Mercurial > hg
view mercurial/bundlerepo.py @ 29830:92ac2baaea86
revlog: use an LRU cache for delta chain bases
Profiling using statprof revealed a hotspot during changegroup
application calculating delta chain bases on generaldelta repos.
Essentially, revlog._addrevision() was performing a lot of redundant
work tracing the delta chain as part of determining when the chain
distance was acceptable. This was most pronounced when adding
revisions to manifests, which can have delta chains thousands of
revisions long.
There was a delta chain base cache on revlogs before, but it only
captured a single revision. This was acceptable before generaldelta,
when _addrevision would build deltas from the previous revision and
thus we'd pretty much guarantee a cache hit when resolving the delta
chain base on a subsequent _addrevision call. However, it isn't
suitable for generaldelta because parent revisions aren't necessarily
the last processed revision.
This patch converts the delta chain base cache to an LRU dict cache.
The cache can hold multiple entries, so generaldelta repos have a
higher chance of getting a cache hit.
The impact of this change when processing changegroup additions is
significant. On a generaldelta conversion of the "mozilla-unified"
repo (which contains heads of the main Firefox repositories in
chronological order - this means there are lots of transitions between
heads in revlog order), this change has the following impact when
performing an `hg unbundle` of an uncompressed bundle of the repo:
before: 5:42 CPU time
after: 4:34 CPU time
Most of this time is saved when applying the changelog and manifest
revlogs:
before: 2:30 CPU time
after: 1:17 CPU time
That nearly a 50% reduction in CPU time applying changesets and
manifests!
Applying a gzipped bundle of the same repo (effectively simulating a
`hg clone` over HTTP) showed a similar speedup:
before: 5:53 CPU time
after: 4:46 CPU time
Wall time improvements were basically the same as CPU time.
I didn't measure explicitly, but it feels like most of the time
is saved when processing manifests. This makes sense, as large
manifests tend to have very long delta chains and thus benefit the
most from this cache.
So, this change effectively makes changegroup application (which is
used by `hg unbundle`, `hg clone`, `hg pull`, `hg unshelve`, and
various other commands) significantly faster when delta chains are
long (which can happen on repos with large numbers of files and thus
large manifests).
In theory, this change can result in more memory utilization. However,
we're caching a dict of ints. At most we have 200 ints + Python object
overhead per revlog. And, the cache is really only populated when
performing read-heavy operations, such as adding changegroups or
scanning an individual revlog. For memory bloat to be an issue, we'd
need to scan/read several revisions from several revlogs all while
having active references to several revlogs. I don't think there are
many operations that do this, so I don't think memory bloat from the
cache will be an issue.
author | Gregory Szorc <gregory.szorc@gmail.com> |
---|---|
date | Mon, 22 Aug 2016 21:48:50 -0700 |
parents | 27c0792e834c |
children | bb3281b3fcaa |
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# bundlerepo.py - repository class for viewing uncompressed bundles # # Copyright 2006, 2007 Benoit Boissinot <bboissin@gmail.com> # # This software may be used and distributed according to the terms of the # GNU General Public License version 2 or any later version. """Repository class for viewing uncompressed bundles. This provides a read-only repository interface to bundles as if they were part of the actual repository. """ from __future__ import absolute_import import os import shutil import tempfile from .i18n import _ from .node import nullid from . import ( bundle2, changegroup, changelog, cmdutil, discovery, error, exchange, filelog, localrepo, manifest, mdiff, node as nodemod, pathutil, phases, revlog, scmutil, util, ) class bundlerevlog(revlog.revlog): def __init__(self, opener, indexfile, bundle, linkmapper): # How it works: # To retrieve a revision, we need to know the offset of the revision in # the bundle (an unbundle object). We store this offset in the index # (start). The base of the delta is stored in the base field. # # To differentiate a rev in the bundle from a rev in the revlog, we # check revision against repotiprev. opener = scmutil.readonlyvfs(opener) revlog.revlog.