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Differential D4491

exchangev2: fetch file revisions
ClosedPublic

Authored by indygreg on Sep 5 2018, 12:20 PM.

Details

Reviewers
durin42
Group Reviewers
hg-reviewers
Commits
rHG039bf1eddc2e: exchangev2: fetch file revisions
Summary

Now that the server has an API for fetching file data, we can call into
it to fetch file revisions.

The implementation is relatively straightforward: we examine the
manifests that we fetched and find all new file revisions referenced
by them. We build up a mapping from file path to file nodes to
manifest node. (The mapping to first manifest node allows us to
map back to first changelog node/revision, which is used for the
linkrev.)

Once that map is built up, we iterate over it in a deterministic
manner and fetch and store file data. The code is very similar
to manifest fetching. So similar that we could probably extract the
common bits into a generic function.

With file data retrieval implemented, hg clone and hg pull are
effectively feature complete, at least as far as the completeness
of data transfer for essential repository data (changesets, manifests,
files, phases, and bookmarks). We're still missing support for
obsolescence markers, the hgtags fnodes cache, and the branchmap
cache. But these are non-essential for the moment (and will be
implemented later).

This is a good point to assess the state of exchangev2 in terms of
performance. I ran a local hg clone for the mozilla-unified
repository using both version 1 and version 2 of the wire protocols
and exchange methods. This is effectively comparing the performance
of the wire protocol overhead and "getbundle" versus domain-specific
commands. Wire protocol version 2 doesn't have compression implemented
yet. So I tested version 1 with server.compressionengines=none to
remove compression overhead from the equation.

server
before: user 220.420+0.000 sys 14.420+0.000
after: user 321.980+0.000 sys 18.990+0.000

client
before: real 561.650 secs (user 497.670+0.000 sys 28.160+0.000)
after: real 1226.260 secs (user 944.240+0.000 sys 354.150+0.000)

We have substantial regressions on both client and server. This
is obviously not desirable. I'm aware of some reasons:

  • Lack of hgtagsfnodes transfer (contributes significant CPU to client).
  • Lack of branch cache transfer (contributes significant CPU to client).
  • Little to no profiling / optimization performed on wire protocol version 2 code.
  • There appears to be a memory leak on the client and that is likely causing swapping on my machine.
  • Using multiple threads on the client may be counter-productive because Python.
  • We're not compressing on the server.
  • We're tracking file nodes on the client via manifest diffing rather than using linkrev shortcuts on the server.

I'm pretty confident that most of these issues are addressable.

But even if we can't get wire protocol version 2 on performance parity
with "getbundle," I still think it is important to have the set of low
level data-specific retrieval commands that we have implemented so
far. This is because the existence of such commands allows flexibility
in how clients access server data.

Diff Detail

Repository
rHG Mercurial
Lint
Automatic diff as part of commit; lint not applicable.
Unit
Automatic diff as part of commit; unit tests not applicable.

Event Timeline

indygreg created this revision.Sep 5 2018, 12:20 PM
durin42 accepted this revision.Sep 12 2018, 11:12 AM
This revision is now accepted and ready to land.Sep 12 2018, 11:12 AM
indygreg updated this revision to Diff 10970.Sep 12 2018, 1:11 PM
Closed by commit rHG039bf1eddc2e: exchangev2: fetch file revisions (authored by indygreg). · Explain WhySep 14 2018, 11:17 PM
This revision was automatically updated to reflect the committed changes.

Revision Contents
Changeset List

PathPackages
Mmercurial/exchangev2.py (102 lines)
Mtests/test-wireproto-exchangev2.t (120 lines)

