queue::timed_receive to handle inter process messaging.

But in issue scenario, my system clock falled back to 2mins, then timed_receive waited for more than 1s already set in code. This behaviour is not expected.

while (true)
{
     // var defination
     if (message_queue.timed_receive(&message, sizeof(message), received_size, priority, std::chrono::seconds(1))) 
    {
           handle(message); 
    }

    // other logics

}

My question is for message_queue::timed_receive, does it support steady_clock which is not affected by system time update?

[igaztanaga]

timed_receive expects an absolute time and you are passing a duration. In any case, even if an absolute time is passed that depends on which time the underlying operating system uses. In POSIX systems, the default clock is the real-time clock (CLOCK_REALTIME):

https://pubs.opengroup.org/onlinepubs/009695399/functions/pthread_cond_timedwait.html

In some recent systems (Linux) it might be possible to configure POSIX condition variables to use CLOCK_MONOTONIC instead but in any case, we can't have a general guarantee about steady clock (monotonic) support.