Commit Graph

37 Commits

Author SHA1 Message Date
Joe Tsai 5db80cf2d8
syncs: fix AtomicValue for interface kinds (#11943)
If AtomicValue[T] is used with a T that is an interface kind,
then Store may panic if different concret types are ever stored.

Fix this by always wrapping in a concrete type.
Technically, this is only needed if T is an interface kind,
but there is no harm in doing it also for non-interface kinds.

Updates #cleanup

Signed-off-by: Joe Tsai <joetsai@digital-static.net>
2024-04-30 14:27:58 -07:00
Brad Fitzpatrick c07aa2cfed syncs: fix flaky test by deleting the code it tested (Watch)
Fixes #11766

Change-Id: Id5a875aab23eb1b48a57dc379d0cdd42412fd18b
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2024-04-22 21:16:14 -07:00
Brad Fitzpatrick 7c1d6e35a5 all: use Go 1.22 range-over-int
Updates #11058

Change-Id: I35e7ef9b90e83cac04ca93fd964ad00ed5b48430
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2024-04-16 15:32:38 -07:00
Andrew Dunham e382e4cee6 syncs: add Swap method
To mimic sync.Map.Swap, sync/atomic.Value.Swap, etc.

Updates tailscale/corp#1297

Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: If7627da1bce8b552873b21d7e5ebb98904e9a650
2024-03-19 18:39:44 -04:00
Uri Gorelik b88929edf8 Fix potential goroutine leak in syncs/watchdog.go
Depending on how the preemption will occur, in some scenarios sendc
would have blocked indefinitely even after cancelling the context.

Fixes #10315

Signed-off-by: Uri Gorelik <uri.gore@gmail.com>
2023-11-18 10:37:29 -08:00
Joe Tsai 674beabc73
syncs: add Map.LoadFunc (#9869)
The LoadFunc loads a value and calls a user-provided function.
The utility of this method is to ensure that the map lock is held
while executing user-provided logic.
This allows us to solve TOCTOU bugs that would be nearly imposible
to the solve without this API.

Updates tailscale/corp#14772

Signed-off-by: Joe Tsai <joetsai@digital-static.net>
2023-10-18 15:02:45 -07:00
James Tucker 498f7ec663 syncs: add Map.LoadOrInit for lazily initialized values
I was reviewing some code that was performing this by hand, and wanted
to suggest using syncs.Map, however as the code in question was
allocating a non-trivial structure this would be necessary to meet the
target.

Updates #cleanup

Signed-off-by: James Tucker <james@tailscale.com>
2023-10-06 17:06:11 -07:00
Brad Fitzpatrick e8551d6b40 all: use Go 1.21 slices, maps instead of x/exp/{slices,maps}
Updates #8419

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2023-08-17 08:42:35 -07:00
Denton Gentry 7e15c78a5a syncs: add map.Clear() method
Updates https://github.com/tailscale/corp/issues/13979

Signed-off-by: Denton Gentry <dgentry@tailscale.com>
2023-08-17 08:02:56 -07:00
Brad Fitzpatrick cafd9a2bec syncs: add ShardedMap.Mutate
To let callers do atomic/CAS-like operations.

Updates tailscale/corp#7355

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2023-06-28 08:43:15 -07:00
Brad Fitzpatrick ba41d14320 syncs: add ShardedMap type
Updates tailscale/corp#7354

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2023-06-25 12:51:19 -07:00
James Tucker b3c3a9f174 syncs: add Map.Len to get the length of the Map
I need this for a corp change where I have a set as a queue, and make a
different decisison if the set is empty.

Updates tailscale/corp#10344

Signed-off-by: James Tucker <james@tailscale.com>
2023-04-27 19:10:28 -07:00
James Tucker d35ce1add9 syncs: add documentation to Map.Range
Updates #cleanup

Signed-off-by: James Tucker <james@tailscale.com>
2023-04-27 17:07:07 -07:00
James Tucker cd35a79136 syncs: relax TestWatchMultipleValues timing on Windows
The test is re-enabled for Windows with a relaxed time assertion.

On Windows the runtime poller currently does not have sufficient
resolution to meet the normal requirements for this test.

See https://github.com/golang/go/issues/44343 for background.

