How can I exit [NSRunLoop runUntilDate]?

Question

I am writing an application which has to communicate with a device connected via USB. The app sends and receives data in turns from the device on a fixed timing. All Rx/Tx happens in a separate thread because otherwise the UI would be blocked. The basic structure looks basically like this. (autorelease pools and stuff omitted)

-(void)comThread:(id)arg {
  while(state == kIsConnected) {
    // let timers run
    [runLoop runUntilDate:[NSDate distantFuture]];
    // handle data
    if(rxTxState == kRx) {
      // do some stuff to pass data to upper layers
      rxTxState = kTx;
    }
    if(rxTxState == kTx) {
      // do some stuff to send data
      rxTimeoutTimer = [NSTimer scheduledTimer....];
    }
  } 
}

After sending data, the app waits for either data to be received or the rxTimeoutTimer to fire which leads to retransmission of the packet. The rx-operation works since the underlying layers use async system calls and calls a rx-handler which look basically like this.

-(void)receiveData:(NSData*)data{
  [rxQueue addObject:data];
  [rxTimeoutTimer invalidate];  // cancel timeout
}

Is there an (easy) way to make the [runLoop runUntilDate:] exit from receiveData:? The Apple docs say that removing all timer sources does not guarantee the RunLoop to exit. I read something about calling performSelector:onThread:... but it either did not work or I did not get the point.

Thanks.

score 9 · Answer 1 · answered Jan 11 '10 at 21:04

9

CFRunLoopStop([runLoop getCFRunLoop]);

answered Jan 11 '10 at 21:04

kennytm

510,854
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1,084
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Or, without the 'runLoop' local variable: CFRunLoopStop([[NSRunLoop currentRunLoop] getCFRunLoop]); – rpj Jan 20 '10 at 19:27
3

@rpj: You use `CFRunLoopGetCurrent()` in that case :) – kennytm Jan 20 '10 at 19:30

score 5 · Answer 2 · answered Jan 11 '10 at 21:05

5

The standard pattern is to run the runloop for some timeout period (e.g. 0.5 seconds), and then iterate until the task is accomplished:

while(state == kIsConnected) {
  while(!iterationDone) {
    [runLoop runUntilDate:[NSDate dateWithTimeIntervalSinceNow:0.5]];
    //do other stufff
  }
}

-(void)receiveData:(NSData*)data{
  [rxQueue addObject:data];
  [rxTimeoutTimer invalidate];  // cancel timeout
  iterationDone = YES;
}

answered Jan 11 '10 at 21:05

Barry Wark

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The whole timeout is 0.5 seconds in my case. I would have to run the RunLoop for fractions of this time like 0.05 seconds. I wonder if it really has this resolution. – insanelygreat Jan 12 '10 at 18:11
It really has this resolution. – rpj Jan 20 '10 at 19:26
The `-runMode:beforeDate:` method with a `distantFuture` argument might work too, since it processes one input source then returns, at which point the `while` condition would be checked and (if it's true) the run loop restarted. – nevan king Mar 13 '18 at 12:48

score 0 · Answer 3 · answered Sep 22 '14 at 06:41

CFRunLoopStop([runLoop getCFRunLoop]); and CancelPerformSelector

didnot work for me , See my Code for running [NSRunLoop currentRunLoop]

timerUpdateLocation = [NSTimer scheduledTimerWithTimeInterval:[time intValue] target:self selector:@selector(startTrackingBg) userInfo:nil repeats:YES];
[[NSRunLoop currentRunLoop] addTimer:timerUpdateLocation forMode:NSRunLoopCommonModes];
[[NSRunLoop currentRunLoop] run];

To Stop it I Just invalidate timer.

[timerUpdateLocation invalidate];

score 0 · Answer 4 · answered Dec 14 '15 at 11:02

Do like this can exit. but it will exit after a few seconds.

 -(void)comThread:(id)arg {
      BOOL ret = YES;
      rxTimeoutTimer = [NSTimer scheduledTimer....];
      while(ret) {
        // let timers run
        ret = [runLoop runUntilDate:[NSDate distantFuture]];
      } 
    }
    -(void)receiveData:(NSData*)data{
      [rxQueue addObject:data];
      [rxTimeoutTimer invalidate];  // cancel timeout
      iterationDone = YES;
    }

the kennytm's answer seems right.

How can I exit [NSRunLoop runUntilDate]?

4 Answers4