Diff 11069

mercurial/exchangev2.py

# exchangev2.py - repository exchange for wire protocol version 2 # exchangev2.py - repository exchange for wire protocol version 2
# #
# Copyright 2018 Gregory Szorc <gregory.szorc@gmail.com> # Copyright 2018 Gregory Szorc <gregory.szorc@gmail.com>
# #
# This software may be used and distributed according to the terms of the # This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version. # GNU General Public License version 2 or any later version.
from __future__ import absolute_import from __future__ import absolute_import
import collections
import weakref import weakref
from .i18n import _ from .i18n import _
from .node import ( from .node import (
nullid, nullid,
short, short,
) )
from . import ( from . import (
phases.advanceboundary(repo, tr, phases.phasenames.index(phase), phases.advanceboundary(repo, tr, phases.phasenames.index(phase),
csetres['nodesbyphase'][phase]) csetres['nodesbyphase'][phase])
# Write bookmark updates. # Write bookmark updates.
bookmarks.updatefromremote(repo.ui, repo, csetres['bookmarks'], bookmarks.updatefromremote(repo.ui, repo, csetres['bookmarks'],
remote.url(), pullop.gettransaction, remote.url(), pullop.gettransaction,
explicit=pullop.explicitbookmarks) explicit=pullop.explicitbookmarks)
_fetchmanifests(repo, tr, remote, csetres['manifestnodes']) manres = _fetchmanifests(repo, tr, remote, csetres['manifestnodes'])
# Find all file nodes referenced by added manifests and fetch those
# revisions.
fnodes = _derivefilesfrommanifests(repo, manres['added'])
_fetchfiles(repo, tr, remote, fnodes, manres['linkrevs'])
def _pullchangesetdiscovery(repo, remote, heads, abortwhenunrelated=True): def _pullchangesetdiscovery(repo, remote, heads, abortwhenunrelated=True):
"""Determine which changesets need to be pulled.""" """Determine which changesets need to be pulled."""
if heads: if heads:
knownnode = repo.changelog.hasnode knownnode = repo.changelog.hasnode
if all(knownnode(head) for head in heads): if all(knownnode(head) for head in heads):
return heads, False, heads return heads, False, heads
iterrevisions(objs, progress), iterrevisions(objs, progress),
linkrevs.__getitem__, linkrevs.__getitem__,
weakref.proxy(tr))) weakref.proxy(tr)))
progress.complete() progress.complete()
return { return {
'added': added, 'added': added,
'linkrevs': linkrevs,
} }
def _derivefilesfrommanifests(repo, manifestnodes):
"""Determine what file nodes are relevant given a set of manifest nodes.
Returns a dict mapping file paths to dicts of file node to first manifest
node.
"""
ml = repo.manifestlog
fnodes = collections.defaultdict(dict)
for manifestnode in manifestnodes:
m = ml.get(b'', manifestnode)
# TODO this will pull in unwanted nodes because it takes the storage
# delta into consideration. What we really want is something that takes
# the delta between the manifest's parents. And ideally we would
# ignore file nodes that are known locally. For now, ignore both
# these limitations. This will result in incremental fetches requesting
# data we already have. So this is far from ideal.
md = m.readfast()
for path, fnode in md.items():
fnodes[path].setdefault(fnode, manifestnode)
return fnodes
def _fetchfiles(repo, tr, remote, fnodes, linkrevs):
def iterrevisions(objs, progress):
for filerevision in objs:
node = filerevision[b'node']
if b'deltasize' in filerevision:
basenode = filerevision[b'deltabasenode']
delta = next(objs)
elif b'revisionsize' in filerevision:
basenode = nullid
revision = next(objs)
delta = mdiff.trivialdiffheader(len(revision)) + revision
else:
continue
yield (
node,
filerevision[b'parents'][0],
filerevision[b'parents'][1],
node,
basenode,
delta,
# Flags not yet supported.
0,
)
progress.increment()
progress = repo.ui.makeprogress(
_('files'), unit=_('chunks'),
total=sum(len(v) for v in fnodes.itervalues()))
# TODO make batch size configurable
batchsize = 10000
fnodeslist = [x for x in sorted(fnodes.items())]
for i in pycompat.xrange(0, len(fnodeslist), batchsize):
batch = [x for x in fnodeslist[i:i + batchsize]]
if not batch:
continue
with remote.commandexecutor() as e:
fs = []
locallinkrevs = {}
for path, nodes in batch:
fs.append((path, e.callcommand(b'filedata', {
b'path': path,
b'nodes': sorted(nodes),
b'fields': {b'parents', b'revision'}
})))
locallinkrevs[path] = {
node: linkrevs[manifestnode]
for node, manifestnode in nodes.iteritems()}
for path, f in fs:
objs = f.result()
# Chomp off header objects.
next(objs)
store = repo.file(path)
store.addgroup(
iterrevisions(objs, progress),
locallinkrevs[path].__getitem__,
weakref.proxy(tr))

