view hgweb.cgi @ 42480:66c27df1be84

deltas: skip if projected delta size is bigger than previous snapshot

Before computing any delta, we get a basic estimation of the delta size we can
expect and the resulted compressed value. We then checks this projected size
against the `size(snapshotⁿ) > size(snapshotⁿ⁺¹)` constraint. This allows to
exclude potential base candidates before doing any expensive computation.

This only apply to the intermediate-snapshot case since this constraint only
apply to them.

For some pathological cases of a private repository this step provide a
significant performance boost (timing from `hg perfrevlogwrite`):

before: 14.115908 seconds
after:   3.145906 seconds

#!/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)