delta/go-git.git/src/sync, branch dev.go2go

all: go fmt std cmd (but revert vendor)

2021-02-20T03:54:50+00:00

Make all our package sources use Go 1.17 gofmt format
(adding //go:build lines).

Part of //go:build change (#41184).
See https://golang.org/design/draft-gobuild

Change-Id: Ia0534360e4957e58cd9a18429c39d0e32a6addb4
Reviewed-on: https://go-review.googlesource.com/c/go/+/294430
Trust: Russ Cox 
Run-TryBot: Russ Cox 
TryBot-Result: Go Bot 
Reviewed-by: Jason A. Donenfeld 
Reviewed-by: Ian Lance Taylor

sync: use 386 instead of x86-32 to refer to the 32 bit x86 architecture

2020-11-23T05:57:35+00:00

This aligns the naming with GOARCH using 386 as a build target for
this architecture and makes it more easily found when searching
for documentation related to the build target.

Change-Id: I393bb89dd2f71e568124107b13e1b288fbd0c76a
Reviewed-on: https://go-review.googlesource.com/c/go/+/271988
Trust: Martin Möhrmann 
Run-TryBot: Martin Möhrmann 
TryBot-Result: Go Bot 
Reviewed-by: Ian Lance Taylor

sync: document RWMutex race semantics

2020-11-18T20:12:03+00:00

RWMutex provides explicit acquire/release synchronization events to the
race detector to model the mutex. It disables sync events within the
methods to avoid e.g., the atomics from adding false synchronization
events, which could cause false negatives in the race detector.

Change-Id: I5126ce2efaab151811ac264864aab1fa025a4aaf
Reviewed-on: https://go-review.googlesource.com/c/go/+/270865
Run-TryBot: Michael Pratt 
TryBot-Result: Go Bot 
Reviewed-by: Austin Clements 
Trust: Michael Pratt

cmd/go,cmd/compile,sync: remove special import case in cmd/go

2020-10-26T20:12:53+00:00

CL 253748 introduced a special case in cmd/go to allow sync to import
runtime/internal/atomic. Besides introducing unnecessary complexity
into cmd/go, this breaks other packages (like gopls) that understand
how imports work, but don't understand this special case.

Fix this by using the more standard linkname-based approach to pull
the necessary functions from runtime/internal/atomic into sync. Since
these are compiler intrinsics, we also have to tell the compiler that
the linknamed symbols are intrinsics to get this optimization in sync.

Fixes #42196.

Change-Id: I1f91498c255c91583950886a89c3c9adc39a32f0
Reviewed-on: https://go-review.googlesource.com/c/go/+/265124
Trust: Austin Clements 
Run-TryBot: Austin Clements 
Reviewed-by: Bryan C. Mills 
Reviewed-by: Keith Randall 
Reviewed-by: Paul Murphy 
TryBot-Result: Go Bot

sync: document that Once must not be copied

2020-10-23T19:57:55+00:00

Fixes #42160.

Change-Id: I9bf8b6f0bf1eccd3ab32cbd94c812f768746d291
Reviewed-on: https://go-review.googlesource.com/c/go/+/264557
Trust: Dmitri Shuralyov 
Run-TryBot: Dmitri Shuralyov 
TryBot-Result: Go Bot 
Reviewed-by: Bryan C. Mills

cmd/compiler,cmd/go,sync: add internal {LoadAcq,StoreRel}64 on ppc64

2020-10-21T14:34:44+00:00

Add an internal atomic intrinsic for load with acquire semantics
(extending LoadAcq to 64b) and add LoadAcquintptr for internal
use within the sync package.  For other arches, this remaps to the
appropriate atomic.Load{,64} intrinsic which should not alter code
generation.

Similarly, add StoreRel{uintptr,64} for consistency, and inline.

Finally, add an exception to allow sync to directly use the
runtime/internal/atomic package which avoids more convoluted
workarounds (contributed by Lynn Boger).

In an extreme example, sync.(*Pool).pin consumes 20% of wall time
during fmt tests.  This is reduced to 5% on ppc64le/power9.