tests/test-wireproto-exchangev2.t

'\x04\\\x7f9\'\xda\x13\xe7Z\xf8\xf0\xe4\xf0HI\xe4a\xa9x\x0f', '\x04\\\x7f9\'\xda\x13\xe7Z\xf8\xf0\xe4\xf0HI\xe4a\xa9x\x0f',
'7\x9c\xb0\xc2\xe6d\\y\xdd\xc5\x9a\x1dG\'\xa9\xfb\x83\n\xeb&' '7\x9c\xb0\xc2\xe6d\\y\xdd\xc5\x9a\x1dG\'\xa9\xfb\x83\n\xeb&'
], ],
'tree': '' 'tree': ''
} }
received frame(size=11; request=1; stream=2; streamflags=stream-begin; type=command-response; flags=continuation) received frame(size=11; request=1; stream=2; streamflags=stream-begin; type=command-response; flags=continuation)
received frame(size=922; request=1; stream=2; streamflags=; type=command-response; flags=continuation) received frame(size=922; request=1; stream=2; streamflags=; type=command-response; flags=continuation)
received frame(size=0; request=1; stream=2; streamflags=; type=command-response; flags=eos) received frame(size=0; request=1; stream=2; streamflags=; type=command-response; flags=eos)
sending 2 commands
sending command filedata: {
'fields': set([
'parents',
'revision'
]),
'nodes': [
'+N\xb0s\x19\xbf\xa0w\xa4\n/\x04\x916Y\xae\xf0\xdaB\xda',
'\x9a8\x12)\x97\xb3\xac\x97\xbe*\x9a\xa2\xe5V\x83\x83A\xfd\xf2\xcc',
'\xc2\xa2\x05\xc8\xb2\xad\xe2J\xf2`b\xe5<\xd5\xbc8\x01\xd6`\xda'
],
'path': 'a'
}
sending command filedata: {
'fields': set([
'parents',
'revision'
]),
'nodes': [
'\x81\x9e%\x8d1\xa5\xe1`f)\xf3e\xbb\x90*\x1b!\xeeB\x16',
'\xb1zk\xd3g=\x9a\xb8\xce\xd5\x81\xa2\t\xf6/=\xa5\xccEx',
'\xc5\xb1\xf9\xd3n\x1c\xc18\xbf\xb6\xef\xb3\xde\xb7]\x8c\xcad\x94\xc3'
],
'path': 'b'
}
received frame(size=11; request=1; stream=2; streamflags=stream-begin; type=command-response; flags=continuation)
received frame(size=389; request=1; stream=2; streamflags=; type=command-response; flags=continuation)
received frame(size=0; request=1; stream=2; streamflags=; type=command-response; flags=eos)
received frame(size=11; request=3; stream=2; streamflags=; type=command-response; flags=continuation)
received frame(size=389; request=3; stream=2; streamflags=; type=command-response; flags=continuation)
received frame(size=0; request=3; stream=2; streamflags=; type=command-response; flags=eos)
updating the branch cache updating the branch cache
new changesets 3390ef850073:caa2a465451d (3 drafts) new changesets 3390ef850073:caa2a465451d (3 drafts)
All changesets should have been transferred All changesets should have been transferred
$ hg -R client-simple debugindex -c $ hg -R client-simple debugindex -c
rev linkrev nodeid p1 p2 rev linkrev nodeid p1 p2
0 0 3390ef850073 000000000000 000000000000 0 0 3390ef850073 000000000000 000000000000
'\x99/Gy\x02\x9a=\xf8\xd0fm\x00\xbb\x92OicN&A', '\x99/Gy\x02\x9a=\xf8\xd0fm\x00\xbb\x92OicN&A',
'\xa9\x88\xfbCX>\x87\x1d\x1e\xd5u\x0e\xe0t\xc6\xd8@\xbb\xbf\xc8' '\xa9\x88\xfbCX>\x87\x1d\x1e\xd5u\x0e\xe0t\xc6\xd8@\xbb\xbf\xc8'
], ],
'tree': '' 'tree': ''
} }
received frame(size=11; request=1; stream=2; streamflags=stream-begin; type=command-response; flags=continuation) received frame(size=11; request=1; stream=2; streamflags=stream-begin; type=command-response; flags=continuation)
received frame(size=376; request=1; stream=2; streamflags=; type=command-response; flags=continuation) received frame(size=376; request=1; stream=2; streamflags=; type=command-response; flags=continuation)
