contrib/showstack.py

hg: allow extra arguments to be passed to repo creation (API)

Currently, repository creation is influenced by consulting the
ui instance and turning config options into requirements. This
means that in order to influence repository creation, you need
to define and set a config option and that the option must translate
to a requirement stored in the .hg/requires file.

This commit introduces a new mechanism to influence repository
creation. hg.repository() and hg.peer() have been taught to
receive a new optional argument defining extra options to apply
to repository creation. This value is passed along to the various
instance() functions and can be used to influence repository
creation. This will allow us to pass rich data directly to repository
creation without having to go through the config layer. It also allows
us to be more explicit about the features requested during repository
creation and provides a natural point to detect unhandled options
influencing repository creation. The new code detects when unknown
creation options are present and aborts in that case.

.. api:: options can now be passed to influence repository creation

   The various instance() functions to spawn new peers or repository
   instances now receive a ``createopts`` argument that can be a
   dict defining additional options to influence repository creation.

   localrepo.newreporequirements() also receives this argument.

Differential Revision: https://phab.mercurial-scm.org/D4535

# 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