add --daemon option to serve command. for issue 45.
code looks odd because it is portable to windows. windows does not have
os.fork, so have to spawn and use pipe to tell parent ready instead.
# lock.py - simple locking scheme for mercurial
#
# Copyright 2005 Matt Mackall <mpm@selenic.com>
#
# This software may be used and distributed according to the terms
# of the GNU General Public License, incorporated herein by reference.
import os, time
import util
class LockHeld(Exception):
pass
class lock(object):
def __init__(self, file, wait=1, releasefn=None):
self.f = file
self.held = 0
self.wait = wait
self.releasefn = releasefn
self.lock()
def __del__(self):
self.release()
def lock(self):
while 1:
try:
self.trylock()
return 1
except LockHeld, inst:
if self.wait:
time.sleep(1)
continue
raise inst
def trylock(self):
pid = os.getpid()
try:
util.makelock(str(pid), self.f)
self.held = 1
except (OSError, IOError):
raise LockHeld(util.readlock(self.f))
def release(self):
if self.held:
self.held = 0
if self.releasefn:
self.releasefn()
try:
os.unlink(self.f)
except: pass