received frame(size=0; request=1; stream=2; streamflags=; type=command-response; flags=eos) received frame(size=0; request=1; stream=2; streamflags=; type=command-response; flags=eos)
sending 2 commands
sending command filedata: {
'fields': set([
'parents',
'revision'
]),
'nodes': [
'+N\xb0s\x19\xbf\xa0w\xa4\n/\x04\x916Y\xae\xf0\xdaB\xda',
'\x9a8\x12)\x97\xb3\xac\x97\xbe*\x9a\xa2\xe5V\x83\x83A\xfd\xf2\xcc'
],
'path': 'a'
}
sending command filedata: {
'fields': set([
'parents',
'revision'
]),
'nodes': [
'\x81\x9e%\x8d1\xa5\xe1`f)\xf3e\xbb\x90*\x1b!\xeeB\x16'
],
'path': 'b'
}
received frame(size=11; request=1; stream=2; streamflags=stream-begin; type=command-response; flags=continuation)
received frame(size=249; request=1; stream=2; streamflags=; type=command-response; flags=continuation)
received frame(size=0; request=1; stream=2; streamflags=; type=command-response; flags=eos)
received frame(size=11; request=3; stream=2; streamflags=; type=command-response; flags=continuation)
received frame(size=109; request=3; stream=2; streamflags=; type=command-response; flags=continuation)
received frame(size=0; request=3; stream=2; streamflags=; type=command-response; flags=eos)
updating the branch cache updating the branch cache
new changesets 3390ef850073:4432d83626e8 new changesets 3390ef850073:4432d83626e8
$ cd client-singlehead $ cd client-singlehead
$ hg log -G -T '{rev} {node} {phase}\n' $ hg log -G -T '{rev} {node} {phase}\n'
o 1 4432d83626e8a98655f062ec1f2a43b07f7fbbb0 public o 1 4432d83626e8a98655f062ec1f2a43b07f7fbbb0 public
| |
'\x04\\\x7f9\'\xda\x13\xe7Z\xf8\xf0\xe4\xf0HI\xe4a\xa9x\x0f', '\x04\\\x7f9\'\xda\x13\xe7Z\xf8\xf0\xe4\xf0HI\xe4a\xa9x\x0f',
'7\x9c\xb0\xc2\xe6d\\y\xdd\xc5\x9a\x1dG\'\xa9\xfb\x83\n\xeb&' '7\x9c\xb0\xc2\xe6d\\y\xdd\xc5\x9a\x1dG\'\xa9\xfb\x83\n\xeb&'
], ],
'tree': '' 'tree': ''
} }
received frame(size=11; request=1; stream=2; streamflags=stream-begin; type=command-response; flags=continuation) received frame(size=11; request=1; stream=2; streamflags=stream-begin; type=command-response; flags=continuation)
received frame(size=559; request=1; stream=2; streamflags=; type=command-response; flags=continuation) received frame(size=559; request=1; stream=2; streamflags=; type=command-response; flags=continuation)
received frame(size=0; request=1; stream=2; streamflags=; type=command-response; flags=eos) received frame(size=0; request=1; stream=2; streamflags=; type=command-response; flags=eos)
sending 2 commands
sending command filedata: {
'fields': set([
'parents',
'revision'
]),
'nodes': [
'+N\xb0s\x19\xbf\xa0w\xa4\n/\x04\x916Y\xae\xf0\xdaB\xda',
'\xc2\xa2\x05\xc8\xb2\xad\xe2J\xf2`b\xe5<\xd5\xbc8\x01\xd6`\xda'
],
'path': 'a'
}
sending command filedata: {
'fields': set([
'parents',
'revision'
]),
'nodes': [
'\x81\x9e%\x8d1\xa5\xe1`f)\xf3e\xbb\x90*\x1b!\xeeB\x16',
'\xb1zk\xd3g=\x9a\xb8\xce\xd5\x81\xa2\t\xf6/=\xa5\xccEx',
'\xc5\xb1\xf9\xd3n\x1c\xc18\xbf\xb6\xef\xb3\xde\xb7]\x8c\xcad\x94\xc3'
],
'path': 'b'
}
received frame(size=11; request=1; stream=2; streamflags=stream-begin; type=command-response; flags=continuation)
received frame(size=249; request=1; stream=2; streamflags=; type=command-response; flags=continuation)
received frame(size=0; request=1; stream=2; streamflags=; type=command-response; flags=eos)
