C ++ Threading Question

Question

I have a Foo object that has a global variable, Time currentTime

Foo has two methods that are called from different threads.

update()
{
    currentTime = currentTime + timeDelay;
}

restart(Time newTime)
{
    currentTime = newTime;
}

I see a reboot behavior, the time changes correctly at other times when currentTime does not look like reset (or it does reset, and then updates it somehow).

A method update is called about every second or so, while a restart only occurs when the user triggers a restart event (presses the button). I think this is a timetable issue, any suggestions or comments on what is happening are welcome.

Answer 1

, , . currentTime . mutex Boost.Threads:

class Foo
{
  boost::mutex _access;
  update()
  {
    boost::mutex::scoped_lock lock(_access);
    currentTime = currentTime + timeDelay;
  }

  restart(Time newTime)
  {
    boost::mutex::scoped_lock lock(_access);
    currentTime = newTime;
  }
};

Answer 2

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Answer 3

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, , : http://en.wikipedia.org/wiki/Mutual_exclusion

Answer 4

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update()
{
    // Lock mutex
    currentTime = currentTime + timeDelay;
    // unlock mutex
}
// Same idea for restart()

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Answer 5

. InterlockedExchange InterlockedAdd.

Answer 6

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Answer 7

currentTime , , , . (PTHREAD_MUTEX_INITIALIZER BOOST.call_once)

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