hg: obtain lock when creating share from pooled repo (issue5104)
There are race conditions between clients performing a shared clone
to pooled storage:
1) Clients race to create the new shared repo in the pool directory
2) 1 client is seeding the repo in the pool directory and another goes
to share it before it is fully cloned
We prevent these race conditions by obtaining a lock in the pool
directory that is derived from the name of the repo we will be
accessing.
To test this, a simple generic "lockdelay" extension has been added.
The extension inserts an optional, configurable delay before or after
lock acquisition. In the test, we delay 2 seconds after lock acquisition
in the first process and 1 second before lock acquisition in the 2nd
process. This means the first process has 1s to obtain the lock. There
is a race condition here. If we encounter it in the wild, we could
change the dummy extension to wait on the lock file to appear instead
of relying on timing. But that's more complicated. Let's see what
happens first.
# formatter.py - generic output formatting for mercurial
#
# Copyright 2012 Matt Mackall <mpm@selenic.com>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
from __future__ import absolute_import
import cPickle
import os
from .i18n import _
from .node import (
hex,
short,
)
from . import (
encoding,
error,
templater,
)
class baseformatter(object):
def __init__(self, ui, topic, opts):
self._ui = ui
self._topic = topic
self._style = opts.get("style")
self._template = opts.get("template")
self._item = None
# function to convert node to string suitable for this output
self.hexfunc = hex
def __nonzero__(self):
'''return False if we're not doing real templating so we can
skip extra work'''
return True
def _showitem(self):
'''show a formatted item once all data is collected'''
pass
def startitem(self):
'''begin an item in the format list'''
if self._item is not None:
self._showitem()
self._item = {}
def data(self, **data):
'''insert data into item that's not shown in default output'''
self._item.update(data)
def write(self, fields, deftext, *fielddata, **opts):
'''do default text output while assigning data to item'''
fieldkeys = fields.split()
assert len(fieldkeys) == len(fielddata)
self._item.update(zip(fieldkeys, fielddata))
def condwrite(self, cond, fields, deftext, *fielddata, **opts):
'''do conditional write (primarily for plain formatter)'''
fieldkeys = fields.split()
assert len(fieldkeys) == len(fielddata)
self._item.update(zip(fieldkeys, fielddata))
def plain(self, text, **opts):
'''show raw text for non-templated mode'''
pass
def end(self):
'''end output for the formatter'''
if self._item is not None:
self._showitem()
class plainformatter(baseformatter):
'''the default text output scheme'''
def __init__(self, ui, topic, opts):
baseformatter.__init__(self, ui, topic, opts)
if ui.debugflag:
self.hexfunc = hex
else:
self.hexfunc = short
def __nonzero__(self):
return False
def startitem(self):
pass
def data(self, **data):
pass
def write(self, fields, deftext, *fielddata, **opts):
self._ui.write(deftext % fielddata, **opts)
def condwrite(self, cond, fields, deftext, *fielddata, **opts):
'''do conditional write'''
if cond:
self._ui.write(deftext % fielddata, **opts)
def plain(self, text, **opts):
self._ui.write(text, **opts)
def end(self):
pass
class debugformatter(baseformatter):
def __init__(self, ui, topic, opts):
baseformatter.__init__(self, ui, topic, opts)
self._ui.write("%s = [\n" % self._topic)
def _showitem(self):
self._ui.write(" " + repr(self._item) + ",\n")
def end(self):
baseformatter.end(self)
self._ui.write("]\n")
class pickleformatter(baseformatter):
def __init__(self, ui, topic, opts):
baseformatter.__init__(self, ui, topic, opts)
self._data = []
def _showitem(self):
self._data.append(self._item)
def end(self):
baseformatter.end(self)
self._ui.write(cPickle.dumps(self._data))
def _jsonifyobj(v):
if isinstance(v, tuple):
return '[' + ', '.join(_jsonifyobj(e) for e in v) + ']'
elif v is None:
return 'null'
elif v is True:
return 'true'
elif v is False:
return 'false'
elif isinstance(v, (int, float)):
return str(v)
else:
return '"%s"' % encoding.jsonescape(v)
class jsonformatter(baseformatter):
def __init__(self, ui, topic, opts):
baseformatter.__init__(self, ui, topic, opts)
self._ui.write("[")
self._ui._first = True
def _showitem(self):
if self._ui._first:
self._ui._first = False
else:
self._ui.write(",")
self._ui.write("\n {\n")
first = True
for k, v in sorted(self._item.items()):
if first:
first = False
else:
self._ui.write(",\n")
self._ui.write(' "%s": %s' % (k, _jsonifyobj(v)))
self._ui.write("\n }")
def end(self):
baseformatter.end(self)
self._ui.write("\n]\n")
class templateformatter(baseformatter):
def __init__(self, ui, topic, opts):
baseformatter.__init__(self, ui, topic, opts)
self._topic = topic
self._t = gettemplater(ui, topic, opts.get('template', ''))
def _showitem(self):
g = self._t(self._topic, **self._item)
self._ui.write(templater.stringify(g))
def lookuptemplate(ui, topic, tmpl):
# looks like a literal template?
if '{' in tmpl:
return tmpl, None
# perhaps a stock style?
if not os.path.split(tmpl)[0]:
mapname = (templater.templatepath('map-cmdline.' + tmpl)
or templater.templatepath(tmpl))
if mapname and os.path.isfile(mapname):
return None, mapname
# perhaps it's a reference to [templates]
t = ui.config('templates', tmpl)
if t:
try:
tmpl = templater.unquotestring(t)
except SyntaxError:
tmpl = t
return tmpl, None
if tmpl == 'list':
ui.write(_("available styles: %s\n") % templater.stylelist())
raise error.Abort(_("specify a template"))
# perhaps it's a path to a map or a template
if ('/' in tmpl or '\\' in tmpl) and os.path.isfile(tmpl):
# is it a mapfile for a style?
if os.path.basename(tmpl).startswith("map-"):
return None, os.path.realpath(tmpl)
tmpl = open(tmpl).read()
return tmpl, None
# constant string?
return tmpl, None
def gettemplater(ui, topic, spec):
tmpl, mapfile = lookuptemplate(ui, topic, spec)
t = templater.templater(mapfile, {})
if tmpl:
t.cache[topic] = tmpl
return t
def formatter(ui, topic, opts):
template = opts.get("template", "")
if template == "json":
return jsonformatter(ui, topic, opts)
elif template == "pickle":
return pickleformatter(ui, topic, opts)
elif template == "debug":
return debugformatter(ui, topic, opts)
elif template != "":
return templateformatter(ui, topic, opts)
# developer config: ui.formatdebug
elif ui.configbool('ui', 'formatdebug'):
return debugformatter(ui, topic, opts)
# deprecated config: ui.formatjson
elif ui.configbool('ui', 'formatjson'):
return jsonformatter(ui, topic, opts)
return plainformatter(ui, topic, opts)