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Differential D4489

exchangev2: fetch manifest revisions
ClosedPublic

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

Details

Reviewers
durin42
Group Reviewers
hg-reviewers
Commits
rHGd292328e0143: exchangev2: fetch manifest revisions
Summary

Now that the server has support for retrieving manifest data, we can
implement the client bits to call it.

We teach the changeset fetching code to capture the manifest revisions
that are encountered on incoming changesets. We then feed this into a
new function which filters out known manifests and then batches up
manifest data requests to the server.

This is different from the previous wire protocol in a few notable
ways.

First, the client fetches manifest data separately and explicitly.
Before, we'd ask the server for data pertaining to some changesets
(via a "getbundle" command) and manifests (and files) would be sent
automatically. Providing an API for looking up just manifest data
separately gives clients much more flexibility for manifest management.
For example, a client may choose to only fetch manifest data on demand
instead of prefetching it (i.e. partial clone).

Second, we send N commands to the server for manifest retrieval instead
of 1. This property has a few nice side-effects. One is that the
deterministic nature of the requests lends itself to server-side
caching. For example, say the remote has 50,000 manifests. If the
server is configured to cache responses, each time a new commit
arrives, you will have a cache miss and need to regenerate all outgoing
data. But if you makes N requests requesting 10,000 manifests each,
a new commit will still yield cache hits on the initial, unchanged
manifest batches/requests.

A derived benefit from these properties is that resumable clone is
conceptually simpler to implement. When making a monolithic request
for all of the repository data, recovering from an interrupted clone
is hard because the server was in the driver's seat and was maintaining
state about all the data that needed transferred. With the client
driving fetching, the client can persist the set of unfetched entities
and retry/resume a fetch if something goes wrong. Or we can fetch all
data N changesets at a time and slowly build up a repository. This
approach is drastically easier to implement when we have server APIs
exposing low-level repository primitives (such as manifests and files).

We don't yet support tree manifests. But it should be possible to
implement that with the existing wire protocol command.

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, 11:14 AM
This revision is now accepted and ready to land.Sep 12 2018, 11:14 AM
indygreg updated this revision to Diff 10968.Sep 12 2018, 1:11 PM
Closed by commit rHGd292328e0143: exchangev2: fetch manifest revisions (authored by indygreg). · Explain WhySep 14 2018, 11:16 PM
This revision was automatically updated to reflect the committed changes.

