revlog: add a C implementation of `headrevsdiff`
Python implementation of `headrevsdiff` can be very slow in the worst
case compared with the `heads` computation it replaces, since the
latter is done in C.
Even the average case of this Python implementation is still
noticeable in the profiles.
This patch makes the computation much much faster by doing it in C.
# 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)
"""
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