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14 Commits

Author SHA1 Message Date
Uttam C Pawar
32add8d7c8 bytes: improve Compare function on amd64 for large byte arrays
This patch contains only loop unrolling change for size > 63B

Following are the performance numbers for various sizes on
On Haswell based system: Intel(R) Core(TM) i7-4770 CPU @ 3.40GHz.

benchcmp go.head.8.25.15.txt go.head.8.25.15.opt.txt
benchmark                       old ns/op     new ns/op     delta
BenchmarkBytesCompare1-4        5.37          5.37          +0.00%
BenchmarkBytesCompare2-4        5.37          5.38          +0.19%
BenchmarkBytesCompare4-4        5.37          5.37          +0.00%
BenchmarkBytesCompare8-4        4.42          4.38          -0.90%
BenchmarkBytesCompare16-4       4.27          4.45          +4.22%
BenchmarkBytesCompare32-4       5.30          5.36          +1.13%
BenchmarkBytesCompare64-4       6.93          6.78          -2.16%
BenchmarkBytesCompare128-4      10.3          9.50          -7.77%
BenchmarkBytesCompare256-4      17.1          13.8          -19.30%
BenchmarkBytesCompare512-4      31.3          22.1          -29.39%
BenchmarkBytesCompare1024-4     62.5          39.0          -37.60%
BenchmarkBytesCompare2048-4     112           73.2          -34.64%

Change-Id: I4eeb1c22732fd62cbac97ba757b0d29f648d4ef1
Reviewed-on: https://go-review.googlesource.com/11871
Reviewed-by: Keith Randall <khr@golang.org>
2015-08-26 03:52:20 +00:00
Alan Donovan
02dd98e9e7 Revert "bytes: document that Buffer values must not be copied"
This reverts commit b1177d390c.

Change-Id: Iffbd63d5993633143a81572b223e3c5dd2353206
Reviewed-on: https://go-review.googlesource.com/12581
Reviewed-by: Alan Donovan <adonovan@google.com>
2015-07-23 18:34:49 +00:00
Alan Donovan
b1177d390c bytes: document that Buffer values must not be copied
Change-Id: If0821a2af987b78ed8024b40d9ffa68032518b22
Reviewed-on: https://go-review.googlesource.com/12572
Reviewed-by: Robert Griesemer <gri@golang.org>
2015-07-23 16:59:20 +00:00
Dmitry Vyukov
0fb5475bdf bytes, strings: add LastIndexByte
Currently the packages have the following index functions:

func Index(s, sep []byte) int
func IndexAny(s []byte, chars string) int
func IndexByte(s []byte, c byte) int
func IndexFunc(s []byte, f func(r rune) bool) int
func IndexRune(s []byte, r rune) int

func LastIndex(s, sep []byte) int
func LastIndexAny(s []byte, chars string) int
func LastIndexFunc(s []byte, f func(r rune) bool) int

Searching for the last occurrence of a byte is quite common
for string parsing algorithms (e.g. find the last paren on a line).
Also addition of LastIndexByte makes the set more orthogonal.

Change-Id: Ida168849acacf8e78dd70c1354bef9eac5effafe
Reviewed-on: https://go-review.googlesource.com/9500
Reviewed-by: Rob Pike <r@golang.org>
2015-04-30 07:13:18 +00:00
Brad Fitzpatrick
c264c87335 bytes, strings: add Reader.Size methods
As noted on recently on golang-nuts, there's currently no way to know
the total size of a strings.Reader or bytes.Reader when using ReadAt
on them. Most callers resort to wrapping it in an io.SectionReader to
retain that information.

The SizeReaderAt abstraction (an io.ReaderAt with a Size() int64
method) has proven useful as a way of expressing a concurrency-safe
read-only number of bytes.

As one example, see http://talks.golang.org/2013/oscon-dl.slide#49 and
the rest of that presentation for its use in dl.google.com.

SizeReaderAt is also used in the open source google-api-go-client, and
within Google's internal codebase, where it exists in a public package
created in 2013 with the package comment: "These may migrate to the
standard library after we have enough experience with their feel."

I'm still as happy with the SizeReaderAt abstraction and its
composabilty as I was in 2013, so I'd like to make these two Readers
also be SizeReaderAts.

Fixes #9667

Change-Id: Ie6f145ada419dd116280472d8c029f046d5edf70
Reviewed-on: https://go-review.googlesource.com/3199
Reviewed-by: Andrew Gerrand <adg@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
Reviewed-by: Rob Pike <r@golang.org>
2015-04-06 08:53:47 +00:00
Josh Bleecher Snyder
5242d2cef4 bytes: fix comment
The the has been deleted.

