view hgext/narrow/narrowwirepeer.py @ 44363:f7459da77f23

nodemap: introduce an option to use mmap to read the nodemap mapping

The performance and memory benefit is much greater if we don't have to copy all
the data in memory for each information. So we introduce an option (on by
default) to read the data using mmap.

This changeset is the last one definition the API for index support nodemap
data. (they have to be able to use the mmaping).

Below are some benchmark comparing the best we currently have in 5.3 with the
final step of this series (using the persistent nodemap implementation in
Rust). The benchmark run `hg perfindex` with various revset and the following
variants:

Before:

 * do not use the persistent nodemap
 * use the CPython implementation of the index for nodemap
 * use mmapping of the changelog index

After:

 * use the MixedIndex Rust code, with the NodeTree object for nodemap access
   (still in review)
 * use the persistent nodemap data from disk
 * access the persistent nodemap data through mmap
 * use mmapping of the changelog index

The persistent nodemap greatly speed up  most operation on very large
repositories. Some of the previously very fast lookup end up a bit slower because
the persistent nodemap has to be setup. However the absolute slowdown is very
small and won't matters in the big picture.

Here are some numbers (in seconds) for the reference copy of mozilla-try:

Revset            Before   After     abs-change speedup

-10000:           0.004622 0.005532   0.000910  ×   0.83
-10:              0.000050 0.000132   0.000082  ×   0.37
tip               0.000052 0.000085   0.000033  ×   0.61
0 + (-10000:)     0.028222 0.005337  -0.022885  ×   5.29
0                 0.023521 0.000084  -0.023437  × 280.01
(-10000:) + 0     0.235539 0.005308  -0.230231  ×  44.37
(-10:) + :9       0.232883 0.000180  -0.232703  ×1293.79
(-10000:) + (:99) 0.238735 0.005358  -0.233377  ×  44.55
:99 + (-10000:)   0.317942 0.005593  -0.312349  ×  56.84
:9 + (-10:)       0.313372 0.000179  -0.313193  ×1750.68
:9                0.316450 0.000143  -0.316307  ×2212.93


On smaller repositories, the cost of nodemap related operation is not as big, so
the win is much more modest. Yet it helps shaving a handful of millisecond here
and there.

Here are some numbers (in seconds) for the reference copy of mercurial:

Revset            Before   After     abs-change speedup
-10:              0.000065 0.000097   0.000032  × 0.67
tip               0.000063 0.000078   0.000015  × 0.80
0                 0.000561 0.000079  -0.000482  × 7.10
-10000:           0.004609 0.003648  -0.000961  × 1.26
0 + (-10000:)     0.005023 0.003715  -0.001307  × 1.35
(-10:) + :9       0.002187 0.000108  -0.002079  ×20.25
(-10000:) + 0     0.006252 0.003716  -0.002536  × 1.68
(-10000:) + (:99) 0.006367 0.003707  -0.002660  × 1.71
:9 + (-10:)       0.003846 0.000110  -0.003736  ×34.96
:9                0.003854 0.000099  -0.003755  ×38.92
:99 + (-10000:)   0.007644 0.003778  -0.003866  × 2.02

Differential Revision: https://phab.mercurial-scm.org/D7894

# narrowwirepeer.py - passes narrow spec with unbundle command
#
# Copyright 2017 Google, Inc.
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

from __future__ import absolute_import

from mercurial import (
    bundle2,
    error,
    extensions,
    hg,
    narrowspec,
    pycompat,
    wireprototypes,
    wireprotov1peer,
    wireprotov1server,
)

from . import narrowbundle2


def uisetup():
    wireprotov1peer.wirepeer.narrow_widen = peernarrowwiden


def reposetup(repo):
    def wirereposetup(ui, peer):
        def wrapped(orig, cmd, *args, **kwargs):
            if cmd == b'unbundle':
                # TODO: don't blindly add include/exclude wireproto
                # arguments to unbundle.
                include, exclude = repo.narrowpats
                kwargs["includepats"] = b','.join(include)
                kwargs["excludepats"] = b','.join(exclude)
            return orig(cmd, *args, **kwargs)

        extensions.wrapfunction(peer, b'_calltwowaystream', wrapped)

    hg.wirepeersetupfuncs.append(wirereposetup)


@wireprotov1server.wireprotocommand(
    b'narrow_widen',
    b'oldincludes oldexcludes'
    b' newincludes newexcludes'
    b' commonheads cgversion'
    b' known ellipses',
    permission=b'pull',
)
def narrow_widen(
    repo,
    proto,
    oldincludes,
    oldexcludes,
    newincludes,
    newexcludes,
    commonheads,
    cgversion,
    known,
    ellipses,
):
    """wireprotocol command to send data when a narrow clone is widen. We will
    be sending a changegroup here.

    The current set of arguments which are required:
    oldincludes: the old includes of the narrow copy
    oldexcludes: the old excludes of the narrow copy
    newincludes: the new includes of the narrow copy
    newexcludes: the new excludes of the narrow copy
    commonheads: list of heads which are common between the server and client
    cgversion(maybe): the changegroup version to produce
    known: list of nodes which are known on the client (used in ellipses cases)
    ellipses: whether to send ellipses data or not
    """

    preferuncompressed = False
    try:

        def splitpaths(data):
            # work around ''.split(',') => ['']
            return data.split(b',') if data else []

        oldincludes = splitpaths(oldincludes)
        newincludes = splitpaths(newincludes)
        oldexcludes = splitpaths(oldexcludes)
        newexcludes = splitpaths(newexcludes)
        # validate the patterns
        narrowspec.validatepatterns(set(oldincludes))
        narrowspec.validatepatterns(set(newincludes))
        narrowspec.validatepatterns(set(oldexcludes))
        narrowspec.validatepatterns(set(newexcludes))

        common = wireprototypes.decodelist(commonheads)
        known = wireprototypes.decodelist(known)
        if ellipses == b'0':
            ellipses = False
        else:
            ellipses = bool(ellipses)
        cgversion = cgversion

        bundler = bundle2.bundle20(repo.ui)
        newmatch = narrowspec.match(
            repo.root, include=newincludes, exclude=newexcludes
        )
        oldmatch = narrowspec.match(
            repo.root, include=oldincludes, exclude=oldexcludes
        )
        if not ellipses:
            bundle2.widen_bundle(
                bundler,
                repo,
                oldmatch,
                newmatch,
                common,
                known,
                cgversion,
                ellipses,
            )
        else:
            narrowbundle2.generate_ellipses_bundle2_for_widening(
                bundler, repo, oldmatch, newmatch, cgversion, common, known,
            )
    except error.Abort as exc:
        bundler = bundle2.bundle20(repo.ui)
        manargs = [(b'message', pycompat.bytestr(exc))]
        advargs = []
        if exc.hint is not None:
            advargs.append((b'hint', exc.hint))
        bundler.addpart(bundle2.bundlepart(b'error:abort', manargs, advargs))
        preferuncompressed = True

    chunks = bundler.getchunks()
    return wireprototypes.streamres(
        gen=chunks, prefer_uncompressed=preferuncompressed
    )


def peernarrowwiden(remote, **kwargs):
    for ch in ('commonheads', 'known'):
        kwargs[ch] = wireprototypes.encodelist(kwargs[ch])

    for ch in ('oldincludes', 'newincludes', 'oldexcludes', 'newexcludes'):
        kwargs[ch] = b','.join(kwargs[ch])

    kwargs['ellipses'] = b'%i' % bool(kwargs['ellipses'])
    f = remote._callcompressable(b'narrow_widen', **kwargs)
    return bundle2.getunbundler(remote.ui, f)