D6941: revlog: add a way to control sidedata changes during revlog.clone

[marmoute (Pierre-Yves David)]

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

REVISION SUMMARY
  We introduce a new argument to pass a callable dealing with the side data logic.
  Since the side data are usually associated to higher level logic, the revlog
  code itself is unlikely to know that to do itself. As a result the higher level
  upgrade code will be responsible to decide what needs to changes. The lower
  level revlog.clone just get simple instructions to apply.

REPOSITORY
  rHG Mercurial

REVISION DETAIL
  https://phab.mercurial-scm.org/D6941

AFFECTED FILES
  mercurial/revlog.py

CHANGE DETAILS

diff --git a/mercurial/revlog.py b/mercurial/revlog.py
--- a/mercurial/revlog.py
+++ b/mercurial/revlog.py
@@ -2356,7 +2356,8 @@
     DELTAREUSEALL = {'always', 'samerevs', 'never', 'fulladd'}
 
     def clone(self, tr, destrevlog, addrevisioncb=None,
-            deltareuse=DELTAREUSESAMEREVS, forcedeltabothparents=None):
+              deltareuse=DELTAREUSESAMEREVS, forcedeltabothparents=None,
+              sidedatacompanion=None):
         """Copy this revlog to another, possibly with format changes.
 
         The destination revlog will contain the same revisions and nodes.
@@ -2397,6 +2398,20 @@
         In addition to the delta policy, the ``forcedeltabothparents``
         argument controls whether to force compute deltas against both parents
         for merges. By default, the current default is used.
+
+        If not None, the `sidedatacompanion` is callable that accept two
+        arguments:
+
+            (srcrevlog, rev)
+
+        and return a triplet that control changes to sidedata content from the
+        old revision to the new clone result:
+
+            (dropall, filterout, update)
+
+        * if `dropall` is True, all sidedata should be dropped
+        * `filterout` is a set of sidedata keys that should be dropped
+        * `update` is a mapping of additionnal/new key -> value
         """
         if deltareuse not in self.DELTAREUSEALL:
             raise ValueError(_('value for deltareuse invalid: %s') % deltareuse)
@@ -2429,7 +2444,7 @@
             destrevlog._deltabothparents = forcedeltabothparents or oldamd
 
             self._clone(tr, destrevlog, addrevisioncb, deltareuse,
-                        forcedeltabothparents)
+                        forcedeltabothparents, sidedatacompanion)
 
         finally:
             destrevlog._lazydelta = oldlazydelta
@@ -2437,7 +2452,7 @@
             destrevlog._deltabothparents = oldamd
 
     def _clone(self, tr, destrevlog, addrevisioncb, deltareuse,
-               forcedeltabothparents):
+               forcedeltabothparents, sidedatacompanion):
         """perform the core duty of `revlog.clone` after parameter processing"""
         deltacomputer = deltautil.deltacomputer(destrevlog)
         index = self.index
@@ -2452,16 +2467,30 @@
             p2 = index[entry[6]][7]
             node = entry[7]
 
+
+            sidedataactions = (False, [], {})
+            if sidedatacompanion is not None:
+                sidedataactions = sidedatacompanion(self, rev)
+
             # (Possibly) reuse the delta from the revlog if allowed and
             # the revlog chunk is a delta.
             cachedelta = None
             rawtext = None
-            if deltareuse == self.DELTAREUSEFULLADD:
-                text = self.revision(rev)
+            if any(sidedataactions) or deltareuse == self.DELTAREUSEFULLADD:
+                dropall, filterout, update = sidedataactions
+                text, sidedata = self._revisiondata(rev)
+                if dropall:
+                    sidedata = {}
+                for key in filterout:
+                    sidedata.pop(key, None)
+                sidedata.update(update)
+                if not sidedata:
+                    sidedata = None
                 destrevlog.addrevision(text, tr, linkrev, p1, p2,
                                        cachedelta=cachedelta,
                                        node=node, flags=flags,
-                                       deltacomputer=deltacomputer)
+                                       deltacomputer=deltacomputer,
+                                       sidedata=sidedata)
             else:
                 if destrevlog._lazydelta:
                     dp = self.deltaparent(rev)



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