/**
* 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.hbase.conf;
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertTrue;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.testclassification.ClientTests;
import org.apache.hadoop.hbase.testclassification.SmallTests;
import org.junit.Test;
import org.junit.experimental.categories.Category;
@Category({SmallTests.class, ClientTests.class})
public class TestConfigurationManager {
private static final Log LOG = LogFactory.getLog(TestConfigurationManager.class);
class DummyConfigurationObserver implements ConfigurationObserver {
private boolean notifiedOnChange = false;
private ConfigurationManager cm;
public DummyConfigurationObserver(ConfigurationManager cm) {
this.cm = cm;
register();
}
public void onConfigurationChange(Configuration conf) {
notifiedOnChange = true;
}
// Was the observer notified on Configuration change?
public boolean wasNotifiedOnChange() {
return notifiedOnChange;
}
public void resetNotifiedOnChange() {
notifiedOnChange = false;
}
public void register() {
this.cm.registerObserver(this);
}
public void deregister() {
this.cm.deregisterObserver(this);
}
}
/**
* Test if observers get notified by the <code>ConfigurationManager</code>
* when the Configuration is reloaded.
*/
@Test
public void testCheckIfObserversNotified() {
Configuration conf = new Configuration();
ConfigurationManager cm = new ConfigurationManager();
DummyConfigurationObserver d1 = new DummyConfigurationObserver(cm);
// Check if we get notified.
cm.notifyAllObservers(conf);
assertTrue(d1.wasNotifiedOnChange());
d1.resetNotifiedOnChange();
// Now check if we get notified on change with more than one observers.
DummyConfigurationObserver d2 = new DummyConfigurationObserver(cm);
cm.notifyAllObservers(conf);
assertTrue(d1.wasNotifiedOnChange());
d1.resetNotifiedOnChange();
assertTrue(d2.wasNotifiedOnChange());
d2.resetNotifiedOnChange();
// Now try deregistering an observer and verify that it was not notified
d2.deregister();
cm.notifyAllObservers(conf);
assertTrue(d1.wasNotifiedOnChange());
d1.resetNotifiedOnChange();
assertFalse(d2.wasNotifiedOnChange());
}
// Register an observer that will go out of scope immediately, allowing
// us to test that out of scope observers are deregistered.
private void registerLocalObserver(ConfigurationManager cm) {
new DummyConfigurationObserver(cm);
}
/**
* Test if out-of-scope observers are deregistered on GC.
*/
@Test
public void testDeregisterOnOutOfScope() {
Configuration conf = new Configuration();
ConfigurationManager cm = new ConfigurationManager();
boolean outOfScopeObserversDeregistered = false;
// On my machine, I was able to cause a GC after around 5 iterations.
// If we do not cause a GC in 100k iterations, which is very unlikely,
// there might be something wrong with the GC.
for (int i = 0; i < 100000; i++) {
registerLocalObserver(cm);
cm.notifyAllObservers(conf);
// 'Suggest' the system to do a GC. We should be able to cause GC
// atleast once in the 2000 iterations.
System.gc();
// If GC indeed happened, all the observers (which are all out of scope),
// should have been deregistered.
if (cm.getNumObservers() <= i) {
outOfScopeObserversDeregistered = true;
break;
}
}
if (!outOfScopeObserversDeregistered) {
LOG.warn("Observers were not GC-ed! Something seems to be wrong.");
}
assertTrue(outOfScopeObserversDeregistered);
}
}