view contrib/showstack.py @ 46780:6266d19556ad

node: introduce nodeconstants class

In preparing for moving from SHA1 hashes to a modern hash function,
place nullid and other constant magic vules in a class. Provide the
active set of constants in the repository and push it down. Provide
nullid directly in strategic places like the repository as it is
accessed very often. This changeset introduces the API change, but not
the mechanical replacement of the node.py attributes itself.

Differential Revision: https://phab.mercurial-scm.org/D9750

# 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