view tests/test-hgwebdir-paths.py @ 17970:0b03454abae7

ancestor: faster algorithm for difference of ancestor sets

One of the major reasons rebase is slow in large repositories is
the computation of the detach set: the set of ancestors of the
changesets to rebase not in the destination parent. This is currently
done via a revset that does two walks all the way to the root of
the DAG. Instead of doing that, to find ancestors of a set <revs>
not in another set <common> we walk up the tree in reverse revision
number order, maintaining sets of nodes visited from <revs>, <common>
or both.

For the common case where the sets are close both topologically and
in revision number (relative to repository size), this has been
found to speed up rebase by around 15-20%. When the nodes are farther
apart and the DAG is highly branching, it is harder to say which
would win.

Here's how long computing the detach set takes in a linear repository
with over 400000 changesets, rebasing near tip:

Rebasing across 4 changesets
Revset method: 2.2s
New algorithm: 0.00015s

Rebasing across 250 changesets
Revset method: 2.2s
New algorithm: 0.00069s

Rebasing across 10000 changesets
Revset method: 2.4s
New algorithm: 0.019s

import os
from mercurial import hg, ui
from mercurial.hgweb.hgwebdir_mod import hgwebdir

os.mkdir('webdir')
os.chdir('webdir')

webdir = os.path.realpath('.')

u = ui.ui()
hg.repository(u, 'a', create=1)
hg.repository(u, 'b', create=1)
os.chdir('b')
hg.repository(u, 'd', create=1)
os.chdir('..')
hg.repository(u, 'c', create=1)
os.chdir('..')

paths = {'t/a/': '%s/a' % webdir,
         'b': '%s/b' % webdir,
         'coll': '%s/*' % webdir,
         'rcoll': '%s/**' % webdir}

config = os.path.join(webdir, 'hgwebdir.conf')
configfile = open(config, 'w')
configfile.write('[paths]\n')
for k, v in paths.items():
    configfile.write('%s = %s\n' % (k, v))
configfile.close()

confwd = hgwebdir(config)
dictwd = hgwebdir(paths)

assert len(confwd.repos) == len(dictwd.repos), 'different numbers'
assert len(confwd.repos) == 9, 'expected 9 repos, found %d' % len(confwd.repos)

found = dict(confwd.repos)
for key, path in dictwd.repos:
    assert key in found, 'repository %s was not found' % key
    assert found[key] == path, 'different paths for repo %s' % key