delta/go-git.git/src/compress, branch dev.typealias

all: test adjustments for the iOS builder

2017-01-14T03:27:53+00:00

The working directory is now adjusted to match the typical Go test
working directory in main, as the old trick for adjusting earlier
stopped working with the latest version of LLDB bugs.

That means the small number of places where testdata files are
read before main is called no longer work. This CL adjusts those
reads to happen after main is called. (This has the bonus effect of
not reading some benchmark testdata files in all.bash.)

Fixes compress/bzip2, go/doc, go/parser, os, and time package
tests on the iOS builder.

Change-Id: If60f026aa7848b37511c36ac5e3985469ec25209
Reviewed-on: https://go-review.googlesource.com/35255
Run-TryBot: David Crawshaw 
Reviewed-by: Brad Fitzpatrick 
TryBot-Result: Gobot Gobot

compress/flate: avoid large stack growth in fillDeflate

2017-01-12T19:15:57+00:00

Ranging over an array causes the array to be copied over to the
stack, which cause large re-growths. Instead, we should iterate
over slices of the array.

Also, assigning a large struct literal uses the stack even
though the actual fields being populated are small in comparison
to the entirety of the struct (see #18636).

Fixing the stack growth does not alter CPU-time performance much
since the stack-growth and copying was such a tiny portion of the
compression work:

name                         old time/op    new time/op    delta
Encode/Digits/Default/1e4-8     332µs ± 1%     332µs ± 1%   ~     (p=0.796 n=10+10)
Encode/Digits/Default/1e5-8    5.07ms ± 2%    5.05ms ± 1%   ~       (p=0.815 n=9+8)
Encode/Digits/Default/1e6-8    53.7ms ± 1%    53.9ms ± 1%   ~     (p=0.075 n=10+10)
Encode/Twain/Default/1e4-8      380µs ± 1%     380µs ± 1%   ~     (p=0.684 n=10+10)
Encode/Twain/Default/1e5-8     5.79ms ± 2%    5.79ms ± 1%   ~      (p=0.497 n=9+10)
Encode/Twain/Default/1e6-8     61.5ms ± 1%    61.8ms ± 1%   ~     (p=0.247 n=10+10)

name                         old speed      new speed      delta
Encode/Digits/Default/1e4-8  30.1MB/s ± 1%  30.1MB/s ± 1%   ~     (p=0.753 n=10+10)
Encode/Digits/Default/1e5-8  19.7MB/s ± 2%  19.8MB/s ± 1%   ~       (p=0.795 n=9+8)
Encode/Digits/Default/1e6-8  18.6MB/s ± 1%  18.5MB/s ± 1%   ~     (p=0.072 n=10+10)
Encode/Twain/Default/1e4-8   26.3MB/s ± 1%  26.3MB/s ± 1%   ~     (p=0.616 n=10+10)
Encode/Twain/Default/1e5-8   17.3MB/s ± 2%  17.3MB/s ± 1%   ~      (p=0.484 n=9+10)
Encode/Twain/Default/1e6-8   16.3MB/s ± 1%  16.2MB/s ± 1%   ~     (p=0.238 n=10+10)

Updates #18636
Fixes #18625

Change-Id: I471b20339bf675f63dc56d38b3acdd824fe23328
Reviewed-on: https://go-review.googlesource.com/35122
Reviewed-by: Brad Fitzpatrick 
Run-TryBot: Joe Tsai 
TryBot-Result: Gobot Gobot

compress/gzip: skip TestGZIPFilesHaveZeroMTimes on non-builders

2017-01-11T17:48:09+00:00

Fixes #18604

Change-Id: I89221d5e632042167dfced068e1dc14e932cd618
Reviewed-on: https://go-review.googlesource.com/35111
Run-TryBot: Joe Tsai 
TryBot-Result: Gobot Gobot 
Reviewed-by: Brad Fitzpatrick

compress/flate: add examples

2016-11-12T18:42:35+00:00

Updates #16360

Change-Id: I66ff23e0501363f58fe891d5e95806422071f93b
Reviewed-on: https://go-review.googlesource.com/30162
Run-TryBot: Brad Fitzpatrick 
TryBot-Result: Gobot Gobot 
Reviewed-by: Brad Fitzpatrick

all: sprinkle t.Parallel on some slow tests

2016-11-04T16:56:57+00:00

I used the slowtests.go tool as described in
https://golang.org/cl/32684 on packages that stood out.

go test -short std drops from ~56 to ~52 seconds.

