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Feature #1755

CheckForInterrupt: give more info?

Added by John Abbott 10 months ago. Updated 4 months ago.

Status:
Closed
Priority:
High
Assignee:
John Abbott
Category:
Improving
Target version:
CoCoALib-0.99850
Start date:
13 Jul 2023
Due date:
% Done:

100%

Estimated time:
1.90 h
Spent time:
1.80 h

Description

This may be not so important...
Today I wanted to interrupt a long loop and know roughly how far the computation had proceeded.
Currently CheckForInterrupt does not do this...

It is currently possible by calling GetAndResetSignalReceived (defined in SignalWatcher).

We should document how a user can more info when a signal is handled.

History

#1 Updated by John Abbott 10 months ago

Here is how I managed it in my ad hoc program:

    for (long n=10000001; n < 20000000; n += 2)
    {
      if (!IsSqFree(n)) continue;
//      CheckForInterrupt("main loop"); // does not say how far we reached
      if (GetAndResetSignalReceived()) { cout << endl << "INTR at n=" << n << endl; break; }
      .....
    }

#2 Updated by John Abbott 10 months ago

While it is not really much shorter, I was thinking of trying to implement an extension of CheckForInterrupt which takes a 2nd arg which will be printed if an interrupt occurs. Hmmm, but if I do not use a macro then the 2nd arg will always be evaluated :-/

    for (long n=10000001; n < 20000000; n += 2)
    {
      if (!IsSqFree(n)) continue;
      CheckForInterrupt("main loop", n);
      .....
    }

It would be best not to use a MachineInt for the 2nd arg, as otherwise the ctor will always be called.
Maybe I could make it a template function? (but that tends to expose more impl details than I'd like...)

KISS: for first impl make 2nd arg of type long??

#3 Updated by John Abbott 10 months ago

  • Status changed from New to Feedback
  • Assignee set to John Abbott
  • % Done changed from 0 to 90

After discussing with Anna (by phone), we think that extending CheckForInterrupt as suggested in comment 2 above is not really such a good idea.

Here are some reasons:
  • the proposed extension is of limited flexibility; moreover the extra information is printed only when verbosity is at least 11 (which was not really what I had expected)
  • the proposed solution/workaround in comment 1 is not so bad, but we must document it properly (with an example!) It also offers the user complete flexibility (while avoiding potentially evaluating expressions which are then simply discarded e.g. if the extra arg to CheckForInterrupt is non-trivial)
  • how often does one really want the extra information? (JAA suspects only rarely)
  • one can also use ProgressReporter (which is probably more informative); of course, it won't report exactly where the loop was when interrupted...

We are inclined to reject this idea; but for the moment I have put the issue into feedback in case any more thoughts come to mind.

#4 Updated by John Abbott 9 months ago

  • Priority changed from Low to High

Create an example of using GetAndResetSignalReceived

#5 Updated by John Abbott 4 months ago

  • Status changed from Feedback to Closed
  • % Done changed from 90 to 100
  • Estimated time set to 1.90 h

I have made a new example ex-interupt3.C which illustrates the idea from comment 1.

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