From 4ec44e851dafc78c534efad127403d167feb4180 Mon Sep 17 00:00:00 2001
From: Raymond Hettinger <python@rcn.com>
Date: Fri, 4 Jun 2004 06:35:20 +0000
Subject: [PATCH] Replaced arbitrary addend in tuple_hash with one that is
 known to generate many more prime multipliers and that performs well on
 collision tests.

---
 Objects/tupleobject.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/Objects/tupleobject.c b/Objects/tupleobject.c
index 4cb80f0ed50..ff20b43eeba 100644
--- a/Objects/tupleobject.c
+++ b/Objects/tupleobject.c
@@ -256,6 +256,14 @@ Done:
 	return result;
 }
 
+/* The addend 82520, was selected from the range(0, 1000000) for 
+   generating the greatest number of prime multipliers for tuples 
+   upto length eight:
+
+     1082527, 1165049, 1082531, 1165057, 1247581, 1330103, 1082533, 
+     1330111, 1412633, 1165069, 1247599, 1495177, 1577699
+*/
+
 static long
 tuplehash(PyTupleObject *v)
 {
@@ -270,7 +278,7 @@ tuplehash(PyTupleObject *v)
 		if (y == -1)
 			return -1;
 		x = (x ^ y) * mult;
-		mult += 69068L + len + len;
+		mult += 82520L + len + len;
 	}
 	if (x == -1)
 		x = -2;