contrib/showstack.py

statichttprepo: implement wlock() (issue5613)

statichttprepo inherits from localrepository. In doing so, it
obtains default implementations of various methods, like wlock().

Before this change, tags cache writing would call repo.wlock().
This failed on statichttprepo due to localrepository's wlock()
looking for an instance attribute that doesn't exist on statichttprepo
(statichttprepo doesn't call localrepository.__init__).

We /could/ define missing attributes until the base wlock() works.
However, a statichttprepo is remote and read-only and can't be
locked. The class already has a lock() that short circuits. So
it makes sense to implement a short-circuited wlock() as well. That
is what this patch does.

LockError is expected to be raised when locking fails. The constructor
takes a number of arguments that are local repository centric. Rather
than rework LockError to not require them (which would not be
appropriate for stable), this commit populates dummy values. I don't
believe they'll ever be seen by the user, as lock failures on
static http repos should be limited to well-defined (and tested)
scenarios. We can and should revisit the LockError type to improve
this.

# 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