lock: fixed race condition in trylock/testlock (issue3506)
Suppose the following scenario:
1. Process A takes the lock (e.g. on commit).
2. Process B wants to grab the lock. Since lock file exists
the exception is raised. In the catch block the testlock
function is called.
3. Process A releases the lock.
4. Process B tries to read the lock file as a part of testlock
function. This results in OSError (ENOENT) and since we're
not inside the exception handler function this is propagated
and aborts the whole operation.
To fix this we now check in testlock function whether lock file
actually exists and if not (i.e. if readlock fails) we just return.
#!/usr/bin/env python
#
# An example hgweb CGI script, edit as necessary
# See also http://mercurial.selenic.com/wiki/PublishingRepositories
# Path to repo or hgweb config to serve (see 'hg help hgweb')
config = "/path/to/repo/or/config"
# Uncomment and adjust if Mercurial is not installed system-wide
# (consult "installed modules" path from 'hg debuginstall'):
#import sys; sys.path.insert(0, "/path/to/python/lib")
# Uncomment to send python tracebacks to the browser if an error occurs:
#import cgitb; cgitb.enable()
from mercurial import demandimport; demandimport.enable()
from mercurial.hgweb import hgweb, wsgicgi
application = hgweb(config)
wsgicgi.launch(application)