contrib/showstack.py

dispatch: add fail-* family of hooks

The post-* family of hooks will not run in case a command fails (i.e.
raises an exception). This makes it inconvenient to hook into events
such as doing something in case of a failed push.

We catch all exceptions to run the failure hook. I am not sure if this
is too aggressive, but tests apparently pass.

# showstack.py - extension to dump a Python stack trace on signal
#
# binds to both SIGQUIT (Ctrl-\) and SIGINFO (Ctrl-T on BSDs)

from __future__ import absolute_import
import signal
import sys
import traceback

def sigshow(*args):
    sys.stderr.write("\n")
    traceback.print_stack(args[1], limit=10, file=sys.stderr)
    sys.stderr.write("----\n")

def extsetup(ui):
    signal.signal(signal.SIGQUIT, sigshow)
    try:
        signal.signal(signal.SIGINFO, sigshow)
    except AttributeError:
        pass