/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License 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 org.apache.hadoop.ha;
import org.junit.Assert;
/**
* A fake shared resource, for use in automatic failover testing.
* This simulates a real shared resource like a shared edit log.
* When the {@link DummyHAService} instances change state or get
* fenced, they notify the shared resource, which asserts that
* we never have two HA services who think they're holding the
* resource at the same time.
*/
public class DummySharedResource {
private DummyHAService holder = null;
private int violations = 0;
public synchronized void take(DummyHAService newHolder) {
if (holder == null || holder == newHolder) {
holder = newHolder;
} else {
violations++;
throw new IllegalStateException("already held by: " + holder);
}
}
public synchronized void release(DummyHAService oldHolder) {
if (holder == oldHolder) {
holder = null;
}
}
public synchronized void assertNoViolations() {
Assert.assertEquals(0, violations);
}
}