Opened 11 years ago

Last modified 8 years ago

#9640 closed enhancement

Change PARI error catching mechanism — at Version 10

Reported by: jdemeyer Owned by: was
Priority: major Milestone: sage-5.13
Component: interfaces Keywords: pari error interrupt
Cc: leif, jdemeyer Merged in:
Authors: Peter Bruin Reviewers:
Report Upstream: N/A Work issues:
Branch: Commit:
Dependencies: Stopgaps:

Status badges

Description (last modified by pbruin)

Currently, the exceptions thrown by PARI are rather cryptic, like

Traceback (most recent call last):
...
PariError:  (15)

This ticket does the following:

  • Use cb_pari_handle_exception() instead of err_catch() to catch PARI exceptions.
  • Using a mechanism similar to #9636, catch the full text of the exception and pass it to PariError. (It is not printed automatically, but can be accessed via PariError.errtext().)

Apply: 9640-pari_error_callbacks.patch

Change History (12)

comment:1 Changed 11 years ago by jdemeyer

  • Description modified (diff)

comment:2 Changed 11 years ago by leif

  • Authors set to Jeroen Demeyer
  • Cc leif added

Changed 11 years ago by jdemeyer

Old patch for reference

comment:3 Changed 11 years ago by jdemeyer

  • Description modified (diff)
  • Keywords pari error interrupt added

comment:4 Changed 8 years ago by jdemeyer

  • Milestone changed from sage-5.11 to sage-5.12

comment:5 Changed 8 years ago by pbruin

  • Cc pbruin added

comment:6 Changed 8 years ago by pbruin

I am working on a patch that does the following things suggested by the ticket description:

  • Rewrite pari_catch_sig_on() and pari_catch_sig_off() to use the callbacks cb_pari_handle_exception and cb_pari_err_recover (defined by the PARI library) in combination with sig_on()/sig_off(), as opposed to the additional setjmp() of the current implementation.
  • Catch output sent to pariErr and store it in a string attribute pari_instance.error_string for later use by PariError.

It seems to work quite well; the only doctest failures I've seen so far are a few tests expecting a PARI warning message. With the patch, these are not printed because they also go to pariErr.

To be done:

  • Make PariError aware of the stored string to give a more informative error message. This should probably simply be extracted from the lines starting with *** in pari_instance.error_string.
  • Minor change in PARI: send any extra newline at the start of the error message to pariErr instead of pariOut (this happens if the last printed character was not a newline).
  • Distinguish between errors and warnings; the latter should probably be printed to stderr as before. This should be done either by filtering the text sent to pariErr or by having pari_catch_sig_off() check if pari_instance.error_string is non-empty even if no error occurred.

This may make #14894 redundant, although that ticket could be used for general things to be done for the upgrade to PARI 2.6.

Changed 8 years ago by pbruin

based on 5.12.beta4 + #15124

comment:7 Changed 8 years ago by pbruin

  • Status changed from new to needs_review
  • Work issues set to see comment 6

The attached patch passes doctests on x86_64 GNU/Linux, except for two tests expecting a PARI warning (see above).

comment:8 Changed 8 years ago by pbruin

  • Status changed from needs_review to needs_work

comment:9 Changed 8 years ago by pbruin

  • Authors changed from Jeroen Demeyer to Peter Bruin
  • Cc jdemeyer added; pbruin removed

It would be better practice to move _pari_init_err(), _pari_handle_exception() and _pari_err_recover() from pari_err.h to a C file or to translate them to Cython. At the moment I don't think it is worth the trouble.

comment:10 Changed 8 years ago by pbruin

  • Description modified (diff)
  • Status changed from needs_work to needs_review
  • Work issues see comment 6 deleted

The latest patch does everything that I think it should do. I hope it is reasonably self-explanatory. A few remarks:

  • The error text is now passed to PariError and can be accessed using PariError.errtext(); is is not printed automatically. Using this text to improve messages like PariError: (15) will probably have to wait until another ticket. (Edit: user errors are an exception, since they are converted into RuntimeError; here we append the error text to the currently used "PARI user exception".)
  • There is no problem with PARI sending escape sequences for colours in error messages; this is disabled by default.
  • The printing of a possible extra newline before the error message is easily avoided using pari_set_last_newline(1).
  • The callback functions are now Cython functions in the new file pari_error.pyx. It is important that this does not include pari_err.pxi; because of the way Cython imports functions, pari_err.pxi and pari_err.h use function pointers with the same names as the functions defined in pari_error.pyx.
Last edited 8 years ago by pbruin (previous) (diff)
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