D4686: changegroup: reintroduce some comments that have gotten lost over the years

durin42 (Augie Fackler) phabricator at mercurial-scm.org
Thu Sep 20 19:39:38 UTC 2018


durin42 created this revision.
Herald added a subscriber: mercurial-devel.
Herald added a reviewer: hg-reviewers.

REVISION SUMMARY
  I got concerned about the correctness of the pruning logic, but I was
  misreading it. I didn't figure that out until I walked all the way
  back to https://phab.mercurial-scm.org/rHG0252abaafb8a54baab71e40cdee9761ecc25a670 from 20111, where I was finally able to see (in
  the deleted side of the change!) a complete explanation from
  https://phab.mercurial-scm.org/rHGb6d9ea0bc1070f75648ac9b729682a7066968fca in 2005.

REPOSITORY
  rHG Mercurial

REVISION DETAIL
  https://phab.mercurial-scm.org/D4686

AFFECTED FILES
  mercurial/changegroup.py

CHANGE DETAILS

diff --git a/mercurial/changegroup.py b/mercurial/changegroup.py
--- a/mercurial/changegroup.py
+++ b/mercurial/changegroup.py
@@ -1071,8 +1071,14 @@
             store = mfl.getstorage(tree)
 
             if not self._filematcher.visitdir(store.tree[:-1] or '.'):
+                # No nodes to send because this directory is out of
+                # the client's view of the repository (probably
+                # because of narrow clones).
                 prunednodes = []
             else:
+                # Avoid sending any manifest nodes we can prove the
+                # client already has by checking linkrevs. See the
+                # related comment in generatefiles().
                 prunednodes = self._prunemanifests(store, nodes, commonrevs)
             if tree and not prunednodes:
                 continue
@@ -1164,6 +1170,10 @@
                 return linkrevnodes[x]
 
             frev, flr = filerevlog.rev, filerevlog.linkrev
+            # Skip sending any filenode we know the client already
+            # has. This avoids over-sending files relatively
+            # inexpensively, so it's not a problem if we under-filter
+            # here.
             filenodes = [n for n in linkrevnodes
                          if flr(frev(n)) not in commonrevs]
 



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