annotate hgext/fastannotate/__init__.py @ 39210:1ddb296e0dee

fastannotate: initial import from Facebook's hg-experimental

I made as few changes as I could to get the tests to pass, but this
was a bit involved due to some churn in the blame code since someone
last gave fastannotate any TLC.

There's still follow-up work here to rip out support for old versions
of hg and to integrate the protocol with modern standards.

Some performance numbers (all on my 2016 MacBook Pro with a 2.6Ghz i7):

Mercurial mercurial/manifest.py
traditional blame
time: real 1.050 secs (user 0.990+0.000 sys 0.060+0.000)
build cache
time: real 5.900 secs (user 5.720+0.000 sys 0.110+0.000)
fastannotate
time: real 0.120 secs (user 0.100+0.000 sys 0.020+0.000)

Mercurial mercurial/localrepo.py
traditional blame
time: real 3.330 secs (user 3.220+0.000 sys 0.070+0.000)
build cache
time: real 30.610 secs (user 30.190+0.000 sys 0.230+0.000)
fastannotate
time: real 0.180 secs (user 0.160+0.000 sys 0.020+0.000)

mozilla-central dom/ipc/ContentParent.cpp
traditional blame
time: real 7.640 secs (user 7.210+0.000 sys 0.380+0.000)
build cache
time: real 98.650 secs (user 97.000+0.000 sys 0.950+0.000)
fastannotate
time: real 1.580 secs (user 1.340+0.000 sys 0.240+0.000)

mozilla-central dom/base/nsDocument.cpp
traditional blame
time: real 17.110 secs (user 16.490+0.000 sys 0.500+0.000)
build cache
time: real 399.750 secs (user 394.520+0.000 sys 2.610+0.000)
fastannotate
time: real 1.780 secs (user 1.530+0.000 sys 0.240+0.000)

So building the cache is expensive (but might be faster with xdiff
enabled), but the blame results are *way* faster.

Differential Revision: https://phab.mercurial-scm.org/D3994

# Copyright 2016-present Facebook. All Rights Reserved.
#
# fastannotate: faster annotate implementation using linelog
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
"""yet another annotate implementation that might be faster (EXPERIMENTAL)

The fastannotate extension provides a 'fastannotate' command that makes
use of the linelog data structure as a cache layer and is expected to
be faster than the vanilla 'annotate' if the cache is present.

In most cases, fastannotate requires a setup that mainbranch is some pointer
that always moves forward, to be most efficient.

Using fastannotate together with linkrevcache would speed up building the
annotate cache greatly. Run "debugbuildlinkrevcache" before
"debugbuildannotatecache".

::

    [fastannotate]
    # specify the main branch head. the internal linelog will only contain
    # the linear (ignoring p2) "mainbranch". since linelog cannot move
    # backwards without a rebuild, this should be something that always moves
    # forward, usually it is "master" or "@".
    mainbranch = master

    # fastannotate supports different modes to expose its feature.
    # a list of combination:
    # - fastannotate: expose the feature via the "fastannotate" command which
    #   deals with everything in a most efficient way, and provides extra
    #   features like --deleted etc.
    # - fctx: replace fctx.annotate implementation. note:
    #     a. it is less efficient than the "fastannotate" command
    #     b. it will make it practically impossible to access the old (disk
    #        side-effect free) annotate implementation
    #     c. it implies "hgweb".
    # - hgweb: replace hgweb's annotate implementation. conflict with "fctx".
    # (default: fastannotate)
    modes = fastannotate

    # default format when no format flags are used (default: number)
    defaultformat = changeset, user, date

    # serve the annotate cache via wire protocol (default: False)
    # tip: the .hg/fastannotate directory is portable - can be rsynced
    server = True

    # build annotate cache on demand for every client request (default: True)
    # disabling it could make server response faster, useful when there is a
    # cronjob building the cache.
    serverbuildondemand = True

    # update local annotate cache from remote on demand
    # (default: True for remotefilelog repo, False otherwise)
    client = True

