view mercurial/treediscovery.py @ 49017:f054a557aab8

discovery: also audit the number of queries done

In addition to the number of roundtrip, we now also track the number of queries
we perform, this is useful to assert the tradeoff between number of roundtrip and
the number of queries.

Differential Revision: https://phab.mercurial-scm.org/D12398

# discovery.py - protocol changeset discovery functions
#
# Copyright 2010 Olivia Mackall <[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.


import collections

from .i18n import _
from .node import short
from . import (
    error,
    pycompat,
)


def findcommonincoming(repo, remote, heads=None, force=False, audit=None):
    """Return a tuple (common, fetch, heads) used to identify the common
    subset of nodes between repo and remote.

    "common" is a list of (at least) the heads of the common subset.
    "fetch" is a list of roots of the nodes that would be incoming, to be
      supplied to changegroupsubset.
    "heads" is either the supplied heads, or else the remote's heads.
    """

    knownnode = repo.changelog.hasnode
    search = []
    fetch = set()
    seen = set()
    seenbranch = set()
    base = set()

    if not heads:
        with remote.commandexecutor() as e:
            heads = e.callcommand(b'heads', {}).result()

    if audit is not None:
        audit[b'total-roundtrips'] = 1
        audit[b'total-queries'] = 0

    if repo.changelog.tip() == repo.nullid:
        base.add(repo.nullid)
        if heads != [repo.nullid]:
            return [repo.nullid], [repo.nullid], list(heads)
        return [repo.nullid], [], heads

    # assume we're closer to the tip than the root
    # and start by examining the heads
    repo.ui.status(_(b"searching for changes\n"))

    unknown = []
    for h in heads:
        if not knownnode(h):
            unknown.append(h)
        else:
            base.add(h)

    if not unknown:
        return list(base), [], list(heads)

    req = set(unknown)
    reqcnt = 0
    progress = repo.ui.makeprogress(_(b'searching'), unit=_(b'queries'))

    # search through remote branches
    # a 'branch' here is a linear segment of history, with four parts:
    # head, root, first parent, second parent
    # (a branch always has two parents (or none) by definition)
    with remote.commandexecutor() as e:
        if audit is not None:
            audit[b'total-queries'] += len(unknown)
        branches = e.callcommand(b'branches', {b'nodes': unknown}).result()

    unknown = collections.deque(branches)
    while unknown:
        r = []
        while unknown:
            n = unknown.popleft()
            if n[0] in seen:
                continue

            repo.ui.debug(b"examining %s:%s\n" % (short(n[0]), short(n[1])))
            if n[0] == repo.nullid:  # found the end of the branch
                pass
            elif n in seenbranch:
                repo.ui.debug(b"branch already found\n")
                continue
            elif n[1] and knownnode(n[1]):  # do we know the base?
                repo.ui.debug(
                    b"found incomplete branch %s:%s\n"
                    % (short(n[0]), short(n[1]))
                )
                search.append(n[0:2])  # schedule branch range for scanning
                seenbranch.add(n)
            else:
                if n[1] not in seen and n[1] not in fetch:
                    if knownnode(n[2]) and knownnode(n[3]):
                        repo.ui.debug(b"found new changeset %s\n" % short(n[1]))
                        fetch.add(n[1])  # earliest unknown
                    for p in n[2:4]:
                        if knownnode(p):
                            base.add(p)  # latest known

                for p in n[2:4]:
                    if p not in req and not knownnode(p):
                        r.append(p)
                        req.add(p)
            seen.add(n[0])

        if r:
            reqcnt += 1
            progress.increment()
            repo.ui.debug(
                b"request %d: %s\n" % (reqcnt, b" ".join(map(short, r)))
            )
            for p in pycompat.xrange(0, len(r), 10):
                with remote.commandexecutor() as e:
                    subset = r[p : p + 10]
                    if audit is not None:
                        audit[b'total-queries'] += len(subset)
                    branches = e.callcommand(
                        b'branches',
                        {
                            b'nodes': subset,
                        },
                    ).result()

                for b in branches:
                    repo.ui.debug(
                        b"received %s:%s\n" % (short(b[0]), short(b[1]))
                    )
                    unknown.append(b)

    # do binary search on the branches we found
    while search:
        newsearch = []
        reqcnt += 1
        progress.increment()

        with remote.commandexecutor() as e:
            if audit is not None:
                audit[b'total-queries'] += len(search)
            between = e.callcommand(b'between', {b'pairs': search}).result()

        for n, l in zip(search, between):
            l.append(n[1])
            p = n[0]
            f = 1
            for i in l:
                repo.ui.debug(b"narrowing %d:%d %s\n" % (f, len(l), short(i)))
                if knownnode(i):
                    if f <= 2:
                        repo.ui.debug(
                            b"found new branch changeset %s\n" % short(p)
                        )
                        fetch.add(p)
                        base.add(i)
                    else:
                        repo.ui.debug(
                            b"narrowed branch search to %s:%s\n"
                            % (short(p), short(i))
                        )
                        newsearch.append((p, i))
                    break
                p, f = i, f * 2
            search = newsearch

    # sanity check our fetch list
    for f in fetch:
        if knownnode(f):
            raise error.RepoError(_(b"already have changeset ") + short(f[:4]))

    base = list(base)
    if base == [repo.nullid]:
        if force:
            repo.ui.warn(_(b"warning: repository is unrelated\n"))
        else:
            raise error.Abort(_(b"repository is unrelated"))

    repo.ui.debug(
        b"found new changesets starting at "
        + b" ".join([short(f) for f in fetch])
        + b"\n"
    )

    progress.complete()
    repo.ui.debug(b"%d total queries\n" % reqcnt)
    if audit is not None:
        audit[b'total-roundtrips'] = reqcnt

    return base, list(fetch), heads