__init__(self, opener, indexfile) self.bundle = bundle n = len(self) self.repotiprev = n - 1 chain = None self.bundlerevs = set() # used by 'bundle()' revset expression getchunk = lambda: bundle.deltachunk(chain) for chunkdata in iter(getchunk, {}): node = chunkdata['node'] p1 = chunkdata['p1'] p2 = chunkdata['p2'] cs = chunkdata['cs'] deltabase = chunkdata['deltabase'] delta = chunkdata['delta'] size = len(delta) start = bundle.tell() - size link = linkmapper(cs) if node in self.nodemap: # this can happen if two branches make the same change chain = node self.bundlerevs.add(self.nodemap[node]) continue for p in (p1, p2): if p not in self.nodemap: raise error.LookupError(p, self.indexfile, _("unknown parent")) if deltabase not in self.nodemap: raise LookupError(deltabase, self.indexfile, _('unknown delta base')) baserev = self.rev(deltabase) # start, size, full unc. size, base (unused), link, p1, p2, node e = (revlog.offset_type(start, 0), size, -1, baserev, link, self.rev(p1), self.rev(p2), node) self.index.insert(-1, e) self.nodemap[node] = n self.bundlerevs.add(n) chain = node n += 1 def _chunk(self, rev): # Warning: in case of bundle, the diff is against what we stored as # delta base, not against rev - 1 # XXX: could use some caching if rev <= self.repotiprev: return revlog.revlog._chunk(self, rev) self.bundle.seek(self.start(rev)) return self.bundle.read(self.length(rev)) def revdiff(self, rev1, rev2): """return or calculate a delta between two revisions""" if rev1 > self.repotiprev and rev2 > self.repotiprev: # hot path for bundle revb = self.index[rev2][3] if revb == rev1: return self._chunk(rev2) elif rev1 <= self.repotiprev and rev2 <= self.repotiprev: return revlog.revlog.revdiff(self, rev1, rev2) return mdiff.textdiff(self.revision(self.node(rev1)), self.revision(self.node(rev2))) def revision(self, nodeorrev): """return an uncompressed revision of a given node or revision number. """ if isinstance(nodeorrev, int): rev = nodeorrev node = self.node(rev) else: node = nodeorrev rev = self.rev(node) if node == nullid: return "" text = None chain = [] iterrev = rev # reconstruct the revision if it is from a changegroup while iterrev > self.repotiprev: if self._cache and self._cache[1] == iterrev: text = self._cache[2] break chain.append(iterrev) iterrev = self.index[iterrev][3] if text is None: text = self.baserevision(iterrev) while chain: delta = self._chunk(chain.pop()) text = mdiff.patches(text, [delta]) self._checkhash(text, node, rev) self._cache = (node, rev, text) return text def baserevision(self, nodeorrev): # Revlog subclasses may override 'revision' method to modify format of # content retrieved from revlog. To use bundlerevlog with such class one # needs to override 'baserevision' and make more specific call here. return revlog.revlog.revision(self, nodeorrev) def addrevision(self, text, transaction, link, p1=None, p2=None, d=None): raise NotImplementedError def addgroup(self, revs, linkmapper, transaction): raise NotImplementedError def strip(self, rev, minlink): raise NotImplementedError def checksize(self): raise NotImplementedError class bundlechangelog(bundlerevlog, changelog.changelog): def __init__(self, opener, bundle): changelog.changelog.__init__(self, opener) linkmapper = lambda x: x bundlerevlog.__init__(self, opener, self.indexfile, bundle, linkmapper) def baserevision(self, nodeorrev): # Although changelog doesn't override 'revision' method, some extensions # may replace this class with another that does. Same story with # manifest and filelog classes. # This bypasses filtering on changelog.node() and rev() because we need # revision text of the bundle base even if it is hidden. oldfilter = self.filteredrevs try: self.filteredrevs = () return changelog.changelog.revision(self, nodeorrev) finally: self.filteredrevs = oldfilter class bundlemanifest(bundlerevlog, manifest.manifest): def __init__(self, opener, bundle, linkmapper, dirlogstarts=None, dir=''): manifest.manifest.__init__(self, opener, dir=dir) bundlerevlog.__init__(self, opener, self.indexfile, bundle, linkmapper) if dirlogstarts is None: dirlogstarts = {} if self.bundle.version == "03": dirlogstarts = _getfilestarts(self.bundle) self._dirlogstarts = dirlogstarts self._linkmapper = linkmapper def baserevision(self, nodeorrev): node = nodeorrev if isinstance(node, int): node = self.node(node) if node in self._mancache: result = self._mancache[node].text() else: result = manifest.manifest.revision(self, nodeorrev) return result def dirlog(self, d): if d in self._dirlogstarts: self.bundle.seek(self._dirlogstarts[d]) return bundlemanifest( self.opener, self.bundle, self._linkmapper, self._dirlogstarts, dir=d) return super(bundlemanifest, self).dirlog(d) class bundlefilelog(bundlerevlog, filelog.filelog): def __init__(self, opener, path, bundle, linkmapper): filelog.filelog.__init__(self, opener, path) bundlerevlog.