errgroup: remove duplicated comment

Change-Id: I5cdcc5034ccd87b939a406693e97485553ab60fa
Reviewed-on: https://go-review.googlesource.com/c/sync/+/676715
Reviewed-by: Dmitri Shuralyov <[email protected]>
Reviewed-by: Alan Donovan <[email protected]>
Auto-Submit: Alan Donovan <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>

errgroup: propagate panic and Goexit through Wait

Recovered panic values are wrapped and saved in Group.
Goexits are detected by a sentinel value set after the given function
returns normally. Wait propagates the first instance of a panic or
Goexit.

According to the runtime.Goexit after the code will not be executed,
with a bool, if f not call runtime.Goexit, is true,
determine whether to propagate runtime.Goexit.

Fixes golang/go#53757

Change-Id: Ic6426fc014fd1c4368ebaceef5b0d6163770a099
Reviewed-on: https://go-review.googlesource.com/c/sync/+/644575
Reviewed-by: Sean Liao <[email protected]>
Auto-Submit: Alan Donovan <[email protected]>
Commit-Queue: Alan Donovan <[email protected]>
Reviewed-by: Alan Donovan <[email protected]>
Reviewed-by: Dmitri Shuralyov <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>

errgroup: document calling Go before Wait

Fixes golang/go#70284

Change-Id: I31d60ea182226c032b0ffbddcbb5b53675dfd5e6
Reviewed-on: https://go-review.googlesource.com/c/sync/+/660075
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: Alan Donovan <[email protected]>
Auto-Submit: Damien Neil <[email protected]>
Reviewed-by: Damien Neil <[email protected]>

errgroup: drop support for Go versions before 1.20

Change-Id: I7de5dfae21c4ffe31d6c16e3df0fed3e2269cb16
Reviewed-on: https://go-review.googlesource.com/c/sync/+/654421
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: Ian Lance Taylor <[email protected]>
Auto-Submit: Ian Lance Taylor <[email protected]>
Commit-Queue: Ian Lance Taylor <[email protected]>
Reviewed-by: Dmitri Shuralyov <[email protected]>
Reviewed-by: Dmitri Shuralyov <[email protected]>

sync/errgroup: improve documentation for semaphore limit behavior

Updated the documentation for `SetLimit` and `Go` functions in the
`errgroup` package. the note clarifies the behavior when the semaphore
limit is set to zero, which could lead to a deadlock if not handled
properly. the updated documentation warns users to set a positive
semaphore limit to avoid blocking goroutines and potential deadlock

this change improves the clarity of API and helps users understand how
to properly use the semaphore limit to prevent issues in concurrent
execution

Change-Id: Ie62acc38ef804b3590c04bddba00a3cce21e8cef
Reviewed-on: https://go-review.googlesource.com/c/sync/+/642215
Reviewed-by: Michael Knyszek <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: Ian Lance Taylor <[email protected]>
Auto-Submit: Ian Lance Taylor <[email protected]>

singleflight: fix typo in singleflight_test.go

Change-Id: Ia2160fdc8f1938d784a4e1595151c00bc521f5c3
Reviewed-on: https://go-review.googlesource.com/c/sync/+/626795
TryBot-Result: Gopher Robot <[email protected]>
Auto-Submit: Ian Lance Taylor <[email protected]>
Run-TryBot: Emmanuel Odeke <[email protected]>
Commit-Queue: Ian Lance Taylor <[email protected]>
Reviewed-by: Emmanuel Odeke <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>
Auto-Submit: Emmanuel Odeke <[email protected]>
Reviewed-by: Ian Lance Taylor <[email protected]>
Reviewed-by: Alan Donovan <[email protected]>
Reviewed-by: Cherry Mui <[email protected]>

README: don't recommend go get

These days people will just import the packages and the go tool will
do the right thing. We don't need to explain it.

Add a pointer to the git repo, though.