received frame(size=11; request=3; stream=2; streamflags=; type=command-response; flags=continuation)
received frame(size=389; request=3; stream=2; streamflags=; type=command-response; flags=continuation)
received frame(size=0; request=3; stream=2; streamflags=; type=command-response; flags=eos)
updating the branch cache updating the branch cache
new changesets cd2534766bec:caa2a465451d (3 drafts) new changesets cd2534766bec:caa2a465451d (3 drafts)
(run 'hg update' to get a working copy) (run 'hg update' to get a working copy)
$ hg log -G -T '{rev} {node} {phase}\n' $ hg log -G -T '{rev} {node} {phase}\n'
o 4 caa2a465451dd1facda0f5b12312c355584188a1 draft o 4 caa2a465451dd1facda0f5b12312c355584188a1 draft
| |
o 3 e96ae20f4188487b9ae4ef3941c27c81143146e5 draft o 3 e96ae20f4188487b9ae4ef3941c27c81143146e5 draft
'\x04\\\x7f9\'\xda\x13\xe7Z\xf8\xf0\xe4\xf0HI\xe4a\xa9x\x0f', '\x04\\\x7f9\'\xda\x13\xe7Z\xf8\xf0\xe4\xf0HI\xe4a\xa9x\x0f',
'7\x9c\xb0\xc2\xe6d\\y\xdd\xc5\x9a\x1dG\'\xa9\xfb\x83\n\xeb&' '7\x9c\xb0\xc2\xe6d\\y\xdd\xc5\x9a\x1dG\'\xa9\xfb\x83\n\xeb&'
], ],
'tree': '' 'tree': ''
} }
received frame(size=11; request=1; stream=2; streamflags=stream-begin; type=command-response; flags=continuation) received frame(size=11; request=1; stream=2; streamflags=stream-begin; type=command-response; flags=continuation)
received frame(size=922; request=1; stream=2; streamflags=; type=command-response; flags=continuation) received frame(size=922; request=1; stream=2; streamflags=; type=command-response; flags=continuation)
received frame(size=0; request=1; stream=2; streamflags=; type=command-response; flags=eos) received frame(size=0; request=1; stream=2; streamflags=; type=command-response; flags=eos)
sending 2 commands
sending command filedata: {
'fields': set([
'parents',
'revision'
]),
'nodes': [
'+N\xb0s\x19\xbf\xa0w\xa4\n/\x04\x916Y\xae\xf0\xdaB\xda',
'\x9a8\x12)\x97\xb3\xac\x97\xbe*\x9a\xa2\xe5V\x83\x83A\xfd\xf2\xcc',
'\xc2\xa2\x05\xc8\xb2\xad\xe2J\xf2`b\xe5<\xd5\xbc8\x01\xd6`\xda'
],
'path': 'a'
}
sending command filedata: {
'fields': set([
'parents',
'revision'
]),
'nodes': [
'\x81\x9e%\x8d1\xa5\xe1`f)\xf3e\xbb\x90*\x1b!\xeeB\x16',
'\xb1zk\xd3g=\x9a\xb8\xce\xd5\x81\xa2\t\xf6/=\xa5\xccEx',
'\xc5\xb1\xf9\xd3n\x1c\xc18\xbf\xb6\xef\xb3\xde\xb7]\x8c\xcad\x94\xc3'
],
'path': 'b'
}
received frame(size=11; request=1; stream=2; streamflags=stream-begin; type=command-response; flags=continuation)
received frame(size=389; request=1; stream=2; streamflags=; type=command-response; flags=continuation)
received frame(size=0; request=1; stream=2; streamflags=; type=command-response; flags=eos)
received frame(size=11; request=3; stream=2; streamflags=; type=command-response; flags=continuation)
received frame(size=389; request=3; stream=2; streamflags=; type=command-response; flags=continuation)
received frame(size=0; request=3; stream=2; streamflags=; type=command-response; flags=eos)
updating the branch cache updating the branch cache
new changesets 3390ef850073:caa2a465451d (1 drafts) new changesets 3390ef850073:caa2a465451d (1 drafts)
$ hg -R client-bookmarks bookmarks $ hg -R client-bookmarks bookmarks
book-1 0:3390ef850073 book-1 0:3390ef850073
book-2 2:cd2534766bec book-2 2:cd2534766bec
Server-side bookmark moves are reflected during `hg pull` Server-side bookmark moves are reflected during `hg pull`