contrib/showstack.py

revset: don't cache abstractsmartset min/max invocations infinitely

There was a "leak", apparently introduced in ab66c1dee405. When running:

    hg = hglib.open('repo')
    while True:
        hg.log("max(branch('default'))")

all filteredset instances from branch() would be cached indefinitely by the
@util.cachefunc annotation on the max() implementation.

util.cachefunc seems dangerous as method decorator and is barely used elsewhere
in the code base. Instead, just open code caching by having the min/max
methods replace themselves with a plain lambda returning the result.

# 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