For golang/go#62645

Change-Id: Icbe33e05f96e1b32f6fcc99fb5fb0b2ecb213a08
Reviewed-on: https://go-review.googlesource.com/c/sync/+/623820
Commit-Queue: Ian Lance Taylor <[email protected]>
Auto-Submit: Ian Lance Taylor <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: Alan Donovan <[email protected]>
Reviewed-by: Ian Lance Taylor <[email protected]>

LICENSE: update per Google Legal

Very minor tweaks:
 - Remove (c) pseudosymbol.
 - Remove "All Rights Reserved."
 - Change "Google Inc." (no longer exists) to "Google LLC".

[git-generate]
echo '
,s/\(c\) //
,s/ All rights reserved.//
,s/Google Inc./Google LLC/
w
q
' | sam -d LICENSE

Change-Id: Ifc1b84adca131018a48ba47e741a682a0ed9bb49
Reviewed-on: https://go-review.googlesource.com/c/sync/+/598584
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: Ian Lance Taylor <[email protected]>
Auto-Submit: Russ Cox <[email protected]>

semaphore: cancel acquisition with a done context

When acquiring from a semaphore could proceed without contention, the
previous behavior was to always do so, even when the provided context
was done. This was the documented behavior, but it could lead to
confusion. It isn't much more expensive to check the context error, so
cancel acquisition if it's done.

Fixes golang/go#63615.

goos: linux
goarch: amd64
pkg: golang.org/x/sync/semaphore
cpu: 12th Gen Intel(R) Core(TM) i5-1235U
                                        │  old.bench  │             new.bench              │
                                        │   sec/op    │   sec/op     vs base               │
AcquireSeq/Weighted-acquire-1-1-1-12      26.45n ± 2%   27.25n ± 3%  +3.04% (p=0.001 n=20)
AcquireSeq/Weighted-acquire-2-1-1-12      26.96n ± 1%   27.12n ± 1%       ~ (p=0.104 n=20)
AcquireSeq/Weighted-acquire-16-1-1-12     26.07n ± 3%   27.48n ± 1%  +5.45% (p=0.000 n=20)
AcquireSeq/Weighted-acquire-128-1-1-12    26.19n ± 2%   27.24n ± 1%  +4.01% (p=0.000 n=20)
AcquireSeq/Weighted-acquire-2-2-1-12      25.61n ± 1%   25.99n ± 2%       ~ (p=0.066 n=20)
AcquireSeq/Weighted-acquire-16-2-8-12     209.6n ± 2%   211.0n ± 3%       ~ (p=0.280 n=20)
AcquireSeq/Weighted-acquire-128-2-64-12   1.669µ ± 1%   1.721µ ± 2%  +3.09% (p=0.000 n=20)
AcquireSeq/Weighted-acquire-2-1-2-12      51.08n ± 1%   53.03n ± 2%  +3.82% (p=0.000 n=20)
AcquireSeq/Weighted-acquire-16-8-2-12     52.48n ± 2%   53.66n ± 2%  +2.26% (p=0.028 n=20)
AcquireSeq/Weighted-acquire-128-64-2-12   52.27n ± 1%   53.71n ± 2%  +2.75% (p=0.000 n=20)
geomean                                   60.06n        61.69n       +2.71%

Change-Id: I0ae1a0bb6c027461ac1a9ee71c51efd8427ab308
Reviewed-on: https://go-review.googlesource.com/c/sync/+/536275
Auto-Submit: Bryan Mills <[email protected]>
Reviewed-by: Bryan Mills <[email protected]>
Reviewed-by: Michael Knyszek <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>

errgroup: add reference to sync.WaitGroup

Add doc link to sync.WaitGroup in the package documentation.

Rationale:
The reference to sync.WaitGroup might be obvious to the authors of this
package, but it wasn't to me, so despites I had seen this package
multiple times I had never made the link to sync.WaitGroup. So when
playing with WaitGroup I was missing remembering about errgroup.
In hope this will help others as well as my future self.

Change-Id: I2c56976958ad9ab94c1596c96fa86c00dd73d2fb
Reviewed-on: https://go-review.googlesource.com/c/sync/+/538335
Reviewed-by: Bryan Mills <[email protected]>
Reviewed-by: Carlos Amedee <[email protected]>
Auto-Submit: Bryan Mills <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>