85 lines
2 KiB
Go
85 lines
2 KiB
Go
package vault
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import (
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"fmt"
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"math/rand"
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"sync"
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"sync/atomic"
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"testing"
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"time"
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)
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// TestGrabLockOrStopped is a non-deterministic test to detect deadlocks in the
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// grabLockOrStopped function. This test starts a bunch of workers which
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// continually lock/unlock and rlock/runlock the same RWMutex. Each worker also
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// starts a goroutine which closes the stop channel 1/2 the time, which races
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// with acquisition of the lock.
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func TestGrabLockOrStop(t *testing.T) {
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// Stop the test early if we deadlock.
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const (
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workers = 100
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testDuration = time.Second
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testTimeout = 10 * testDuration
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)
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done := make(chan struct{})
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defer close(done)
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var lockCount int64
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go func() {
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select {
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case <-done:
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case <-time.After(testTimeout):
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panic(fmt.Sprintf("deadlock after %d lock count",
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atomic.LoadInt64(&lockCount)))
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}
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}()
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// lock is locked/unlocked and rlocked/runlocked concurrently.
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var lock sync.RWMutex
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start := time.Now()
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// workerWg is used to wait until all workers exit.
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var workerWg sync.WaitGroup
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workerWg.Add(workers)
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// Start a bunch of worker goroutines.
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for g := 0; g < workers; g++ {
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g := g
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go func() {
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defer workerWg.Done()
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for time.Now().Sub(start) < testDuration {
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stop := make(chan struct{})
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// closerWg waits until the closer goroutine exits before we do
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// another iteration. This makes sure goroutines don't pile up.
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var closerWg sync.WaitGroup
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closerWg.Add(1)
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go func() {
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defer closerWg.Done()
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// Close the stop channel half the time.
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if rand.Int()%2 == 0 {
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close(stop)
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}
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}()
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// Half the goroutines lock/unlock and the other half rlock/runlock.
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if g%2 == 0 {
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if !grabLockOrStop(lock.Lock, lock.Unlock, stop) {
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lock.Unlock()
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}
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} else {
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if !grabLockOrStop(lock.RLock, lock.RUnlock, stop) {
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lock.RUnlock()
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}
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}
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closerWg.Wait()
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// This lets us know how many lock/unlock and rlock/runlock have
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// happened if there's a deadlock.
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atomic.AddInt64(&lockCount, 1)
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}
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}()
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}
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workerWg.Wait()
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}
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