contrib/showstack.py

localrepo: do not cache auditor/nofsauditor which would make reference cycle

Before, self.auditor and self.nofsauditor held self through self._checknested,
and the following code couldn't free a repo by ref-counting.

  def main():
      repo = localrepo.localrepository(uimod.ui(), '../testrepos/hello')
  main()

With this change, the cache of the nofsauditor is limited to a single match
session. I think that's okay as the nofsauditor doesn't do any filesystem
access. Alternatively, maybe we can remove the callback from nofsauditor
since it isn't used unless realfs=True, but I have no idea whether it is
a bug or not.

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