treemanifest: make node reuse match flat manifest behavior
authorDurham Goode <durham@fb.com>
Wed, 01 Mar 2017 16:19:41 -0800
changeset 36218 c134a33b1d73896a616475127797ad7fcfa0608d
parent 36217 2cdb1239ff8c54e9c54878f06d9a5c5795fd517b
child 36219 7f869d81ab543f9cf442aabc545b92fe53b2c9d8
push id465
push usergszorc@mozilla.com
push dateSun, 12 Mar 2017 21:10:32 +0000
treemanifest: make node reuse match flat manifest behavior In a flat manifest, a node with the same content but different parents is still considered a new node. In the current tree manifests however, if the content is the same, we ignore the parents entirely and just reuse the existing node. In our external treemanifest extension, we want to allow having one treemanifest for every flat manifests, as a way of easeing the migration to treemanifests. To make this possible, let's change the root node treemanifest behavior to match the behavior for flat manifests, so we can have a 1:1 relationship. While this sounds like a BC breakage, it's not actually a state users can normally get in because: A) you can't make empty commits, and B) even if you try to make an empty commit (by making a commit then amending it's changes away), the higher level commit logic in localrepo.commitctx() forces the commit to use the original p1 manifest node if no files were changed. So this would only affect extensions and automation that reached passed the normal localrepo.commit() logic straight into the manifest logic.
mercurial/manifest.py
tests/test-treemanifest.t
--- a/mercurial/manifest.py
+++ b/mercurial/manifest.py
@@ -1245,31 +1245,35 @@ class manifestrevlog(revlog.revlog):
         if arraytext is not None:
             self.fulltextcache[n] = arraytext
 
         return n
 
     def _addtree(self, m, transaction, link, m1, m2, readtree):
         # If the manifest is unchanged compared to one parent,
         # don't write a new revision
-        if m.unmodifiedsince(m1) or m.unmodifiedsince(m2):
+        if self._dir != '' and (m.unmodifiedsince(m1) or m.unmodifiedsince(m2)):
             return m.node()
         def writesubtree(subm, subp1, subp2):
             sublog = self.dirlog(subm.dir())
             sublog.add(subm, transaction, link, subp1, subp2, None, None,
                        readtree=readtree)
         m.writesubtrees(m1, m2, writesubtree)
         text = m.dirtext(self._usemanifestv2)
-        # Double-check whether contents are unchanged to one parent
-        if text == m1.dirtext(self._usemanifestv2):
-            n = m1.node()
-        elif text == m2.dirtext(self._usemanifestv2):
-            n = m2.node()
-        else:
+        n = None
+        if self._dir != '':
+            # Double-check whether contents are unchanged to one parent
+            if text == m1.dirtext(self._usemanifestv2):
+                n = m1.node()
+            elif text == m2.dirtext(self._usemanifestv2):
+                n = m2.node()
+
+        if not n:
             n = self.addrevision(text, transaction, link, m1.node(), m2.node())
+
         # Save nodeid so parent manifest can calculate its nodeid
         m.setnode(n)
         return n
 
 class manifestlog(object):
     """A collection class representing the collection of manifest snapshots
     referenced by commits in the repository.
 
--- a/tests/test-treemanifest.t
+++ b/tests/test-treemanifest.t
@@ -852,8 +852,18 @@ other branch
   pulling from $TESTTMP/grafted-dir-repo (glob)
   searching for changes
   adding changesets
   adding manifests
   adding file changes
   added 1 changesets with 1 changes to 1 files (+1 heads)
   (run 'hg heads' to see heads, 'hg merge' to merge)
 
+Committing a empty commit does not duplicate root treemanifest
+  $ echo z >> z
+  $ hg commit -Aqm 'pre-empty commit'
+  $ hg rm z
+  $ hg commit --amend -m 'empty commit'
+  saved backup bundle to $TESTTMP/grafted-dir-repo-clone/.hg/strip-backup/cb99d5717cea-de37743b-amend-backup.hg (glob)
+  $ hg log -r 'tip + tip^' -T '{manifest}\n'
+  1:678d3574b88c
+  1:678d3574b88c
+  $ hg --config extensions.strip= strip -r . -q