changegroup: don't try to build changelog chunks if not required
When we extend a narrow clone without ellipsis, we don't download changelog
information because that's already present with the client. However we still try
to build that chunk stream. Building that chunk stream involves calling a lookup
function and store.emitrevisions() API. The lookup function is called len(cl)
number of times.
On large repositories, where len(cl) is in millions, calling that lookup
function is not a good idea. Also it's not required to use the
store.emitrevisons() API because we already have nodes present which we can use.
This patch short-circuits state building logic if we are processing a
non-ellipsis case and changelog is not required.
This saves up ~20 seconds on our internal repo for a single extend call.
Differential Revision: https://phab.mercurial-scm.org/D5733
#!/usr/bin/env python
#
# An example hgweb CGI script, edit as necessary
# See also https://mercurial-scm.org/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)