Is it possible to use a timer to kill rogue method in background thread?

I have a piece of code that calls a method (i.e. processRege开发者_如何学JAVAx) which is from a 3rd party library, regexKitLite, that runs a regex match on a bunch of data. I am running this method in a bg thread using performSelectorInBackground:. I have found that in some cases if the data is invalid or corrupted then the processRegex method locks up the thread and gets caught in a recursive loop which could take forever to come back which i obv would like to avoid.

I was thinking of using a timer that basically waits x amount of time and if it hasnt been invalidated before the specified time passes it then kills the bg thread that is running the method.

My problem however is:

I cant launch the timer in the same thread as the regex method because that thread could lock up while trying to process the data and wouldnt call my timer as i tried below.

// setup timer to restrict the amount of time a regex can take before killing it
myTimer = [NSTimer scheduledTimerWithTimeInterval:10.0 target:self selector:@selector(resultProcessingTimedOut:) userInfo:nil repeats:NO];

resultsArray = [NSMutableArray arrayWithArray:[html arrayOfCaptureComponentsMatchedByRegex:]; // <-- could lock up thread!!

[myTimer invalidate];

Secondly, according to the apple docs you have to invalidate the timer in the same thread that started it and i cant launch the timer in its own background thread because im not sure how i would then invalidate it?

Lastly, how would i even kill the thread that is running the regex as you are not supposed to terminate threads.

Any ideas on how to deal with this situation???

thx

In short, no, you cannot kill another thread arbitrarily. There is no way to know what state it'll be in when killed and, thus, the memory leaks and/or corruption are bound to happen.

You can solve this in one of several ways (including combining):

• modify the regexkit to have some kind of "stop" flag that can be set after the timer fires in another thread. Periodically check it and clean up / stop when needed.

• validate or limit the input regular expression and input data to ensure that the slow/long situation doesn't happen

• break up the input data such that you can batch process it.