contrib/showstack.py

share: rework config options to be much clearer and easier

Recently I implemented various boolean configs which control how to behave when
there is a share-safe mismatch between source and share repository. Mismatch
means that source supports share-safe where as share does not or vice versa.

However, while discussion and documentation we realized that it's too
complicated and there are some combinations of values which makes no sense.

We decided to introduce a config option with 4 possible values which
makes controlling and understanding things easier.

The config option `share.safe-mismatch.source-{not-}safe` can have
following 4 values:

* abort (default): error out if there is mismatch
* allow: allow to work with respecting share source configuration
* {up|down}grade-abort: try to {up|down}grade, if it fails, abort
* {up|down}grade-allow: try to {up|down}grade, if it fails, continue in allow
mode


I am not sure if I can explain 3 config options which I deleted right now in
just 5 lines which is a sign of how complex they became.

No test changes demonstrate that functionality is same, only names have changed.

Differential Revision: https://phab.mercurial-scm.org/D9785

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

from __future__ import absolute_import, print_function
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 sigexit(*args):
    sigshow(*args)
    print('alarm!')
    sys.exit(1)


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