    # path to use when connecting to the remote server (default: default)
    remotepath = default

    # share sshpeer with remotefilelog. this would allow fastannotate to peek
    # into remotefilelog internals, and steal its sshpeer, or in the reversed
    # direction: donate its sshpeer to remotefilelog. disable this if
    # fastannotate and remotefilelog should not share a sshpeer when their
    # endpoints are different and incompatible. (default: True)
    clientsharepeer = True

    # minimal length of the history of a file required to fetch linelog from
    # the server. (default: 10)
    clientfetchthreshold = 10

    # use flock instead of the file existence lock
    # flock may not work well on some network filesystems, but they avoid
    # creating and deleting files frequently, which is faster when updating
    # the annotate cache in batch. if you have issues with this option, set it
    # to False. (default: True if flock is supported, False otherwise)
    useflock = True

    # for "fctx" mode, always follow renames regardless of command line option.
    # this is a BC with the original command but will reduced the space needed
    # for annotate cache, and is useful for client-server setup since the
    # server will only provide annotate cache with default options (i.e. with
    # follow). do not affect "fastannotate" mode. (default: True)
    forcefollow = True

    # for "fctx" mode, always treat file as text files, to skip the "isbinary"
    # check. this is consistent with the "fastannotate" command and could help
    # to avoid a file fetch if remotefilelog is used. (default: True)
    forcetext = True

    # use unfiltered repo for better performance.
    unfilteredrepo = True

    # sacrifice correctness in some corner cases for performance. it does not
    # affect the correctness of the annotate cache being built. the option
    # is experimental and may disappear in the future (default: False)
    perfhack = True
"""

from __future__ import absolute_import

from mercurial.i18n import _
from mercurial import (
    error as hgerror,
    localrepo,
    registrar,
    util,
)

from . import (
    commands,
    context,
    protocol,
)

# 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'

cmdtable = commands.cmdtable

configtable = {}
configitem = registrar.configitem(configtable)

configitem('fastannotate', 'modes', default=['fastannotate'])
configitem('fastannotate', 'server', default=False)
configitem('fastannotate', 'useflock', default=True)
configitem('fastannotate', 'client')
configitem('fastannotate', 'unfilteredrepo', default=True)
configitem('fastannotate', 'defaultformat', default=['number'])
configitem('fastannotate', 'perfhack', default=False)
configitem('fastannotate', 'mainbranch')
configitem('fastannotate', 'forcetext', default=True)
configitem('fastannotate', 'forcefollow', default=True)
configitem('fastannotate', 'clientfetchthreshold', default=10)
configitem('fastannotate', 'clientsharepeer', default=True)
configitem('fastannotate', 'serverbuildondemand', default=True)
configitem('fastannotate', 'remotepath', default='default')

def _flockavailable():
    try:
        import fcntl
        fcntl.flock
    except StandardError:
        return False
    else:
        return True

def uisetup(ui):
    modes = set(ui.configlist('fastannotate', 'modes'))
    if 'fctx' in modes:
        modes.discard('hgweb')
    for name in modes:
        if name == 'fastannotate':
            commands.registercommand()
        elif name == 'hgweb':
            from . import support
            support.replacehgwebannotate()
        elif name == 'fctx':
            from . import support
            support.replacefctxannotate()
            support.replaceremotefctxannotate()
            commands.wrapdefault()
        else:
            raise hgerror.Abort(_('fastannotate: invalid mode: %s') % name)

    if ui.configbool('fastannotate', 'server'):
        protocol.serveruisetup(ui)

    if ui.configbool('fastannotate', 'useflock', _flockavailable()):
        context.pathhelper.lock = context.pathhelper._lockflock

    # fastannotate has its own locking, without depending on repo lock
    localrepo.localrepository._wlockfreeprefix.add('fastannotate/')

def reposetup(ui, repo):
    client = ui.configbool('fastannotate', 'client', default=None)
    if client is None:
        if util.safehasattr(repo, 'requirements'):
            client = 'remotefilelog' in repo.requirements
    if client:
        protocol.clientreposetup(ui, repo)