// =================================================================================================
// Copyright 2011 Twitter, Inc.
// -------------------------------------------------------------------------------------------------
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this work except in compliance with the License.
// You may obtain a copy of the License in the LICENSE file, or at:
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// =================================================================================================
package com.twitter.common.net.loadbalancing;
import com.google.common.collect.Sets;
import com.twitter.common.base.Closure;
import com.twitter.common.testing.EasyMockTest;
import com.twitter.common.net.pool.ResourceExhaustedException;
import org.easymock.Capture;
import org.junit.Before;
import org.junit.Test;
import java.util.Collection;
import java.util.HashSet;
import java.util.Set;
import static org.easymock.EasyMock.capture;
import static org.hamcrest.CoreMatchers.is;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertThat;
import static org.junit.Assert.assertTrue;
import static org.junit.Assert.fail;
/**
* @author William Farner
*/
public class RoundRobinStrategyTest extends EasyMockTest {
private static final String BACKEND_1 = "backend1";
private static final String BACKEND_2 = "backend2";
private static final String BACKEND_3 = "backend3";
private Closure<Collection<String>> onBackendsChosen;
private LoadBalancingStrategy<String> roundRobin;
@Before
public void setUp() {
onBackendsChosen = createMock(new Clazz<Closure<Collection<String>>>() {});
roundRobin = new RoundRobinStrategy<String>();
}
@Test(expected = ResourceExhaustedException.class)
public void testNoBackends() throws ResourceExhaustedException {
control.replay();
roundRobin.nextBackend();
}
@Test
public void testEmptyBackends() throws ResourceExhaustedException {
Capture<Collection<String>> capture = createCapture();
onBackendsChosen.execute(capture(capture));
control.replay();
roundRobin.offerBackends(Sets.<String>newHashSet(), onBackendsChosen);
try {
roundRobin.nextBackend();
fail("Expected ResourceExhaustedException to be thrown");
} catch (ResourceExhaustedException e) {
// expected
}
assertTrue(capture.hasCaptured());
assertTrue(capture.getValue().isEmpty());
}
@Test
public void testConsistentOrdering() throws ResourceExhaustedException {
Capture<Collection<String>> capture = createCapture();
onBackendsChosen.execute(capture(capture));
control.replay();
HashSet<String> backends = Sets.newHashSet(BACKEND_1, BACKEND_2, BACKEND_3);
roundRobin.offerBackends(backends, onBackendsChosen);
Set<String> iteration1 = Sets.newHashSet(
roundRobin.nextBackend(),
roundRobin.nextBackend(),
roundRobin.nextBackend()
);
Set<String> iteration2 = Sets.newHashSet(
roundRobin.nextBackend(),
roundRobin.nextBackend(),
roundRobin.nextBackend()
);
assertThat(iteration2, is(iteration1));
assertTrue(capture.hasCaptured());
assertEquals(backends, Sets.newHashSet(capture.getValue()));
}
}