__init__(self, opener, self.indexfile, bundle, linkmapper) def baserevision(self, nodeorrev): return filelog.filelog.revision(self, nodeorrev) class bundlepeer(localrepo.localpeer): def canpush(self): return False class bundlephasecache(phases.phasecache): def __init__(self, *args, **kwargs): super(bundlephasecache, self).__init__(*args, **kwargs) if util.safehasattr(self, 'opener'): self.opener = scmutil.readonlyvfs(self.opener) def write(self): raise NotImplementedError def _write(self, fp): raise NotImplementedError def _updateroots(self, phase, newroots, tr): self.phaseroots[phase] = newroots self.invalidate() self.dirty = True def _getfilestarts(bundle): bundlefilespos = {} for chunkdata in iter(bundle.filelogheader, {}): fname = chunkdata['filename'] bundlefilespos[fname] = bundle.tell() for chunk in iter(lambda: bundle.deltachunk(None), {}): pass return bundlefilespos class bundlerepository(localrepo.localrepository): def __init__(self, ui, path, bundlename): def _writetempbundle(read, suffix, header=''): """Write a temporary file to disk This is closure because we need to make sure this tracked by self.tempfile for cleanup purposes.""" fdtemp, temp = self.vfs.mkstemp(prefix="hg-bundle-", suffix=".hg10un") self.tempfile = temp with os.fdopen(fdtemp, 'wb') as fptemp: fptemp.write(header) while True: chunk = read(2**18) if not chunk: break fptemp.write(chunk) return self.vfs.open(self.tempfile, mode="rb") self._tempparent = None try: localrepo.localrepository.__init__(self, ui, path) except error.RepoError: self._tempparent = tempfile.mkdtemp() localrepo.instance(ui, self._tempparent, 1) localrepo.localrepository.__init__(self, ui, self._tempparent) self.ui.setconfig('phases', 'publish', False, 'bundlerepo') if path: self._url = 'bundle:' + util.expandpath(path) + '+' + bundlename else: self._url = 'bundle:' + bundlename self.tempfile = None f = util.posixfile(bundlename, "rb") self.bundlefile = self.bundle = exchange.readbundle(ui, f, bundlename) if isinstance(self.bundle, bundle2.unbundle20): cgstream = None for part in self.bundle.iterparts(): if part.type == 'changegroup': if cgstream is not None: raise NotImplementedError("can't process " "multiple changegroups") cgstream = part version = part.params.get('version', '01') legalcgvers = changegroup.supportedincomingversions(self) if version not in legalcgvers: msg = _('Unsupported changegroup version: %s') raise error.Abort(msg % version) if self.bundle.compressed(): cgstream = _writetempbundle(part.read, ".cg%sun" % version) if cgstream is None: raise error.Abort(_('No changegroups found')) cgstream.seek(0) self.bundle = changegroup.getunbundler(version, cgstream, 'UN') elif self.bundle.compressed(): f = _writetempbundle(self.bundle.read, '.hg10un', header='HG10UN') self.bundlefile = self.bundle = exchange.readbundle(ui, f, bundlename, self.vfs) # dict with the mapping 'filename' -> position in the bundle self.bundlefilespos = {} self.firstnewrev = self.changelog.repotiprev + 1 phases.retractboundary(self, None, phases.draft, [ctx.node() for ctx in self[self.firstnewrev:]]) @localrepo.unfilteredpropertycache def _phasecache(self): return bundlephasecache(self, self._phasedefaults) @localrepo.unfilteredpropertycache def changelog(self): # consume the header if it exists self.bundle.changelogheader() c = bundlechangelog(self.svfs, self.bundle) self.manstart = self.bundle.tell() return c @localrepo.unfilteredpropertycache def manifest(self): self.bundle.seek(self.manstart) # consume the header if it exists self.bundle.manifestheader() linkmapper = self.unfiltered().changelog.rev m = bundlemanifest(self.svfs, self.bundle, linkmapper) self.filestart = self.bundle.tell() return m @localrepo.unfilteredpropertycache def manstart(self): self.changelog return self.manstart @localrepo.unfilteredpropertycache def filestart(self): self.manifest return self.filestart def url(self): return self._url def file(self, f): if not self.bundlefilespos: self.bundle.seek(self.filestart) self.bundlefilespos = _getfilestarts(self.bundle) if f in self.bundlefilespos: self.bundle.seek(self.bundlefilespos[f]) linkmapper = self.unfiltered().changelog.rev return bundlefilelog(self.svfs, f, self.bundle, linkmapper) else: return filelog.filelog(self.svfs, f) def close(self): """Close assigned bundle file immediately.""" self.bundlefile.close() if self.tempfile is not None: self.vfs.unlink(self.tempfile) if self._tempparent: shutil.rmtree(self._tempparent, True) def cancopy(self): return False def peer(self): return bundlepeer(self) def getcwd(self): return os.getcwd() # always outside the repo # Check if parents exist in localrepo before setting def