view mercurial/treediscovery.py @ 46335:25be21ec6c65

share: rework config options to be much clearer and easier

Recently I implemented various boolean configs which control how to behave when
there is a share-safe mismatch between source and share repository. Mismatch
means that source supports share-safe where as share does not or vice versa.

However, while discussion and documentation we realized that it's too
complicated and there are some combinations of values which makes no sense.

We decided to introduce a config option with 4 possible values which
makes controlling and understanding things easier.

The config option `share.safe-mismatch.source-{not-}safe` can have
following 4 values:

* abort (default): error out if there is mismatch
* allow: allow to work with respecting share source configuration
* {up|down}grade-abort: try to {up|down}grade, if it fails, abort
* {up|down}grade-allow: try to {up|down}grade, if it fails, continue in allow
mode


I am not sure if I can explain 3 config options which I deleted right now in
just 5 lines which is a sign of how complex they became.

No test changes demonstrate that functionality is same, only names have changed.

Differential Revision: https://phab.mercurial-scm.org/D9785

# discovery.py - protocol changeset discovery functions
#
# Copyright 2010 Matt 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.

from __future__ import absolute_import

import collections

from .i18n import _
from .node import (
    nullid,
    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

    if repo.changelog.tip() == nullid:
        base.add(nullid)
        if heads != [nullid]:
            return [nullid], [nullid], list(heads)
        return [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:
        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] == 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:
                    branches = e.callcommand(
                        b'branches',
                        {
                            b'nodes': r[p : p + 10],
                        },
                    ).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:
            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 == [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