add AcquireWithTimeout for semaphores

irc/utils/semaphores_test.go

@@ -0,0 +1,48 @@
+// Copyright (c) 2019 Shivaram Lingamneni
+// released under the MIT license
+
+package utils
+
+import (
+	"testing"
+	"time"
+)
+
+func TestTryAcquire(t *testing.T) {
+	count := 3
+	var sem Semaphore
+	sem.Initialize(count)
+
+	for i := 0; i < count; i++ {
+		assertEqual(sem.TryAcquire(), true, t)
+	}
+	// used up the capacity
+	assertEqual(sem.TryAcquire(), false, t)
+	sem.Release()
+	// got one slot back
+	assertEqual(sem.TryAcquire(), true, t)
+}
+
+func TestAcquireWithTimeout(t *testing.T) {
+	var sem Semaphore
+	sem.Initialize(1)
+
+	assertEqual(sem.TryAcquire(), true, t)
+
+	// cannot acquire the held semaphore
+	assertEqual(sem.AcquireWithTimeout(100*time.Millisecond), false, t)
+
+	sem.Release()
+	// can acquire the released semaphore
+	assertEqual(sem.AcquireWithTimeout(100*time.Millisecond), true, t)
+	sem.Release()
+
+	// XXX this test could fail if the machine is extremely overloaded
+	sem.Acquire()
+	go func() {
+		time.Sleep(100 * time.Millisecond)
+		sem.Release()
+	}()
+	// we should acquire successfully after approximately 100 msec
+	assertEqual(sem.AcquireWithTimeout(1*time.Second), true, t)
+}