Howto implement timeout

Question

Ok I have the following problem...
I have multiple VI's. Most of these VI's contain a loop which can theoratically loop a infinit amount of time. Some VI's which can run infinitly call VI's which can run infinitly. Now my problem is how do I timeout them. 
I got a few solutions but none that I like. 
Currently I have the following (not wanted implementation). Each VI has a timeout input. Then inside the VI I check if the VI has timed out. Now this implementation is flawed because of the following. I have A.vi and B.vi. A.vi calls B.vi. A.vi and B.vi have a input timeout. I wire the timeout of A.vi to B.vi. Now the flaw in my current design is that the timeout is sort of relative. Before B.vi is called in A.vi already some time has passed. Thus when B.vi is called in A.vi with that timeout it is possible that while B.vi is running A.vi would have timeout... but this does not happen because B.vi is still running with the same timeout of A, hence gets extended, because the timeout is added with the time when the VI is called and then compared when running. I attachted a sample VI of my current implementation. 
Now I want to be able to have a more abstract method. Something like a VI which holds the timeout. I was thinking of a functional global... however this would conflict when two VI's are running with different timeouts which both call that VI when they run in parallel. 
Hopefully someone has a clever idea/solution.
Attachments:
A.vi ‏10 KB
B.vi ‏9 KB

Answer 1

If A.vi calls B.vi, and you expect B.vi to be done in 100 ms it's naturally impossible for A.vi to be done in 100 ms as well if B.vi times out. You can use the timed elapsed in B output and add it to the time elapsed in A to compare it with the timeout instead. However if B does time out A will still take a bit longer to time out.
Hmmm wel that would not be possible of course because what when B will execute infinitly...
If your current approach is as simple as the demo VIs you attached, you may very rarely run into a problem when the Tick Counter rolls over, giving you a much longer timeout than you expect.  (Of course, loops with no wait are also a problem).
Sounds like what you want is to change your timeout inputs to "Timeout At" inputs, so that it times out at a given time.  Instead of comparing with the Tick Count, compare with Get Date/Time in Seconds (this also solves the rollover problem).  Then you can pass the same Timeout At value from A directly into B.  Alternatively, add the Timeout At input instead of replacing the Timeout, and set the initial value to NaN.  Check if the input is NaN - if so, get the current time in seconds, add the timeout value, and use that as the new Timeout At; otherwise, just use the Timeout At value that was passed in.
Yes I actually came up with this solution also "Timeout At" idea. But I don't really like it, I was hoping for a more abstract/generic method. Where I could just use the tickcount. 
The real issue lies in fact with the problem that I can't determine which VI's are going to be called and because they can be executed in parallel. If I could do this I could just create a notifier for that set of VI's which need a timeout check.