setparents(self, p1, p2=nullid): p1rev = self.changelog.rev(p1) p2rev = self.changelog.rev(p2) msg = _("setting parent to node %s that only exists in the bundle\n") if self.changelog.repotiprev < p1rev: self.ui.warn(msg % nodemod.hex(p1)) if self.changelog.repotiprev < p2rev: self.ui.warn(msg % nodemod.hex(p2)) return super(bundlerepository, self).setparents(p1, p2) def instance(ui, path, create): if create: raise error.Abort(_('cannot create new bundle repository')) # internal config: bundle.mainreporoot parentpath = ui.config("bundle", "mainreporoot", "") if not parentpath: # try to find the correct path to the working directory repo parentpath = cmdutil.findrepo(os.getcwd()) if parentpath is None: parentpath = '' if parentpath: # Try to make the full path relative so we get a nice, short URL. # In particular, we don't want temp dir names in test outputs. cwd = os.getcwd() if parentpath == cwd: parentpath = '' else: cwd = pathutil.normasprefix(cwd) if parentpath.startswith(cwd): parentpath = parentpath[len(cwd):] u = util.url(path) path = u.localpath() if u.scheme == 'bundle': s = path.split("+", 1) if len(s) == 1: repopath, bundlename = parentpath, s[0] else: repopath, bundlename = s else: repopath, bundlename = parentpath, path return bundlerepository(ui, repopath, bundlename) class bundletransactionmanager(object): def transaction(self): return None def close(self): raise NotImplementedError def release(self): raise NotImplementedError def getremotechanges(ui, repo, other, onlyheads=None, bundlename=None, force=False): '''obtains a bundle of changes incoming from other "onlyheads" restricts the returned changes to those reachable from the specified heads. "bundlename", if given, stores the bundle to this file path permanently; otherwise it's stored to a temp file and gets deleted again when you call the returned "cleanupfn". "force" indicates whether to proceed on unrelated repos. Returns a tuple (local, csets, cleanupfn): "local" is a local repo from which to obtain the actual incoming changesets; it is a bundlerepo for the obtained bundle when the original "other" is remote. "csets" lists the incoming changeset node ids. "cleanupfn" must be called without arguments when you're done processing the changes; it closes both the original "other" and the one returned here. ''' tmp = discovery.findcommonincoming(repo, other, heads=onlyheads, force=force) common, incoming, rheads = tmp if not incoming: try: if bundlename: os.unlink(bundlename) except OSError: pass return repo, [], other.close commonset = set(common) rheads = [x for x in rheads if x not in commonset] bundle = None bundlerepo = None localrepo = other.local() if bundlename or not localrepo: # create a bundle (uncompressed if other repo is not local) # developer config: devel.legacy.exchange legexc = ui.configlist('devel', 'legacy.exchange') forcebundle1 = 'bundle2' not in legexc and 'bundle1' in legexc canbundle2 = (not forcebundle1 and other.capable('getbundle') and other.capable('bundle2')) if canbundle2: kwargs = {} kwargs['common'] = common kwargs['heads'] = rheads kwargs['bundlecaps'] = exchange.caps20to10(repo) kwargs['cg'] = True b2 = other.getbundle('incoming', **kwargs) fname = bundle = changegroup.writechunks(ui, b2._forwardchunks(), bundlename) else: if other.capable('getbundle'): cg = other.getbundle('incoming', common=common, heads=rheads) elif onlyheads is None and not other.capable('changegroupsubset'): # compat with older servers when pulling all remote heads cg = other.changegroup(incoming, "incoming") rheads = None else: cg = other.changegroupsubset(incoming, rheads, 'incoming') if localrepo: bundletype = "HG10BZ" else: bundletype = "HG10UN" fname = bundle = bundle2.writebundle(ui, cg, bundlename, bundletype) # keep written bundle? if bundlename: bundle = None if not localrepo: # use the created uncompressed bundlerepo localrepo = bundlerepo = bundlerepository(repo.baseui, repo.root, fname) # this repo contains local and other now, so filter out local again common = repo.heads() if localrepo: # Part of common may be remotely filtered # So use an unfiltered version # The discovery process probably need cleanup to avoid that localrepo = localrepo.unfiltered() csets = localrepo.changelog.findmissing(common, rheads) if bundlerepo: reponodes = [ctx.node() for ctx in bundlerepo[bundlerepo.firstnewrev:]] remotephases = other.listkeys('phases') pullop = exchange.pulloperation(bundlerepo, other, heads=reponodes) pullop.trmanager = bundletransactionmanager() exchange._pullapplyphases(pullop, remotephases) def cleanup(): if bundlerepo: bundlerepo.close() if bundle: os.unlink(bundle) other.close() return (localrepo, csets, cleanup)