changeset 39640:039bf1eddc2e

exchangev2: fetch file revisions 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. Differential Revision: https://phab.mercurial-scm.org/D4491
author Gregory Szorc <gregory.szorc@gmail.com>
date Tue, 04 Sep 2018 10:42:24 -0700
parents 0e03e6a44dee
children aa7e312375cf
files mercurial/exchangev2.py tests/test-wireproto-exchangev2.t
diffstat 2 files changed, 221 insertions(+), 1 deletions(-) [+]
line wrap: on
line diff
--- a/mercurial/exchangev2.py	Wed Sep 05 09:10:17 2018 -0700
+++ b/mercurial/exchangev2.py	Tue Sep 04 10:42:24 2018 -0700
@@ -7,6 +7,7 @@
 
 from __future__ import absolute_import
 
+import collections
 import weakref
 
 from .i18n import _
@@ -58,7 +59,12 @@
                                remote.url(), pullop.gettransaction,
                                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):
     """Determine which changesets need to be pulled."""
@@ -291,4 +297,98 @@
 
     return {
         '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))
--- a/tests/test-wireproto-exchangev2.t	Wed Sep 05 09:10:17 2018 -0700
+++ b/tests/test-wireproto-exchangev2.t	Tue Sep 04 10:42:24 2018 -0700
@@ -94,6 +94,37 @@
   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)
+  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
   new changesets 3390ef850073:caa2a465451d (3 drafts)
 
@@ -189,6 +220,34 @@
   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)
+  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
   new changesets 3390ef850073:4432d83626e8
 
@@ -268,6 +327,36 @@
   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)
+  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
   new changesets cd2534766bec:caa2a465451d (3 drafts)
   (run 'hg update' to get a working copy)
@@ -421,6 +510,37 @@
   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)
+  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
   new changesets 3390ef850073:caa2a465451d (1 drafts)