Updates #7876

Signed-off-by: James Tucker <jftucker@gmail.com>
2023-04-19 19:00:34 -07:00
James Tucker 8dec1a8724 .github/workflows: reenable Windows CI, disable broken tests
We accidentally switched to ./tool/go in
4022796484 which resulted in no longer
running Windows builds, as this is attempting to run a bash script.

I was unable to quickly fix the various tests that have regressed, so
instead I've added skips referencing #7876, which we need to back and
fix.

Updates #7262
Updates #7876

Signed-off-by: James Tucker <james@tailscale.com>
2023-04-14 14:13:53 -07:00
Joe Tsai dad78f31f3
syncs: add WaitGroup wrapper (#7481)
The addition of WaitGroup.Go in the standard library has been
repeatedly proposed and rejected.
See golang/go#18022, golang/go#23538, and golang/go#39863

In summary, the argument for WaitGroup.Go is that it avoids bugs like:

	go func() {
		wg.Add(1)
		defer wg.Done()
		...
	}()

where the increment happens after execution (not before)
and also (to a lesser degree) because:

	wg.Go(func() {
		...
	})

is shorter and more readble.

The argument against WaitGroup.Go is that the provided function
takes no arguments and so inputs and outputs must closed over
by the provided function. The most common race bug for goroutines
is that the caller forgot to capture the loop iteration variable,
so this pattern may make it easier to be accidentally racy.
However, that is changing with golang/go#57969.

In my experience the probability of race bugs due to the former
still outwighs the latter, but I have no concrete evidence to prove it.

The existence of errgroup.Group.Go and frequent utility of the method
at least proves that this is a workable pattern and
the possibility of accidental races do not appear to
manifest as frequently as feared.

A reason *not* to use errgroup.Group everywhere is that there are many
situations where it doesn't make sense for the goroutine to return an error
since the error is handled in a different mechanism
(e.g., logged and ignored, formatted and printed to the frontend, etc.).
While you can use errgroup.Group by always returning nil,
the fact that you *can* return nil makes it easy to accidentally return
an error when nothing is checking the return of group.Wait.
This is not a hypothetical problem, but something that has bitten us
in usages that was only using errgroup.Group without intending to use
the error reporting part of it.

Thus, add a (yet another) variant of WaitGroup here that
is identical to sync.WaitGroup, but with an extra method.

Signed-off-by: Joe Tsai <joetsai@digital-static.net>
2023-03-09 12:04:38 -08:00
Denton Gentry 9ab992e7a1 syncs: re-enable TestWatchMultipleValues
We've updated to a different set of CI machines since this test
was disabled.

Fixes https://github.com/tailscale/tailscale/issues/1513

Signed-off-by: Denton Gentry <dgentry@tailscale.com>
2023-02-25 17:03:16 -08:00
Will Norris 71029cea2d all: update copyright and license headers
This updates all source files to use a new standard header for copyright
and license declaration.  Notably, copyright no longer includes a date,
and we now use the standard SPDX-License-Identifier header.

This commit was done almost entirely mechanically with perl, and then
some minimal manual fixes.

Updates #6865

Signed-off-by: Will Norris <will@tailscale.com>
2023-01-27 15:36:29 -08:00
Joe Tsai 9a05cdd2b5
syncs: add Map (#6260)
Map is a concurrent safe map that is a trivial wrapper
over a Go map and a sync.RWMutex.

It is optimized for use-cases where the entries change often,
which is the opposite use-case of what sync.Map is optimized for.

The API is patterned off of sync.Map, but made generic.

Signed-off-by: Joe Tsai <joetsai@digital-static.net>
2022-11-10 10:55:26 -08:00
Brad Fitzpatrick da8def8e13 all: remove old +build tags
The //go:build syntax was introduced in Go 1.17:

https://go.dev/doc/go1.17#build-lines

gofmt has kept the +build and go:build lines in sync since
then, but enough time has passed. Time to remove them.