Change-Id: I4290105435d4f1fd10c7014f913a3147ddeb3c2b
Reviewed-on: https://go-review.googlesource.com/8469
Reviewed-by: Ian Lance Taylor <iant@golang.org>
2015-04-04 02:00:51 +00:00
Cristian Staretu
90554be030 bytes: export Cap method for buffer
Obtaining the actual size of the underlying storage of the buffer can
be very useful in various scenarios. Long running programs which write
and read large amounts of data to buffers might have to recycle
buffers in order to avoid holding onto potentially huge buffers.

For example, a piece of code which buffers a lot of data in a buffer
might need to release the big buffer and start again with a smaller
buffer after it finished processing the huge amount of data.

In cases where pools of bytes.Buffer are used, being able to check the
size of the allocated data can be very useful.

Instead of forking bytes.Buffer or writing new code, we can export the
Cap() method.

Change-Id: I79d4f0a3cff53b9419d82c8122964761e9e38566
Reviewed-on: https://go-review.googlesource.com/8342
Reviewed-by: Rob Pike <r@golang.org>
2015-04-03 23:50:02 +00:00
Dave Cheney
e2543ef62c runtime: add runtime.cmpstring and bytes.Compare
Update #10007

Implement runtime.cmpstring and bytes.Compare in asm for arm.

benchmark                                old ns/op     new ns/op     delta
BenchmarkCompareBytesEqual               254           91.4          -64.02%
BenchmarkCompareBytesToNil               41.5          37.6          -9.40%
BenchmarkCompareBytesEmpty               40.7          37.6          -7.62%
BenchmarkCompareBytesIdentical           255           96.3          -62.24%
BenchmarkCompareBytesSameLength          125           60.9          -51.28%
BenchmarkCompareBytesDifferentLength     133           60.9          -54.21%
BenchmarkCompareBytesBigUnaligned        17985879      5669706       -68.48%
BenchmarkCompareBytesBig                 17097634      4926798       -71.18%
BenchmarkCompareBytesBigIdentical        16861941      4389206       -73.97%

benchmark                             old MB/s     new MB/s     speedup
BenchmarkCompareBytesBigUnaligned     58.30        184.95       3.17x
BenchmarkCompareBytesBig              61.33        212.83       3.47x
BenchmarkCompareBytesBigIdentical     62.19        238.90       3.84x

This is a collaboration between Josh Bleecher Snyder and myself.

Change-Id: Ib3944b8c410d0e12135c2ba9459bfe131df48edd
Reviewed-on: https://go-review.googlesource.com/8010
Reviewed-by: Keith Randall <khr@golang.org>
2015-03-25 22:46:39 +00:00
areski
3f12d27133 bytes, os/exec, strings: fix a few BUG comments
Regular expression noteMarker requires the definition of a (who) section
when reading note from a sequence of comments.

Change-Id: I9635de9b86f00d20ec108097fee4d4a8f76237b2
Reviewed-on: https://go-review.googlesource.com/1952
Reviewed-by: Russ Cox <rsc@golang.org>
2015-03-20 18:34:39 +00:00
Robert Griesemer
19c1b163e8 bytes, strings: improve documentation for Count functions
Fixes #9659.

Change-Id: If364d5984a0c9a48858ae524b1560f633e621826
Reviewed-on: https://go-review.googlesource.com/3181
Reviewed-by: Rob Pike <r@golang.org>
2015-01-22 18:28:35 +00:00
Brad Fitzpatrick
ee3a1ff6fd all: update old comments referencing *.goc files
Change-Id: Ibf05e55ffe3bb454809cd3450b790e44061511c7
Reviewed-on: https://go-review.googlesource.com/2890
Reviewed-by: Alan Donovan <adonovan@google.com>
2015-01-15 16:31:52 +00:00
Russ Cox
6077f0fc32 cmd/go: fix bytes and net the right way
Not sure why they used empty.s and all these other
packages were special cased in cmd/go instead.
Add them to the list.

This avoids problems with net .s files being compiled
with gcc in cgo mode and gcc not supporting // comments
on ARM.

Not a problem with bytes, but be consistent.

The last change fixed the ARM build but broke the Windows build.
Maybe *this* will make everyone happy. Sigh.

TBR=iant
CC=golang-codereviews
https://golang.org/cl/144530046
2014-09-24 19:18:01 -04:00
Russ Cox
e9ec8e7a26 bytes, strings: document that FieldsFunc f must not be stateful
Fixes #8738.

LGTM=adg
R=golang-codereviews, adg
CC=golang-codereviews
https://golang.org/cl/143260045
2014-09-18 19:40:31 -04:00
Russ Cox
c007ce824d build: move package sources from src/pkg to src
Preparation was in CL 134570043.
This CL contains only the effect of 'hg mv src/pkg/* src'.
For more about the move, see golang.org/s/go14nopkg.
2014-09-08 00:08:51 -04:00