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| author | Raymond Hettinger <python@rcn.com> | 2004-06-04 06:35:20 (GMT) |
|---|---|---|
| committer | Raymond Hettinger <python@rcn.com> | 2004-06-04 06:35:20 (GMT) |
| commit | 4ec44e851dafc78c534efad127403d167feb4180 (patch) | |
| tree | 2380e5f7da1889215340c97e3988fb2d94227276 /Objects/tupleobject.c | |
| parent | 4e49b836db96264b3b5236794a3200eea32b2519 (diff) | |
| download | cpython-4ec44e851dafc78c534efad127403d167feb4180.zip cpython-4ec44e851dafc78c534efad127403d167feb4180.tar.gz cpython-4ec44e851dafc78c534efad127403d167feb4180.tar.bz2 | |
Replaced arbitrary addend in tuple_hash with one that is known to generate
many more prime multipliers and that performs well on collision tests.
Diffstat (limited to 'Objects/tupleobject.c')
| -rw-r--r-- | Objects/tupleobject.c | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/Objects/tupleobject.c b/Objects/tupleobject.c index 4cb80f0..ff20b43 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; |