This isn't a huge win, but it was mostly an exercise.

Updates #17751

Change-Id: I9f3402e36a038d71e662d06ce2c1d52f6c4b674d
Reviewed-on: https://go-review.googlesource.com/32751
Run-TryBot: Brad Fitzpatrick 
TryBot-Result: Gobot Gobot 
Reviewed-by: Ian Lance Taylor

compress/flate: tighten the BestSpeed max match offset bound.

2016-10-30T22:52:14+00:00

Previously, we were off by one.

Also fix a comment typo.

Change-Id: Ib94d23acc56d5fccd44144f71655481f98803ac8
Reviewed-on: https://go-review.googlesource.com/32149
Reviewed-by: Joe Tsai 
Run-TryBot: Joe Tsai 
TryBot-Result: Gobot Gobot

compress/gzip: only encode MTIME if it is valid

2016-10-29T23:29:13+00:00

The GZIP format records the ModTime as an uint32 counting seconds since
the Unix epoch. The zero value is explicitly defined in section 2.3.1
as meaning no timestamp is available.

Currently, the Writer always encodes the ModTime even if it is the zero
time.Time value, which causes the Writer to try and encode the value
-62135596800 into the uint32 MTIME field. This causes an overflow and
results in our GZIP files having MTIME fields indicating a date in 2042-07-13.

We alter the Writer to only encode ModTime if the value does not underflow
the MTIME field (i.e., it is newer than the Unix epoch). We do not attempt
to fix what happens when the timestamp overflows in the year 2106.

We alter the Reader to only decode ModTime if the value is non-zero.
There is no risk of overflowing time.Time when decoding.

Fixes #17663

Change-Id: Ie1b65770c6342cd7b14aeebe10e5a49e6c9eb730
Reviewed-on: https://go-review.googlesource.com/32325
Reviewed-by: Brad Fitzpatrick 
Run-TryBot: Brad Fitzpatrick 
TryBot-Result: Gobot Gobot

compress/flate: make compression level 0 consistent

2016-10-27T00:58:30+00:00

Tests for determinism was not working as intended since io.Copybuffer
uses the io.WriterTo if available.

This exposed that level 0 (no compression) changed output
based on the number of writes and buffers given to the
writer.

Previously, Write would emit a new raw block (BTYPE=00) for
every non-empty call to Write.

This CL fixes it such that a raw block is only emitted upon
the following conditions:
 	* A full window is obtained (every 65535 bytes)
 	* Flush is called
 	* Close is called

Change-Id: I807f866d97e2db7820f11febab30a96266a6cbf1
Reviewed-on: https://go-review.googlesource.com/31174
Run-TryBot: Joe Tsai 
TryBot-Result: Gobot Gobot 
Reviewed-by: Joe Tsai

compress/flate: level 1 (best speed) match across blocks

2016-10-27T00:50:06+00:00

This change makes deflate level 1 (best speed) match across
block boundaries. This comes at a small speed penalty,
but improves compression on almost all output.

Sample numbers on various content types:

enwik9:            391052014 ->  382578469 bytes, 77.59 -> 74.28 MB/s
adresser.001:       57269799 ->   47756095 bytes, 287.84 -> 357.86 MB/s
10gb:             5233055166 -> 5198328382 bytes, 105.85 -> 96.99 MB/s
rawstudio-mint14: 3972329211 -> 3927423364 bytes, 100.07 -> 94.22 MB/s
sites:             165556800 ->  163178702 bytes, 72.31 -> 70.15 MB/s
objectfiles:       115962472 ->  111649524 bytes, 132.60 -> 128.05 MB/s
sharnd.out:        200015283 ->  200015283 bytes, 221.50 -> 218.83 MB/s

Change-Id: I62a139e5c06976e803439a4268acede5139b8cfc
Reviewed-on: https://go-review.googlesource.com/31640
Reviewed-by: Joe Tsai 
Reviewed-by: Nigel Tao

all: minor vet fixes

2016-10-24T17:27:37+00:00

Change-Id: I22f0f3e792052762499f632571155768b4052bc9
Reviewed-on: https://go-review.googlesource.com/31759
Run-TryBot: Josh Bleecher Snyder 
TryBot-Result: Gobot Gobot 
Reviewed-by: Brad Fitzpatrick