[PATCH 1 of 5] revlog: return lazy set from findcommonmissing

Durham Goode durham at fb.com
Tue Nov 12 04:14:23 UTC 2013


# HG changeset patch
# User Durham Goode <durham at fb.com>
# Date 1384216802 28800
#      Mon Nov 11 16:40:02 2013 -0800
# Node ID 41801f3f1968e702e23d1f91bbe83e1f2b9ca133
# Parent  aa80446aacc3b1574211649cd8f190250b6b04b3
revlog: return lazy set from findcommonmissing

When computing the commonmissing, it greedily computes the entire set
immediately. On a large repo where the majority of history is irrelevant, this
causes a significant slow down.

Replacing it with a lazy set makes amend go from 11 seconds to 8.7 seconds.

diff --git a/mercurial/revlog.py b/mercurial/revlog.py
--- a/mercurial/revlog.py
+++ b/mercurial/revlog.py
@@ -401,7 +401,29 @@
         heads = [self.rev(n) for n in heads]
 
         # we want the ancestors, but inclusive
-        has = set(self.ancestors(common))
+        class lazyset(object):
+            def __init__(self, lazyset):
+                self.set = set()
+                self.lazyset = lazyset
+
+            def __contains__(self, value):
+                return value in self.set or value in self.lazyset
+
+            def __iter__(self):
+                set = self.set
+                for r in set:
+                    yield r
+                for r in self.lazyset:
+                    if not r in set:
+                        yield r
+
+            def add(self, value):
+                self.set.add(value)
+
+            def update(self, values):
+                self.set.update(values)
+
+        has = lazyset(self.ancestors(common))
         has.add(nullrev)
         has.update(common)
 



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