Revision Contents
Changeset List

Diff 11067

mercurial/exchangev2.py

from .i18n import _ from .i18n import _
from .node import ( from .node import (
nullid, nullid,
short, short,
) )
from . import ( from . import (
bookmarks, bookmarks,
error,
mdiff, mdiff,
phases, phases,
pycompat, pycompat,
setdiscovery, setdiscovery,
) )
def pull(pullop): def pull(pullop):
"""Pull using wire protocol version 2.""" """Pull using wire protocol version 2."""
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'])
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
# The first emitted object is a header describing the data that # The first emitted object is a header describing the data that
# follows. # follows.
meta = next(objs) meta = next(objs)
progress = repo.ui.makeprogress(_('changesets'), progress = repo.ui.makeprogress(_('changesets'),
unit=_('chunks'), unit=_('chunks'),
total=meta.get(b'totalitems')) total=meta.get(b'totalitems'))
manifestnodes = {}
def linkrev(node): def linkrev(node):
repo.ui.debug('add changeset %s\n' % short(node)) repo.ui.debug('add changeset %s\n' % short(node))
# Linkrev for changelog is always self. # Linkrev for changelog is always self.
return len(cl) return len(cl)
def onchangeset(cl, node): def onchangeset(cl, node):
progress.increment() progress.increment()
revision = cl.changelogrevision(node)
# We need to preserve the mapping of changelog revision to node
# so we can set the linkrev accordingly when manifests are added.
manifestnodes[cl.rev(node)] = revision.manifest
nodesbyphase = {phase: set() for phase in phases.phasenames} nodesbyphase = {phase: set() for phase in phases.phasenames}
remotebookmarks = {} remotebookmarks = {}
# addgroup() expects a 7-tuple describing revisions. This normalizes # addgroup() expects a 7-tuple describing revisions. This normalizes
# the wire data to that format. # the wire data to that format.
# #
# This loop also aggregates non-revision metadata, such as phase # This loop also aggregates non-revision metadata, such as phase
# data. # data.
addrevisioncb=onchangeset) addrevisioncb=onchangeset)
progress.complete() progress.complete()
return { return {
'added': added, 'added': added,
'nodesbyphase': nodesbyphase, 'nodesbyphase': nodesbyphase,
'bookmarks': remotebookmarks, 'bookmarks': remotebookmarks,
'manifestnodes': manifestnodes,
}
def _fetchmanifests(repo, tr, remote, manifestnodes):
rootmanifest = repo.manifestlog.getstorage(b'')
# Some manifests can be shared between changesets. Filter out revisions
# we already know about.
fetchnodes = []
linkrevs = {}
seen = set()
for clrev, node in sorted(manifestnodes.iteritems()):
if node in seen:
continue
try:
rootmanifest.rev(node)
except error.LookupError:
fetchnodes.append(node)
linkrevs[node] = clrev
seen.add(node)
# TODO handle tree manifests
# addgroup() expects 7-tuple describing revisions. This normalizes
# the wire data to that format.
def iterrevisions(objs, progress):
for manifest in objs:
node = manifest[b'node']
if b'deltasize' in manifest:
basenode = manifest[b'deltabasenode']
delta = next(objs)
elif b'revisionsize' in manifest:
basenode = nullid
revision = next(objs)
delta = mdiff.trivialdiffheader(len(revision)) + revision
else:
continue
yield (
node,
manifest[b'parents'][0],
manifest[b'parents'][1],
# The value passed in is passed to the lookup function passed
# to addgroup(). We already have a map of manifest node to
# changelog revision number. So we just pass in the
# manifest node here and use linkrevs.__getitem__ as the
# resolution function.
node,
basenode,
delta,
# Flags not yet supported.
0
)
progress.increment()
progress = repo.ui.makeprogress(_('manifests'), unit=_('chunks'),
total=len(fetchnodes))
# Fetch manifests 10,000 per command.
# TODO have server advertise preferences?
# TODO make size configurable on client?
batchsize = 10000
# We send commands 1 at a time to the remote. This is not the most
# efficient because we incur a round trip at the end of each batch.
# However, the existing frame-based reactor keeps consuming server
# data in the background. And this results in response data buffering
# in memory. This can consume gigabytes of memory.
# TODO send multiple commands in a request once background buffering
# issues are resolved.
added = []
for i in pycompat.xrange(0, len(fetchnodes), batchsize):
batch = [node for node in fetchnodes[i:i + batchsize]]
if not batch:
continue
with remote.commandexecutor() as e:
objs = e.callcommand(b'manifestdata', {
b'tree': b'',
b'nodes': batch,
b'fields': {b'parents', b'revision'},
}).result()
# Chomp off header object.
next(objs)
added.extend(rootmanifest.addgroup(
iterrevisions(objs, progress),
linkrevs.__getitem__,
weakref.proxy(tr)))
progress.complete()
return {
'added': added,
} }

tests/test-wireproto-exchangev2.t

received frame(size=871; request=1; stream=2; streamflags=; type=command-response; flags=continuation) received frame(size=871; 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)
add changeset 3390ef850073 add changeset 3390ef850073
add changeset 4432d83626e8 add changeset 4432d83626e8
add changeset cd2534766bec add changeset cd2534766bec
add changeset e96ae20f4188 add changeset e96ae20f4188
add changeset caa2a465451d add changeset caa2a465451d
checking for updated bookmarks checking for updated bookmarks
sending 1 commands
sending command manifestdata: {
'fields': set([
'parents',
'revision'
]),
'nodes': [
'\x99/Gy\x02\x9a=\xf8\xd0fm\x00\xbb\x92OicN&A',
'\xa9\x88\xfbCX>\x87\x1d\x1e\xd5u\x0e\xe0t\xc6\xd8@\xbb\xbf\xc8',
'\xec\x80NH\x8c \x88\xc25\t\x9a\x10 u\x13\xbe\xcd\xc3\xdd\xa5',
'\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&'
],
'tree': ''
}
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=0; request=1; 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
| |
| o 2 cd2534766bece138c7c1afdc6825302f0f62d81f draft | o 2 cd2534766bece138c7c1afdc6825302f0f62d81f draft
| | | |
| o 1 4432d83626e8a98655f062ec1f2a43b07f7fbbb0 public | o 1 4432d83626e8a98655f062ec1f2a43b07f7fbbb0 public
|/ |/
o 0 3390ef850073fbc2f0dfff2244342c8e9229013a public o 0 3390ef850073fbc2f0dfff2244342c8e9229013a public
All manifests should have been transferred
$ hg -R client-simple debugindex -m
rev linkrev nodeid p1 p2
0 0 992f4779029a 000000000000 000000000000
1 1 a988fb43583e 992f4779029a 000000000000
2 2 ec804e488c20 a988fb43583e 000000000000
3 3 045c7f3927da 992f4779029a 000000000000
4 4 379cb0c2e664 045c7f3927da 000000000000
Cloning only a specific revision works Cloning only a specific revision works
$ hg --debug clone -U -r 4432d83626e8 http://localhost:$HGPORT client-singlehead $ hg --debug clone -U -r 4432d83626e8 http://localhost:$HGPORT client-singlehead
using http://localhost:$HGPORT/ using http://localhost:$HGPORT/
sending capabilities command sending capabilities command
sending 1 commands sending 1 commands
sending command lookup: { sending command lookup: {
'key': '4432d83626e8' 'key': '4432d83626e8'
] ]
} }
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=353; request=1; stream=2; streamflags=; type=command-response; flags=continuation) received frame(size=353; 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)
add changeset 3390ef850073 add changeset 3390ef850073
add changeset 4432d83626e8 add changeset 4432d83626e8
checking for updated bookmarks checking for updated bookmarks
sending 1 commands
sending command manifestdata: {
'fields': set([
'parents',
'revision'
]),
'nodes': [
'\x99/Gy\x02\x9a=\xf8\xd0fm\x00\xbb\x92OicN&A',
'\xa9\x88\xfbCX>\x87\x1d\x1e\xd5u\x0e\xe0t\xc6\xd8@\xbb\xbf\xc8'
],
'tree': ''
}
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=0; request=1; 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
| |
o 0 3390ef850073fbc2f0dfff2244342c8e9229013a public o 0 3390ef850073fbc2f0dfff2244342c8e9229013a public
$ hg debugindex -m
rev linkrev nodeid p1 p2
0 0 992f4779029a 000000000000 000000000000
1 1 a988fb43583e 992f4779029a 000000000000
Incremental pull works Incremental pull works
$ hg --debug pull $ hg --debug pull
pulling from http://localhost:$HGPORT/ pulling from http://localhost:$HGPORT/
using http://localhost:$HGPORT/ using http://localhost:$HGPORT/
sending capabilities command sending capabilities command
query 1; heads query 1; heads
sending 2 commands sending 2 commands
} }
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=571; request=1; stream=2; streamflags=; type=command-response; flags=continuation) received frame(size=571; 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)
add changeset cd2534766bec add changeset cd2534766bec
add changeset e96ae20f4188 add changeset e96ae20f4188
add changeset caa2a465451d add changeset caa2a465451d
checking for updated bookmarks checking for updated bookmarks
sending 1 commands
sending command manifestdata: {
'fields': set([
'parents',
'revision'
]),
'nodes': [
'\xec\x80NH\x8c \x88\xc25\t\x9a\x10 u\x13\xbe\xcd\xc3\xdd\xa5',
'\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&'
],
'tree': ''
}
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=0; request=1; 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
| |
| o 2 cd2534766bece138c7c1afdc6825302f0f62d81f draft | o 2 cd2534766bece138c7c1afdc6825302f0f62d81f draft
| | | |
| o 1 4432d83626e8a98655f062ec1f2a43b07f7fbbb0 public | o 1 4432d83626e8a98655f062ec1f2a43b07f7fbbb0 public
|/ |/
o 0 3390ef850073fbc2f0dfff2244342c8e9229013a public o 0 3390ef850073fbc2f0dfff2244342c8e9229013a public
$ hg debugindex -m
rev linkrev nodeid p1 p2
0 0 992f4779029a 000000000000 000000000000
1 1 a988fb43583e 992f4779029a 000000000000
2 2 ec804e488c20 a988fb43583e 000000000000
3 3 045c7f3927da 992f4779029a 000000000000
4 4 379cb0c2e664 045c7f3927da 000000000000
Phase-only update works Phase-only update works
$ hg -R ../server-simple phase --public -r caa2a465451dd $ hg -R ../server-simple phase --public -r caa2a465451dd
$ hg --debug pull $ hg --debug pull
pulling from http://localhost:$HGPORT/ pulling from http://localhost:$HGPORT/
using http://localhost:$HGPORT/ using http://localhost:$HGPORT/
sending capabilities command sending capabilities command
query 1; heads query 1; heads
add changeset 3390ef850073 add changeset 3390ef850073
add changeset 4432d83626e8 add changeset 4432d83626e8
add changeset cd2534766bec add changeset cd2534766bec
add changeset e96ae20f4188 add changeset e96ae20f4188
add changeset caa2a465451d add changeset caa2a465451d
checking for updated bookmarks checking for updated bookmarks
adding remote bookmark book-1 adding remote bookmark book-1
adding remote bookmark book-2 adding remote bookmark book-2
sending 1 commands
sending command manifestdata: {
'fields': set([
'parents',
'revision'
]),
'nodes': [
'\x99/Gy\x02\x9a=\xf8\xd0fm\x00\xbb\x92OicN&A',
'\xa9\x88\xfbCX>\x87\x1d\x1e\xd5u\x0e\xe0t\xc6\xd8@\xbb\xbf\xc8',
'\xec\x80NH\x8c \x88\xc25\t\x9a\x10 u\x13\xbe\xcd\xc3\xdd\xa5',
'\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&'
],
'tree': ''
}
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=0; request=1; 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`