# HG changeset patch
# User Pierre-Yves David <pierre-yves.david@ens-lyon.org>
# Date 1489263682 28800
# Node ID 62219171986348b606079dbd65a3ffea0d4083d1
# Parent  338d5600376c89aa7bc5eb4a1ebccd3a5e7cba47
stablerange: adds some caching of the subranges

The goal of subranges is to be as reusable as possible, so we cache the subrange
relationship to take advantage of this.

diff --git a/hgext3rd/evolve/obsdiscovery.py b/hgext3rd/evolve/obsdiscovery.py
--- a/hgext3rd/evolve/obsdiscovery.py
+++ b/hgext3rd/evolve/obsdiscovery.py
@@ -579,6 +579,11 @@
         return result
 
     def subranges(self):
+        if not util.safehasattr(self._repo, '_subrangecache'):
+            self._repo._subrangecache = {}
+        cached = self._repo._subrangecache.get(self)
+        if cached is not None:
+            return cached
         if len(self) == 1:
             return []
         step = _hlp2(self.depth)
@@ -589,10 +594,13 @@
             step //= 2
         if self.index == standard_start:
             slicesize = _hlp2(len(self))
-            return self._slicesat(self.index + slicesize)
+            slicepoint = self.index + slicesize
         else:
             assert standard_start < self.depth
-            return self._slicesat(standard_start)
+            slicepoint = standard_start
+        result = self._slicesat(slicepoint)
+        self._repo._subrangecache[self] = result
+        return result
 
     @util.propertycache
     def obshash(self):