# HG changeset patch
# User Jun Wu <quark@fb.com>
# Date 1463254437 -3600
# Node ID 372afb75f465ef3c9d124cd435d0715a17f835cc
# Parent  0094f222c5dc9eb17ddd290c931c08d4e9f7d91d
maps: add the "branchmaxrevnum" method to RevMap

Iterating the RevMap can be very expensive for large repos. To prevent future
code from iterating the possibly huge RevMap causing performance issues, it's
a good idea to clean all iterating code outside RevMap.

This patch adds a method used by "get_parent_svn_branch_and_rev".

In the future, we will have a SqliteRevMap, which will have an efficient
implementation for this query, and it will disable "__iter__" to prevent
future performance issues.

diff --git a/hgsubversion/maps.py b/hgsubversion/maps.py
--- a/hgsubversion/maps.py
+++ b/hgsubversion/maps.py
@@ -355,6 +355,13 @@ class RevMap(dict):
         check = lambda x: x[0][1] == branch and x[0][0] < rev.revnum
         return sorted(filter(check, self.iteritems()), reverse=True)
 
+    def branchmaxrevnum(self, branch, maxrevnum):
+        result = 0
+        for num, br in self.iterkeys():
+            if br == branch and num <= maxrevnum and num > result:
+                result = num
+        return result
+
     @property
     def lasthash(self):
         lines = list(self._readmapfile())