branchcache: use an explicit class for the v2 version
This prepare the introduction of an experimental v3 format version.
In the process, we move the description of the format in that new class.
# 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