hubble: Fix data races in pkg/hubble.TestRingReader_NextFollow_WithEmptyRing
#17397
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The NextFollow method writes to `r.followChan` variable concurrently
from a `go func() {..}` statement when the context is cancelled. That
write may be executed concurrently to the other accesses in NextFollow.
This commit fixes that issue by protecting the access with a mutex.
Signed-off-by: Sebastian Wicki <sebastian@isovalent.com>
The ring reader unit tests rely on wait groups to ensure all go routines spawned by `NextFollow` have exited. However, correct use requires us to ensure that there are no concurrent spawns while we wait, i.e. it is an error to invoke `Close` concurrently to `NextFollow`, one must wait for `NextFollow` to return and then wait for any still lingering Go routines to finish. See the documentation of WaitGroup.Add for details: https://pkg.go.dev/sync#WaitGroup.Add This fixes an issue reported by the Go race detector by ensuring NextFollow has exited before we wait on any lingering go routines. Signed-off-by: Sebastian Wicki <sebastian@isovalent.com>
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Sep 14, 2021
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This fixes two unit test data races reported in #17255 - see commit messages for details. Both races were easy to reproduce locally via
go test -race -count 10 .insidepkg/hubble/container. I have verified that the races are fixed by runninggo test -race -count 1000 .Fixes: #17255