[PATCH 3 of 5 V2] revlog: add a callback for when revisions are added

[Gregory Szorc]

# HG changeset patch
# User Gregory Szorc <gregory.szorc at gmail.com>
# Date 1436997222 25200
#      Wed Jul 15 14:53:42 2015 -0700
# Node ID 3c13ae7f08b610bb5ff0e7aba3a3e35d0369983c
# Parent  8510f2a1d3b2ec3231391dc0cf9a865b696a22cb
revlog: add a callback for when revisions are added

A subsequent patch will add a feature that performs iterative
computation as changesets are added from a changegroup. To facilitate
this type of processing in a generic manner, we add a mechanism for
calling a function whenever a revision is added from a changegroup.

diff --git a/mercurial/revlog.py b/mercurial/revlog.py
--- a/mercurial/revlog.py
+++ b/mercurial/revlog.py
@@ -1235,9 +1235,10 @@ class revlog(object):
             return ('u', text)
         return ("", bin)
 
     def _addrevision(self, node, text, transaction, link, p1, p2, flags,
-                     cachedelta, ifh, dfh, returntext=False):
+                     cachedelta, ifh, dfh, returntext=False,
+                     addrevisioncb=None):
         """internal function to add revisions to the log
 
         see addrevision for argument descriptions.
         invariants:
@@ -1364,8 +1365,11 @@ class revlog(object):
         if type(text) == str: # only accept immutable objects
             self._cache = (node, curr, text)
         self._basecache = (curr, chainbase)
 
+        if addrevisioncb:
+            addrevisioncb(self, node)
+
         if returntext:
             return node, buildtext()
         else:
             return node
@@ -1387,15 +1391,19 @@ class revlog(object):
             ifh.write(data[0])
             ifh.write(data[1])
             self.checkinlinesize(transaction, ifh)
 
-    def addgroup(self, bundle, linkmapper, transaction):
+    def addgroup(self, bundle, linkmapper, transaction, addrevisioncb=None):
         """
         add a delta group
 
         given a set of deltas, add them to the revision log. the
         first delta is against its parent, which should be in our
         log, the rest are against the previous delta.
+
+        If ``addrevisioncb`` is specified, it will be called with arguments of
+        this revlog instance and the node that was added. Derived classes may
+        change the arguments.
         """
 
         # track the base of the current delta log
         content = []
@@ -1466,9 +1474,10 @@ class revlog(object):
                     flags |= REVIDX_ISCENSORED
 
                 chain = self._addrevision(node, None, transaction, link,
                                           p1, p2, flags, (baserev, delta),
-                                          ifh, dfh)
+                                          ifh, dfh,
+                                          addrevisioncb=addrevisioncb)
                 if not dfh and not self._inline:
                     # addrevision switched from inline to conventional
                     # reopen the index
                     ifh.close()