This is a subset of https://golang.org/cl/20022 with only the copyright
header lines, so the next CL will be smaller and more reviewable.
Go policy has been single space after periods in comments for some time.
The copyright header template at:
https://golang.org/doc/contribute.html#copyright
also uses a single space.
Make them all consistent.
Change-Id: Icc26c6b8495c3820da6b171ca96a74701b4a01b0
Reviewed-on: https://go-review.googlesource.com/20111
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Aeshash currently computes the hash of the empty string as
hash("", seed) = seed. This is bad because the hash of a compound
object with empty strings in it doesn't include information about
where those empty strings were. For instance [2]string{"", "foo"}
and [2]string{"foo", ""} might get the same hash.
Fix this by returning a scrambled seed instead of the seed itself.
With this fix, we can remove the scrambling done by the generated
array hash routines.
The test also rejects hash("", seed) = 0, if we ever thought
it would be a good idea to try that.
The fallback hash is already OK in this regard.
Change-Id: Iaedbaa5be8d6a246dc7e9383d795000e0f562037
Reviewed-on: https://go-review.googlesource.com/14129
Reviewed-by: jcd . <jcd@golang.org>
The hash tests generate occasional failures, quiet them some more.
In particular we can get 1 collision when the expected number is
.001 or so. That shouldn't be a dealbreaker.
Fixes#12311
Change-Id: I784e91b5d21f4f1f166dc51bde2d1cd3a7a3bfea
Reviewed-on: https://go-review.googlesource.com/13902
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
For arm and powerpc, as well as x86 without aes instructions.
Contains a mixture of ideas from cityhash and xxhash.
Compared to our old fallback on ARM, it's ~no slower on
small objects and up to ~50% faster on large objects. More
importantly, it is a much better hash function and thus has
less chance of bad behavior.
Fixes#8737
benchmark old ns/op new ns/op delta
BenchmarkHash5 173 181 +4.62%
BenchmarkHash16 252 212 -15.87%
BenchmarkHash64 575 419 -27.13%
BenchmarkHash1024 7173 3995 -44.31%
BenchmarkHash65536 516940 313173 -39.42%
BenchmarkHashStringSpeed 300 279 -7.00%
BenchmarkHashBytesSpeed 478 424 -11.30%
BenchmarkHashInt32Speed 217 207 -4.61%
BenchmarkHashInt64Speed 262 231 -11.83%
BenchmarkHashStringArraySpeed 609 631 +3.61%
Change-Id: I0a9335028f32b10ad484966e3019987973afd3eb
Reviewed-on: https://go-review.googlesource.com/1360
Reviewed-by: Russ Cox <rsc@golang.org>
