tree cddf993a662d733e072270d4c58e570da089c714
parent 6635ad9975e2df3ac42b2a95a40b4803628ff68a
author lukechampine <luke.champine@gmail.com> 1528989540 +0000
committer Filippo Valsorda <filippo@golang.org> 1550879826 +0000

xts: reduce tweak allocations

The call to k2.Encrypt causes tweak to escape to the heap, resulting
in a 16-byte allocation for each call to Encrypt/Decrypt. Moving
tweak into the Cipher struct would allow it to be reused, but this
is ruled out by the Cipher docstring, which states that it is safe
for concurrent use. Instead, manage tweak arrays with a sync.Pool.
Benchmarks indicate that this amortizes allocation cost without
impacting performance.

benchmark          old ns/op     new ns/op     delta
BenchmarkXTS-4     234           245           +4.70%

benchmark          old allocs    new allocs    delta
BenchmarkXTS-4     2             0             -100.00%

benchmark          old bytes     new bytes     delta
BenchmarkXTS-4     32            0             -100.00%

Change-Id: I5e0dd8c2e1a1078a151bbeb1d0760936b6b56216
GitHub-Last-Rev: 14d81f589f3ada2b19511d592000657af3410a51
GitHub-Pull-Request: golang/crypto#51
Reviewed-on: https://go-review.googlesource.com/c/118535
Reviewed-by: Filippo Valsorda <filippo@golang.org>
Run-TryBot: Filippo Valsorda <filippo@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>