/*
* Copyright 2009-2010 Rickard Öberg AB
*
* Licensed 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.qi4j.library.circuitbreaker;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.beans.PropertyVetoException;
import java.beans.VetoableChangeListener;
import java.io.IOException;
import java.util.concurrent.Callable;
import org.hamcrest.CoreMatchers;
import org.junit.Before;
import org.junit.Test;
import static com.jayway.awaitility.Awaitility.await;
import static com.jayway.awaitility.Duration.FIVE_HUNDRED_MILLISECONDS;
import static org.hamcrest.core.Is.is;
import static org.junit.Assert.assertThat;
/**
* JAVADOC
*/
public class CircuitBreakerTest
{
private CircuitBreaker cb;
@Before
public void createCircuitBreaker()
{
// START SNIPPET: direct
// Create a CircuitBreaker with a threshold of 3, a 250ms timeout, allowing IllegalArgumentExceptions
CircuitBreaker cb = new CircuitBreaker( 3, 250, CircuitBreakers.in( IllegalArgumentException.class ) );
// END SNIPPET: direct
cb.addPropertyChangeListener( new PropertyChangeListener()
{
public void propertyChange( PropertyChangeEvent evt )
{
System.out.println( evt.getSource() + ":" + evt.getPropertyName() + "=" + evt.getOldValue() + " -> " + evt.getNewValue() );
}
} );
this.cb = cb;
}
@Test
public void GivenCBWhenTripWithExceptionsAndTurnOnThenStatusIsOn()
throws PropertyVetoException
{
assertThat( cb.status(), CoreMatchers.equalTo( CircuitBreaker.Status.on ) );
// START SNIPPET: direct
// Service levels goes down but does not cause a trip
cb.throwable( new IOException() );
// END SNIPPET: direct
assertThat( cb.status(), CoreMatchers.equalTo( CircuitBreaker.Status.on ) );
// START SNIPPET: direct
// Service level goes down and causes a trip
cb.throwable( new IOException() );
cb.throwable( new IOException() );
// END SNIPPET: direct
assertThat( cb.status(), CoreMatchers.equalTo( CircuitBreaker.Status.off ) );
// START SNIPPET: direct
// Turn on the CB again
cb.turnOn();
// END SNIPPET: direct
assertThat( cb.status(), CoreMatchers.equalTo( CircuitBreaker.Status.on ) );
}
@Test
public void GivenCBWhenAllowedExceptionsThenServiceLevelIsNormal()
throws PropertyVetoException
{
assertThat( cb.status(), CoreMatchers.equalTo( CircuitBreaker.Status.on ) );
// Service level goes down
cb.throwable( new IOException() );
// Service levels goes up
cb.throwable( new IllegalArgumentException() );
assertThat( cb.serviceLevel(), CoreMatchers.equalTo( 1.0 ) );
}
@Test
public void GivenCBWhenTripCBWithExceptionsAndTimeoutThenStatusIsOn()
throws PropertyVetoException
{
assertThat( cb.status(), CoreMatchers.equalTo( CircuitBreaker.Status.on ) );
// START SNIPPET: direct
// Service levels goes down and causes a trip
cb.throwable( new IOException() );
cb.throwable( new IOException() );
cb.throwable( new IOException() );
// END SNIPPET: direct
assertThat( cb.status(), CoreMatchers.equalTo( CircuitBreaker.Status.off ) );
// START SNIPPET: direct
// Wait until timeout
// END SNIPPET: direct
assertThat( cb.status(), CoreMatchers.equalTo( CircuitBreaker.Status.off ) );
System.out.println( "Wait..." );
await().atMost( FIVE_HUNDRED_MILLISECONDS ).until( circuitBreakerStatus(), is( CircuitBreaker.Status.on ) );
// START SNIPPET: direct
// CircuitBreaker is back on
// END SNIPPET: direct
assertThat( cb.status(), CoreMatchers.equalTo( CircuitBreaker.Status.on ) );
}
private Callable<CircuitBreaker.Status> circuitBreakerStatus()
{
return new Callable<CircuitBreaker.Status>()
{
@Override
public CircuitBreaker.Status call() throws Exception
{
return cb.status();
}
};
}
@Test
public void GivenCBWhenExceptionsAndSuccessesThenStatusIsOn()
throws PropertyVetoException
{
assertThat( cb.status(), CoreMatchers.equalTo( CircuitBreaker.Status.on ) );
// Service levels goes down and causes a trip
cb.throwable( new IOException() );
cb.throwable( new IOException() );
cb.success();
cb.success();
cb.throwable( new IOException() );
cb.throwable( new IOException() );
assertThat( cb.status(), CoreMatchers.equalTo( CircuitBreaker.Status.on ) );
}
@Test
public void GivenCBWhenTripCBWithExceptionsAndSuccessesThenStatusIsOff()
throws PropertyVetoException
{
assertThat( cb.status(), CoreMatchers.equalTo( CircuitBreaker.Status.on ) );
// Service levels goes down and causes a trip
cb.throwable( new IOException() );
cb.throwable( new IOException() );
cb.throwable( new IOException() );
cb.success();
assertThat( cb.status(), CoreMatchers.equalTo( CircuitBreaker.Status.off ) );
}
@Test
public void GivenCBWhenTripCBWithExceptionsAndGetStatusWithFailureThenStatusIsOff()
throws PropertyVetoException
{
assertThat( cb.status(), CoreMatchers.equalTo( CircuitBreaker.Status.on ) );
cb.addVetoableChangeListener( new VetoableChangeListener()
{
public void vetoableChange( PropertyChangeEvent evt )
throws PropertyVetoException
{
if ( evt.getNewValue() == CircuitBreaker.Status.on ) {
throw new PropertyVetoException( "Service is down", evt );
}
}
} );
// Service levels goes down and causes a trip
cb.throwable( new IOException() );
cb.throwable( new IOException() );
cb.throwable( new IOException() );
try {
System.out.println( "Wait..." );
Thread.sleep( 300 );
} catch ( InterruptedException e ) {
// Ignore
}
assertThat( cb.status(), CoreMatchers.equalTo( CircuitBreaker.Status.off ) );
assertThat( cb.lastThrowable().getMessage(), CoreMatchers.equalTo( "Service is down" ) );
}
}