Done with:

    perl -i -npe 's,^// \+build.*\n,,' $(git grep -l -F '+build')

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2022-11-04 07:25:42 -07:00
Maisem Ali b75f81ec00 syncs: add generic AtomicValue
Signed-off-by: Maisem Ali <maisem@tailscale.com>
2022-08-04 11:52:16 -07:00
Brad Fitzpatrick 4950fe60bd syncs, all: move to using Go's new atomic types instead of ours
Fixes #5185

Change-Id: I850dd532559af78c3895e2924f8237ccc328449d
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2022-08-04 07:47:59 -07:00
Josh Bleecher Snyder 997b19545b syncs: use TryLock and TryRLock instead of unsafe
The docs say:

Note that while correct uses of TryLock do exist, they are rare,
and use of TryLock is often a sign of a deeper problem in a particular use of mutexes.

Rare code! Or bad code! Who can tell!

Signed-off-by: Josh Bleecher Snyder <josh@tailscale.com>
2022-03-17 10:57:41 -07:00
Josh Bleecher Snyder cf8fcc1254 syncs: mark as safe for Go 1.18
Signed-off-by: Josh Bleecher Snyder <josh@tailscale.com>
2021-10-27 18:10:09 -07:00
Josh Bleecher Snyder d2aa144dcc syncs: bump known good version to include Go 1.17
Signed-off-by: Josh Bleecher Snyder <josh@tailscale.com>
2021-08-17 11:13:03 -07:00
Josh Bleecher Snyder a5da4ed981 all: gofmt with Go 1.17
This adds "//go:build" lines and tidies up existing "// +build" lines.

Signed-off-by: Josh Bleecher Snyder <josh@tailscale.com>
2021-08-05 15:54:00 -07:00
Brad Fitzpatrick e4fecfe31d wgengine/{monitor,router}: restore Linux ip rules when systemd deletes them
Thanks.

Fixes #1591

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2021-07-20 15:52:22 -07:00
David Crawshaw 676e32ad72 syncs: add AtomicUint32
Signed-off-by: David Crawshaw <crawshaw@tailscale.com>
2021-06-23 08:51:37 -07:00
David Crawshaw 297b3d6fa4 staticcheck.conf: turn off noisy lint errors
Signed-off-by: David Crawshaw <crawshaw@tailscale.com>
2021-06-18 15:48:20 -07:00
Josh Bleecher Snyder d3ba860ffd syncs: stop running TestWatchMultipleValues on CI
It's flaky, and not just on Windows.

Signed-off-by: Josh Bleecher Snyder <josharian@gmail.com>
2021-05-04 10:21:21 -07:00
Josh Bleecher Snyder 0807e3e2f7 syncs: disable TestWatchMultipleValues on Windows CI builds
The Windows CI machine experiences significant random execution delays.
For example, in this code from watchdog.go:

done := make(chan bool)
go func() {
	start := time.Now()
	mu.Lock()

There was a 500ms delay from initializing done to locking mu.

This test checks that we receive a sufficient number of events quickly enough.
In the face of random 500ms delays, unsurprisingly, the test fails.

There's not much principled we can do about it.
We could build a system of retries or attempt to detect these random delays,
but that game isn't worth the candle.

Skip the test.

Signed-off-by: Josh Bleecher Snyder <josh@tailscale.com>
2021-03-27 13:25:33 -07:00
Brad Fitzpatrick 77ec80538a syncs: add Semaphore
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2021-03-23 12:39:28 -07:00
Dmytro Tananayskiy c431382720 Fix receiver in order to be consistent: syncs.WaitGroupChan
Signed-off-by: Dmytro Tananayskiy <dmitriyminer@gmail.com>
2020-11-24 17:20:34 -08:00
Josh Bleecher Snyder 9ab2b32569 syncs: add Watch, for monitoring mutex contention
Signed-off-by: Josh Bleecher Snyder <josh@tailscale.com>
2020-09-11 11:36:07 -07:00
Josh Bleecher Snyder bf24d54143 syncs: add AssertLocked
This allows us to check lock invariants.

It was proposed upstream and rejected in:
https://github.com/golang/go/issues/1366

Signed-off-by: Josh Bleecher Snyder <josh@tailscale.com>
2020-09-09 12:27:52 -07:00
Brad Fitzpatrick d3134ad0c8 syncs: add AtomicBool 2020-05-29 12:41:30 -07:00
Brad Fitzpatrick b4d02a251a syncs: add new package for extra sync types 2020-03-12 11:13:33 -07:00