open-consul/lib/semaphore/semaphore_test.go

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