tailscale

Commit Graph

Author	SHA1	Message	Date
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>	2 years ago
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>	2 years ago
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>	2 years ago
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>	2 years ago
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>	2 years ago
Maisem Ali	b75f81ec00	syncs: add generic AtomicValue Signed-off-by: Maisem Ali <maisem@tailscale.com>	2 years ago
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>	2 years ago
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>	3 years ago
Josh Bleecher Snyder	cf8fcc1254	syncs: mark as safe for Go 1.18 Signed-off-by: Josh Bleecher Snyder <josh@tailscale.com>	3 years ago
Josh Bleecher Snyder	d2aa144dcc	syncs: bump known good version to include Go 1.17 Signed-off-by: Josh Bleecher Snyder <josh@tailscale.com>	3 years ago
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>	3 years ago
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>	3 years ago
David Crawshaw	676e32ad72	syncs: add AtomicUint32 Signed-off-by: David Crawshaw <crawshaw@tailscale.com>	3 years ago
David Crawshaw	297b3d6fa4	staticcheck.conf: turn off noisy lint errors Signed-off-by: David Crawshaw <crawshaw@tailscale.com>	3 years ago
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>	4 years ago
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>	4 years ago
Brad Fitzpatrick	77ec80538a	syncs: add Semaphore Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>	4 years ago
Dmytro Tananayskiy	c431382720	Fix receiver in order to be consistent: syncs.WaitGroupChan Signed-off-by: Dmytro Tananayskiy <dmitriyminer@gmail.com>	4 years ago
Josh Bleecher Snyder	9ab2b32569	syncs: add Watch, for monitoring mutex contention Signed-off-by: Josh Bleecher Snyder <josh@tailscale.com>	4 years ago
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>	4 years ago
Brad Fitzpatrick	d3134ad0c8	syncs: add AtomicBool	5 years ago
Brad Fitzpatrick	b4d02a251a	syncs: add new package for extra sync types	5 years ago

22 Commits (8c2b755b2e357ffb972880d24c0b18e13d97f662)