revbranchcache: move out of branchmap onto localrepo

Previously the revbranchcache was a field inside the branchmap. This is bad for
a couple reasons:

1) There can be multiple branchmaps per repo (one for each filter level). There
can only be one revbranchcache per repo. In fact, a revbranchcache could only
exist on a branchmap that was for the unfiltered view, so you could have
branchmaps exist for which you couldn't have a revbranchcache. It was funky.
2) The write lifecycle for the revbranchcache is going to be different from
the branchmap (branchmap is greedily written early on, revbranchcache
should be lazily computed and written).

This patch moves the revbranchcache to live as a field on the localrepo
(alongside self._branchmap). This will allow us to handle it's lifecycle
differently, which will let us move it to be lazily computed in future patches.

mercurial/branchmap.py

@@ -96,6 +96,10 b' def updatecache(repo):'
     if revs:
         partial.update(repo, revs)
         partial.write(repo)
+
+    if repo._revbranchcache is not None:
+        repo._revbranchcache.write(repo)
+
     assert partial.validfor(repo), filtername
     repo._branchcaches[repo.filtername] = partial
 
@@ -134,7 +138,6 b' class branchcache(dict):'
             self._closednodes = set()
         else:
             self._closednodes = closednodes
-        self._revbranchcache = None
 
     def _hashfiltered(self, repo):
         """build hash of revision filtered in the current cache
@@ -226,9 +229,6 b' class branchcache(dict):'
             repo.ui.debug("couldn't write branch cache: %s\n" % inst)
             # Abort may be raise by read only opener
             pass
-        if self._revbranchcache:
-            self._revbranchcache.write(repo.unfiltered())
-            self._revbranchcache = None
 
     def update(self, repo, revgen):
         """Given a branchhead cache, self, that may have extra nodes or be
@@ -240,9 +240,8 b' class branchcache(dict):'
         # collect new branch entries
         newbranches = {}
         urepo = repo.unfiltered()
-        self._revbranchcache = revbranchcache(urepo)
-        getbranchinfo = self._revbranchcache.branchinfo
         ucl = urepo.changelog
+        getbranchinfo = repo.revbranchcache().branchinfo
         for r in revgen:
             branch, closesbranch = getbranchinfo(ucl, r)
             newbranches.setdefault(branch, []).append(r)

mercurial/localrepo.py

@@ -279,6 +279,7 b' class localrepository(object):'
 
 
         self._branchcaches = {}
+        self._revbranchcache = None
         self.filterpats = {}
         self._datafilters = {}
         self._transref = self._lockref = self._wlockref = None
@@ -726,6 +727,12 b' class localrepository(object):'
         branchmap.updatecache(self)
         return self._branchcaches[self.filtername]
 
+    @unfilteredmethod
+    def revbranchcache(self):
+        if not self._revbranchcache:
+            self._revbranchcache = branchmap.revbranchcache(self.unfiltered())
+        return self._revbranchcache
+
     def branchtip(self, branch, ignoremissing=False):
         '''return the tip node for a given branch
 

mercurial/statichttprepo.py

@@ -141,6 +141,7 b' class statichttprepository(localrepo.loc'
         self._tags = None
         self.nodetagscache = None
         self._branchcaches = {}
+        self._revbranchcache = None
         self.encodepats = None
         self.decodepats = None