@Test
public void nextZeroWeight() {
Balancer<Void, MockDatabase> balancer =
this.factory.createBalancer(Collections.singleton(this.databases[0]));
assertSame(this.databases[0], balancer.next());
}
@Test
public void nextEmptyBalancer() {
Balancer<Void, MockDatabase> balancer =
this.factory.createBalancer(Collections.<MockDatabase>emptySet());
assertNull(balancer.next());
}
@Test
public void nextSingleWeight() {
Balancer<Void, MockDatabase> balancer =
this.factory.createBalancer(
new HashSet<MockDatabase>(Arrays.asList(this.databases[0], this.databases[1])));
assertSame(this.databases[1], balancer.next());
int count = 10;
CountDownLatch latch = new CountDownLatch(count);
WaitingInvoker invoker = new WaitingInvoker(latch);
ExecutorService executor = Executors.newFixedThreadPool(count);
List<Future<Void>> futures = new ArrayList<Future<Void>>(count);
for (int i = 0; i < count; ++i) {
futures.add(executor.submit(new InvocationTask(balancer, invoker, this.databases[1])));
}
try {
// Ensure all invokers are started
latch.await();
// Should still use the same database, even under load
assertSame(this.databases[1], balancer.next());
// Allow invokers to continue
synchronized (invoker) {
invoker.notifyAll();
}
this.complete(futures);
// Should still use the same database, after load
assertSame(this.databases[1], balancer.next());
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
} finally {
executor.shutdownNow();
}
}