# HG changeset patch
# User Durham Goode <durham@fb.com>
# Date 1435610664 25200
# Node ID d859123e0f47a398f4b7f0c7485de67e5ed34f31
# Parent  86fe3c404c1e70d9960679c260f9d0e42b86358b
convert: add config option for disabling ancestor parent checks

When converting merge commits, convert checks if any of the parents are
ancestors of any of the other parents. To do this, it builds an ancestor list
for every commit in the repository. On large repos this can take a long time
(30min+). Let's add an option for disabling this check to preserve performance.

The downside of this is that it may create unnecessary parent connections when
enabled (which is unfortunate, but not incorrect).

To verify, I ran the convert tests with the flag enabled, and verified the graph
changes were all just to add new parents that were ancestors of existing
parents.

diff -r 86fe3c404c1e -r d859123e0f47 hgext/convert/filemap.py
--- a/hgext/convert/filemap.py	Mon Jun 29 13:40:20 2015 -0700
+++ b/hgext/convert/filemap.py	Mon Jun 29 13:44:24 2015 -0700
@@ -156,6 +156,9 @@
         self.origparents = {}
         self.children = {}
         self.seenchildren = {}
+        # experimental config: convert.ignoreancestorcheck
+        self.ignoreancestorcheck = self.ui.configbool('convert',
+                                                      'ignoreancestorcheck')
 
     def before(self):
         self.base.before()
@@ -306,7 +309,7 @@
 
     def getchanges(self, rev, full):
         parents = self.commits[rev].parents
-        if len(parents) > 1:
+        if len(parents) > 1 and not self.ignoreancestorcheck:
             self.rebuild()
 
         # To decide whether we're interested in rev we:
@@ -332,9 +335,11 @@
             mp1 = self.parentmap[p1]
             if mp1 == SKIPREV or mp1 in knownparents:
                 continue
-            isancestor = any(p2 for p2 in parents
-                                  if p1 != p2 and mp1 != self.parentmap[p2]
-                                  and mp1 in self.wantedancestors[p2])
+
+            isancestor = (not self.ignoreancestorcheck and
+                          any(p2 for p2 in parents
+                              if p1 != p2 and mp1 != self.parentmap[p2]
+                                 and mp1 in self.wantedancestors[p2]))
             if not isancestor and not hasbranchparent and len(parents) > 1:
                 # This could be expensive, avoid unnecessary calls.
                 if self._cachedcommit(p1).branch == branch: