Mercurial > hg
view mercurial/treediscovery.py @ 45059:79f6f9fa18c1
documentation: add some internals documentation about bid merge
This is an important algorithm that was only documented on the wiki so far.
Some update to the algorithm (and associated doc) is to expected in the future
since the bid merge algorithm is bug-ridden when it comes to file deletion comes
to play.
Differential Revision: https://phab.mercurial-scm.org/D8711
author | Pierre-Yves David <pierre-yves.david@octobus.net> |
---|---|
date | Mon, 22 Jun 2020 13:32:20 +0200 |
parents | 687b865b95ad |
children | 89a2afe31e82 |
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# discovery.py - protocol changeset discovery functions # # Copyright 2010 Matt Mackall <mpm@selenic.com> # # 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): """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 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) return base, list(fetch), heads