Tests of interrupting completion, and completion_nostat_dirs

[Bart Schaefer <schaefer@brasslantern.com>]

[> workers]

On Jan 29, 11:29am, Greg Klanderman wrote:
} Subject: Re: [Feature suggestion] (user configurable) timeout for generati
}
} >>>>> On January 25, 2014 Bart Schaefer <schaefer@brasslantern.com> wrote:
} 
} > On Jan 24,  9:46am, Greg Klanderman wrote:
} > }
} > } For slow completion due to calling out to a separate process for
} > } completions (_git comes to mind) if that is not currently
} > } interruptible it seems like there might be some hope of adding a
} > } timeout or ensuring C-c will interrupt.
} 
} > This is the thing I had a hard time reproducing.  Even if I force
} > the completion function to be very busy with a loop, I can interrupt
} > it.  (Oddly the value of $? is always 0 in _main_complete after I
} > hit ^C, so I can't detect the signal and issue a message.)

Incidentally, here's something I added to _main_complete to make this
easier to test:

------------
diff --git a/Completion/Base/Core/_main_complete b/Completion/Base/Core/_main_complete
index d6831b8..036f1d3 100644
--- a/Completion/Base/Core/_main_complete
+++ b/Completion/Base/Core/_main_complete
@@ -126,6 +126,11 @@ fi
 
 _completer_num=1
 
+# We assume localtraps to be in effect here ...
+integer SECONDS=0
+trap 'zle -M "Killed by signal in ${funcstack[0]} after ${SECONDS}s";
+      zle -R; return 130' INT QUIT
+
 # Call the pre-functions.
 
 funcs=( "$compprefuncs[@]" )
------------

Any objection to that being pushed to the master git?

} Did you try a busy completion function, or external process?

I tried

    _slow() { sleep 30; return 1 }

and the infinite loop

    _slow() {
        while :; do read -E -k 1 -u 0 </dev/zero >/dev/null; done
        return 1
    }

and even

    _slow() {
        SECONDS=0
        while (( SECONDS < 30 )); do : ; done
        return 1
    }

and I was able to interrupt all of them.

} In the original post it seemed that the slow call was probably reading
} a large directory on a slow NFS mount.

Yes, but both that and stat of an automount are going to be disk-wait
blocking accesses to NFS.
 
} I'll attach the patch below, if you'd be willing to incorporate
} something like it let me know, I'd certainly prefer to have it part of
} zsh.  I would add documentation of course.

Hmm, to include this I'd probably want completion_nostat_dirs to be an
autoloaded parameter in the zsh/complete module or something like that.
It doesn't have any of those right now (the magic parameters that are
only valid inside completion widgets are a somewhat different beast) but
there's no reason it couldn't.

On the other hand ZLE_RPROMPT_INDENT is declared in the main shell even
though it's used only by zsh/zle ... anybody else want to weigh in?