contrib/showstack.py

transaction: issue "new obsmarkers" message at the end of the transaction

Instead of making bundle2 code responsible for this, it seems better to have it
handled and the transaction level. First, it means the message will be more
consistently printed. Second it means we won't spam the message over and over if
the data arrive in multiple piece. Third, we are planning to move other similar
message at the same level (for the same reason) so having them all at the same
location will help us to control the order they are displayed.

# 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