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>
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>
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>
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>
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>
