repo: implement headrevs and heads

Summary:
In a future change we want `heads()` to include working parents and bookmarks
unconditionally. That version of `heads()` needs to be used everywhere,
including legacy exchange logic using branchmap.

Since `changelog` does not have access to working copy parents or bookmarks,
let's implement the `heads` and `headrevs` APIs on the `repo` object instead.

The next diff will migrate users of `changelog.headrevs` to `repo.headrevs`.

Reviewed By: markbt

Differential Revision: D18366734

fbshipit-source-id: 8791aaa57efeb1c6d19d6a4502376aeb26832772

edenscm/mercurial/changelog.py

@@ -375,11 +375,15 @@ class changelog(revlog.revlog):
     def reachableroots(self, minroot, heads, roots, includepath=False):
         return self.index.reachableroots2(minroot, heads, roots, includepath)
 
-    def headrevs(self, includepublic=True, includedraft=True):
+    def headrevs(self):
+        return self._headrevs([])
+
+    def _headrevs(self, additionalheads, includepublic=True, includedraft=True):
+        # This should only be used by repo.heads()
         if self._uiconfig.configbool("experimental", "narrow-heads"):
             publicnodes, draftnodes = self._remotenodes()
             torev = self.nodemap.__getitem__
-            nodes = []
+            nodes = list(additionalheads)
             if includepublic:
                 nodes += publicnodes
             if includedraft:

edenscm/mercurial/localrepo.py

@@ -242,8 +242,8 @@ class localpeer(repository.peer):
         else:
             return changegroup.getunbundler("01", cb, None)
 
-    def heads(self):
-        return self._repo.heads()
+    def heads(self, *args, **kwargs):
+        return self._repo.heads(*args, **kwargs)
 
     def known(self, nodes):
         return self._repo.known(nodes)
@@ -2558,15 +2558,24 @@ class localrepository(object):
         """Used by workingctx to clear post-dirstate-status hooks."""
         del self._postdsstatus[:]
 
-    def heads(self, start=None):
-        if start is None:
-            cl = self.changelog
-            headrevs = reversed(cl.headrevs())
-            return [cl.node(rev) for rev in headrevs]
+    def headrevs(self, start=None, includepublic=True, includedraft=True, reverse=True):
+        if includedraft:
+            nodes = list(self.nodes("parents() + bookmark()"))
+        else:
+            nodes = []
+        cl = self.changelog
+        headrevs = cl._headrevs(nodes, includepublic, includedraft)
+        if start is not None:
+            startrev = cl.rev(start)
+            headrevs = [r for r in headrevs if r > startrev]
+        if reverse:
+            return list(reversed(headrevs))
+        else:
+            return headrevs
 
-        heads = self.changelog.heads(start)
-        # sort the output in rev descending order
-        return sorted(heads, key=self.changelog.rev, reverse=True)
+    def heads(self, start=None, includepublic=True, includedraft=True):
+        headrevs = self.headrevs(start, includepublic, includedraft)
+        return map(self.changelog.node, headrevs)
 
     def branchheads(self, branch=None, start=None, closed=False):
         """return a (possibly filtered) list of heads for the given branch

edenscm/mercurial/phases.py

@@ -321,12 +321,8 @@ class phasecache(object):
                 def torevs(nodes):
                     return list(repo.revs("%ln", nodes))
 
-                publicheadrevs = cl.headrevs(includepublic=True, includedraft=False)
-                draftheadrevs = cl.headrevs(includepublic=False, includedraft=True)
-
-                # Also consider "." and bookmarks as drafts.
-                # This prevents them (and their ancestors) from being hidden (secret).
-                draftheadrevs += list(repo.revs("parents() + bookmark()"))
+                publicheadrevs = repo.headrevs(includepublic=True, includedraft=False)
+                draftheadrevs = repo.headrevs(includepublic=False, includedraft=True)
 
                 self._publicrevs, self._draftrevs = cl.index2.phasesets(
                     publicheadrevs, draftheadrevs