D5406: wireprotov2: unify file revision collection and linknode derivation

[indygreg (Gregory Szorc)]

indygreg created this revision.
Herald added subscribers: mercurial-devel, mjpieters.
Herald added a reviewer: hg-reviewers.

REVISION SUMMARY
  The old mechanism for choosing which file revisions to send in the
  haveparents=True case was buggy in multiple ways - the most severe
  of which being that file revisions were excluded when they shouldn't
  have been.
  
  This commit unifies the logic for deriving the filenodes that will
  be sent by the "filesdata" command. We now consistently read files
  data from manifests. The "haveparents" argument now controls whether
  we iterate ctx.files() or use the full manifest to derive relevant
  files.
  
  The logic here is still woefully lacking to fully support shallow
  clones. It will require an API break to fully address. This commit
  should at least make the server APIs emit proper data, which is
  strictly better than before.

REPOSITORY
  rHG Mercurial

REVISION DETAIL
  https://phab.mercurial-scm.org/D5406

AFFECTED FILES
  mercurial/help/internals/wireprotocolv2.txt
  mercurial/wireprotov2server.py
  tests/test-wireproto-command-filesdata.t
  tests/test-wireproto-exchangev2.t

CHANGE DETAILS

diff --git a/tests/test-wireproto-exchangev2.t b/tests/test-wireproto-exchangev2.t
--- a/tests/test-wireproto-exchangev2.t
+++ b/tests/test-wireproto-exchangev2.t
@@ -1300,21 +1300,6 @@
 
 #if reporevlogstore
   $ hg -R client-linknode-2 debugrevlogindex dupe-file
-  abort: revlog 'dupe-file' not found
-  [255]
+     rev linkrev nodeid       p1           p2
+       0       2 2ed2a3912a0b 000000000000 000000000000
 #endif
-
-  $ hg -R client-linknode-2 verify
-  checking changesets
-  checking manifests
-  crosschecking files in changesets and manifests
-  checking files
-   warning: revlog 'data/dupe-file.i' not in fncache!
-   2: empty or missing dupe-file
-   dupe-file at 2: manifest refers to unknown revision 2ed2a3912a0b
-  checked 3 changesets with 2 changes to 3 files
-  1 warnings encountered!
-  hint: run "hg debugrebuildfncache" to recover from corrupt fncache
-  2 integrity errors encountered!
-  (first damaged changeset appears to be 2)
-  [1]
diff --git a/tests/test-wireproto-command-filesdata.t b/tests/test-wireproto-command-filesdata.t
--- a/tests/test-wireproto-command-filesdata.t
+++ b/tests/test-wireproto-command-filesdata.t
@@ -1267,8 +1267,6 @@
     }
   ]
 
-TODO this is buggy
-
   $ sendhttpv2peer << EOF
   > command filesdata
   >     revisions eval:[{
@@ -1284,8 +1282,16 @@
   sending filesdata command
   response: gen[
     {
-      b'totalitems': 0,
-      b'totalpaths': 0
+      b'totalitems': 1,
+      b'totalpaths': 1
+    },
+    {
+      b'path': b'dupe-file',
+      b'totalitems': 1
+    },
+    {
+      b'linknode': b'G\xfc0X\t\x11#,\xb2dg[@(\x19\xde\xdd\xf6\xc6\xf0',
+      b'node': b'.\xd2\xa3\x91*\x0b$P C\xea\xe8N\xe4\xb2y\xc1\x8b\x90\xdd'
     }
   ]
 
diff --git a/mercurial/wireprotov2server.py b/mercurial/wireprotov2server.py
--- a/mercurial/wireprotov2server.py
+++ b/mercurial/wireprotov2server.py
@@ -1156,48 +1156,38 @@
     # changeset, it should probably be allowed to access files data for that
     # changeset.
 
-    cl = repo.changelog
-    clnode = cl.node
     outgoing = resolvenodes(repo, revisions)
     filematcher = makefilematcher(repo, pathfilter)
 
-    # Figure out what needs to be emitted.
-    changedpaths = set()
     # path -> {fnode: linknode}
     fnodes = collections.defaultdict(dict)
 
+    # We collect the set of relevant file revisions by iterating the changeset
+    # revisions and either walking the set of files recorded in the changeset
+    # or by walking the manifest at that revision. There is probably room for a
+    # storage-level API to request this data, as it can be expensive to compute
+    # and would benefit from caching or alternate storage from what revlogs
+    # provide.
     for node in outgoing:
         ctx = repo[node]
-        changedpaths.update(ctx.files())
-
-    changedpaths = sorted(p for p in changedpaths if filematcher(p))
+        mctx = ctx.manifestctx()
+        md = mctx.read()
 
-    # If ancestors are known, we send file revisions having a linkrev in the
-    # outgoing set of changeset revisions.
-    if haveparents:
-        outgoingclrevs = set(cl.rev(n) for n in outgoing)
-
-        for path in changedpaths:
-            try:
-                store = getfilestore(repo, proto, path)
-            except FileAccessError as e:
-                raise error.WireprotoCommandError(e.msg, e.args)
+        if haveparents:
+            checkpaths = ctx.files()
+        else:
+            checkpaths = md.keys()
 
-            for rev in store:
-                linkrev = store.linkrev(rev)
-
-                if linkrev in outgoingclrevs:
-                    fnodes[path].setdefault(store.node(rev), clnode(linkrev))
+        for path in checkpaths:
+            fnode = md[path]
 
-    # If ancestors aren't known, we walk the manifests and send all
-    # encountered file revisions.
-    else:
-        for node in outgoing:
-            mctx = repo[node].manifestctx()
+            if path in fnodes and fnode in fnodes[path]:
+                continue
 
-            for path, fnode in mctx.read().items():
-                if filematcher(path):
-                    fnodes[path].setdefault(fnode, node)
+            if not filematcher(path):
+                continue
+
+            fnodes[path].setdefault(fnode, node)
 
     yield {
         b'totalpaths': len(fnodes),
diff --git a/mercurial/help/internals/wireprotocolv2.txt b/mercurial/help/internals/wireprotocolv2.txt
--- a/mercurial/help/internals/wireprotocolv2.txt
+++ b/mercurial/help/internals/wireprotocolv2.txt
@@ -426,8 +426,10 @@
 has no file revisions data. This means that all referenced file revisions
 in the queried set of changeset revisions will be sent.
 
-TODO we'll probably want a more complicated mechanism for the client to
-specify which ancestor revisions are known.
+TODO we want a more complicated mechanism for the client to specify which
+ancestor revisions are known. This is needed so intelligent deltas can be
+emitted and so updated linknodes can be sent if the client needs to adjust
+its linknodes for existing file nodes to older changeset revisions.
 TODO we may want to make linknodes an array so multiple changesets can be
 marked as introducing a file revision, since this can occur with e.g. hidden
 changesets.



To: indygreg, #hg-reviewers
Cc: mjpieters, mercurial-devel