[Twisted-Python] failures, errbacks and exception handling
drew.smathers at gmail.com
Tue Apr 8 16:18:30 EDT 2008
On Tue, Apr 8, 2008 at 2:40 PM, Atilla <theatilla at gmail.com> wrote:
> Im a little confused when it comes to handling some errors in twisted.
> More specifically - when it comes to processing failures that are
> raised in adbapi.
> Now - when runInteraction succeeds, all is ok and things are commited,
> that's nice and clean. When it raises an error, I can do two things -
> either wrap my calls inside the callable passes to runInteraction in
> Try:Except, or attach an errback.
> I'm not exactly sure which one to take. I only need to catch specific
> exceptions - Mysql OperationalError (timeouts and such, in case I want
> to retry). Everything else is critical and should log & abort.
> The way I understood it, I should attach an errback where I call
> trap() on the passed Failure. So I'd do like
> error = failure.trap(OperationalError)
> if error:
> As far as I get it, if the error is different (say, syntax one) it'll
> be propagated. However afteri add the trap call() nothing else gets
> past that handleError, no Unhandled Errors are logged, and my error
> object contains nothing. I wonder what am I missing here.
That really depends on what you want to do. If you just want to log
the exception (IndexError, etc) that you're not trapping, consider
creating a last ditch error handler like:
log.err('ERROR: %s' % reason)
... Do the rollback or whatever else ...
And add the above to your errback chain:
\\\\/ // //\/\\\\\\\
\\\/ \\// /\ \/\\\\
\\/ /\/ / /\/ /\ \\\
\/ / /\/ /\ /\\\ \\
/ /\\\ /\\\ \\\\\/\
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