view hgext/children.py @ 30289:1f92056c4066

revlog: optimize _chunkraw when startrev==endrev

In many cases, _chunkraw() is called with startrev==endrev. When
this is true, we can avoid an extra index lookup and some other
minor operations.

On the mozilla-unified repo, `hg perfrevlogchunks -c` says this
has the following impact:

! read w/ reused fd
! wall 0.371846 comb 0.370000 user 0.350000 sys 0.020000 (best of 27)
! wall 0.337930 comb 0.330000 user 0.300000 sys 0.030000 (best of 30)

! read batch w/ reused fd
! wall 0.014952 comb 0.020000 user 0.000000 sys 0.020000 (best of 197)
! wall 0.014866 comb 0.010000 user 0.000000 sys 0.010000 (best of 196)

So, we've gone from ~25x slower than batch to ~22.5x slower.

At this point, there's probably not much else we can do except
implement an optimized function in the index itself, including in C.

# Mercurial extension to provide the 'hg children' command
#
# Copyright 2007 by Intevation GmbH <[e-mail]>
#
# Author(s):
# Thomas Arendsen Hein <[e-mail]>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

'''command to display child changesets (DEPRECATED)

This extension is deprecated. You should use :hg:`log -r
"children(REV)"` instead.
'''

from __future__ import absolute_import

from mercurial.i18n import _
from mercurial import (
    cmdutil,
    commands,
)

templateopts = commands.templateopts

cmdtable = {}
command = cmdutil.command(cmdtable)
# Note for extension authors: ONLY specify testedwith = 'ships-with-hg-core' for
# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
# be specifying the version(s) of Mercurial they are tested with, or
# leave the attribute unspecified.
testedwith = 'ships-with-hg-core'

@command('children',
    [('r', 'rev', '',
     _('show children of the specified revision'), _('REV')),
    ] + templateopts,
    _('hg children [-r REV] [FILE]'),
    inferrepo=True)
def children(ui, repo, file_=None, **opts):
    """show the children of the given or working directory revision

    Print the children of the working directory's revisions. If a
    revision is given via -r/--rev, the children of that revision will
    be printed. If a file argument is given, revision in which the
    file was last changed (after the working directory revision or the
    argument to --rev if given) is printed.

    Please use :hg:`log` instead::

        hg children => hg log -r "children()"
        hg children -r REV => hg log -r "children(REV)"

    See :hg:`help log` and :hg:`help revsets.children`.

    """
    rev = opts.get('rev')
    if file_:
        fctx = repo.filectx(file_, changeid=rev)
        childctxs = [fcctx.changectx() for fcctx in fctx.children()]
    else:
        ctx = repo[rev]
        childctxs = ctx.children()

    displayer = cmdutil.show_changeset(ui, repo, opts)
    for cctx in childctxs:
        displayer.show(cctx)
    displayer.close()