From the fmt benchmarks on ppc64le:

name                           old time/op  new time/op  delta
SprintfPadding                  468ns ± 0%   451ns ± 0%   -3.63%
SprintfEmpty                   73.3ns ± 0%  51.9ns ± 0%  -29.20%
SprintfString                   135ns ± 0%   122ns ± 0%   -9.63%
SprintfTruncateString           232ns ± 0%   214ns ± 0%   -7.76%
SprintfTruncateBytes            216ns ± 0%   202ns ± 0%   -6.48%
SprintfSlowParsingPath          162ns ± 0%   142ns ± 0%  -12.35%
SprintfQuoteString             1.00µs ± 0%  0.99µs ± 0%   -1.39%
SprintfInt                      117ns ± 0%   104ns ± 0%  -11.11%
SprintfIntInt                   190ns ± 0%   175ns ± 0%   -7.89%
SprintfPrefixedInt              232ns ± 0%   212ns ± 0%   -8.62%
SprintfFloat                    270ns ± 0%   255ns ± 0%   -5.56%
SprintfComplex                 1.01µs ± 0%  0.99µs ± 0%   -1.68%
SprintfBoolean                  127ns ± 0%   111ns ± 0%  -12.60%
SprintfHexString                220ns ± 0%   198ns ± 0%  -10.00%
SprintfHexBytes                 261ns ± 0%   252ns ± 0%   -3.45%
SprintfBytes                    600ns ± 0%   590ns ± 0%   -1.67%
SprintfStringer                 684ns ± 0%   658ns ± 0%   -3.80%
SprintfStructure               2.57µs ± 0%  2.57µs ± 0%   -0.12%
ManyArgs                        669ns ± 0%   646ns ± 0%   -3.44%
FprintInt                       140ns ± 0%   136ns ± 0%   -2.86%
FprintfBytes                    184ns ± 0%   181ns ± 0%   -1.63%
FprintIntNoAlloc                140ns ± 0%   136ns ± 0%   -2.86%
ScanInts                        929µs ± 0%   921µs ± 0%   -0.79%
ScanRecursiveInt                122ms ± 0%   121ms ± 0%   -0.11%
ScanRecursiveIntReaderWrapper   122ms ± 0%   122ms ± 0%   -0.18%

Change-Id: I4d66780261b57b06ef600229e475462e7313f0d6
Reviewed-on: https://go-review.googlesource.com/c/go/+/253748
Run-TryBot: Lynn Boger 
Reviewed-by: Lynn Boger 
Reviewed-by: Keith Randall 
Trust: Lynn Boger 
TryBot-Result: Go Bot

runtime/internal/atomic: panic nicely on unaligned 64-bit atomics

2020-10-16T17:31:17+00:00

On 386 and arm, unaligned 64-bit atomics aren't safe, so we check for
this and panic. Currently, we panic by dereferencing nil, which may be
expedient but is pretty user-hostile since it gives no hint of what
the actual problem was.

This CL replaces this with an actual panic. The only subtlety here is
now the atomic assembly implementations are calling back into Go, so
they have to play nicely with stack maps and stack scanning. On 386,
this just requires declaring NO_LOCAL_POINTERS. On arm, this is
somewhat more complicated: first, we have to move the alignment check
into the functions that have Go signatures. Then we have to support
both the tail call from these functions to the underlying
implementation (which requires that they have no frame) and the call
into Go to panic (which requires that they have a frame). We resolve
this by forcing them to have no frame and setting up the frame
manually just before the panic call.

Change-Id: I19f1e860045df64088013db37a18acea47342c69
Reviewed-on: https://go-review.googlesource.com/c/go/+/262778
Trust: Austin Clements 
Run-TryBot: Austin Clements 
TryBot-Result: Go Bot 
Reviewed-by: Cherry Zhang 
Reviewed-by: Michael Knyszek

sync: fix typo in pooldequeue

2020-10-14T13:38:41+00:00

.

Change-Id: I26fa26d67d01bcd583a1efaaf9a38398cbf793f7
GitHub-Last-Rev: ded020d02ca2e429f7c31065e5a27dae6eb7a611
GitHub-Pull-Request: golang/go#41932
Reviewed-on: https://go-review.googlesource.com/c/go/+/261477
Trust: Alberto Donizetti 
Reviewed-by: Austin Clements

sync: delete dirty keys inside Map.LoadAndDelete

2020-08-24T20:05:41+00:00

Fixes #40999

Change-Id: Ie32427e5cb5ed512b976b554850f50be156ce9f2
Reviewed-on: https://go-review.googlesource.com/c/go/+/250197
Run-TryBot: Emmanuel Odeke 
TryBot-Result: Gobot Gobot 
Reviewed-by: Bryan C. Mills

all: add empty line between copyright header and package clause

2020-08-17T09:45:44+00:00

Makes sure the copyright notice is not interpreted as the package level
godoc.

Change-Id: I2afce7c9d620f19d51ec1438b1d0db1774b57146
Reviewed-on: https://go-review.googlesource.com/c/go/+/248760
Run-TryBot: Tobias Klauser 
TryBot-Result: Gobot Gobot 
Reviewed-by: Dave Cheney