120 lines
2.7 KiB
Go
120 lines
2.7 KiB
Go
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package semaphore
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// Based on https://github.com/golang/sync/blob/master/semaphore/semaphore_test.go
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import (
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"context"
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"math/rand"
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"runtime"
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"sync"
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"testing"
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"time"
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"github.com/stretchr/testify/require"
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)
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const maxSleep = 1 * time.Millisecond
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func HammerDynamic(sem *Dynamic, loops int) {
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for i := 0; i < loops; i++ {
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sem.Acquire(context.Background())
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time.Sleep(time.Duration(rand.Int63n(int64(maxSleep/time.Nanosecond))) * time.Nanosecond)
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sem.Release()
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}
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}
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// TestDynamic hammers the semaphore from all available cores to ensure we don't
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// hit a panic or race detector notice something wonky.
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func TestDynamic(t *testing.T) {
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t.Parallel()
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n := runtime.GOMAXPROCS(0)
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loops := 10000 / n
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sem := NewDynamic(int64(n))
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var wg sync.WaitGroup
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wg.Add(n)
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for i := 0; i < n; i++ {
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go func() {
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defer wg.Done()
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HammerDynamic(sem, loops)
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}()
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}
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wg.Wait()
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}
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func TestDynamicPanic(t *testing.T) {
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t.Parallel()
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defer func() {
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if recover() == nil {
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t.Fatal("release of an unacquired dynamic semaphore did not panic")
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}
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}()
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w := NewDynamic(1)
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w.Release()
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}
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func checkAcquire(t *testing.T, sem *Dynamic, wantAcquire bool) {
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t.Helper()
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ctx, cancel := context.WithTimeout(context.Background(), 10*time.Millisecond)
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defer cancel()
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err := sem.Acquire(ctx)
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if wantAcquire {
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require.NoErrorf(t, err, "failed to acquire when we should have")
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} else {
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require.Error(t, err, "failed to block when should be full")
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}
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}
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func TestDynamicAcquire(t *testing.T) {
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t.Parallel()
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ctx := context.Background()
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sem := NewDynamic(2)
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// Consume one slot [free: 1]
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sem.Acquire(ctx)
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// Should be able to consume another [free: 0]
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checkAcquire(t, sem, true)
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// Should fail to consume another [free: 0]
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checkAcquire(t, sem, false)
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// Release 2
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sem.Release()
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sem.Release()
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// Should be able to consume another [free: 1]
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checkAcquire(t, sem, true)
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// Should be able to consume another [free: 0]
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checkAcquire(t, sem, true)
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// Should fail to consume another [free: 0]
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checkAcquire(t, sem, false)
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// Now expand the semaphore and we should be able to acquire again [free: 2]
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sem.SetSize(4)
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// Should be able to consume another [free: 1]
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checkAcquire(t, sem, true)
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// Should be able to consume another [free: 0]
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checkAcquire(t, sem, true)
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// Should fail to consume another [free: 0]
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checkAcquire(t, sem, false)
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// Shrinking it should work [free: 0]
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sem.SetSize(3)
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// Should fail to consume another [free: 0]
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checkAcquire(t, sem, false)
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// Release one [free: 0] (3 slots used are release, size only 3)
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sem.Release()
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// Should fail to consume another [free: 0]
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checkAcquire(t, sem, false)
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sem.Release()
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// Should be able to consume another [free: 1]
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checkAcquire(t, sem, true)
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}
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