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Add new service cache listener to let users know what instances have … #265

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50 changes: 50 additions & 0 deletions ...overy/src/main/java/org/apache/curator/x/discovery/details/ServiceCacheEventListener.java
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Original file line number Diff line number Diff line change
@@ -0,0 +1,50 @@
/**
* 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.curator.x.discovery.details;

import org.apache.curator.x.discovery.ServiceInstance;

/**
* Listener for events (addition/update/deletion) that happen to a service cache
*/
public interface ServiceCacheEventListener<T> extends ServiceCacheListener
{

/**
* Called when a new cache is added.
*
* @param added instance added
*/
public void cacheAdded(ServiceInstance<T> added);

/**
* Called when a cache is deleted.
*
* @param deleted instance deleted
*/
public void cacheDeleted(ServiceInstance<T> deleted);

/**
* Called when a cache is updated.
*
* @param old old instance
* @param updated updated instance
*/
public void cacheUpdated(ServiceInstance<T> old, ServiceInstance<T> updated);
}
109 changes: 77 additions & 32 deletions ...or-x-discovery/src/main/java/org/apache/curator/x/discovery/details/ServiceCacheImpl.java
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Original file line number Diff line number Diff line change
Expand Up @@ -93,7 +93,7 @@ public void start() throws Exception
cache.start(true);
for ( ChildData childData : cache.getCurrentData() )
{
addInstance(childData, true);
addInstanceOnlyIfAbsent(childData);
}
discovery.cacheOpened(this);
}
Expand Down Expand Up @@ -146,59 +146,104 @@ public void removeListener(ServiceCacheListener listener)
@Override
public void childEvent(CuratorFramework client, PathChildrenCacheEvent event) throws Exception
{
boolean notifyListeners = false;
switch ( event.getType() )
final Tuple<T> tuple;
switch ( event.getType() )
{
case CHILD_ADDED:
tuple = addOrUpdateInstance(event.getData());
listenerContainer.forEach(
new Function<ServiceCacheListener, Void>()
{
@Override
public Void apply(ServiceCacheListener listener)
{
listener.cacheChanged();

if(listener instanceof ServiceCacheEventListener) {
((ServiceCacheEventListener) listener).cacheAdded(tuple.newInstance);
}

return null;
}
}
);
break;
case CHILD_UPDATED:
{
addInstance(event.getData(), false);
notifyListeners = true;
tuple = addOrUpdateInstance(event.getData());
listenerContainer.forEach(
new Function<ServiceCacheListener, Void>()
{
@Override
public Void apply(ServiceCacheListener listener)
{
listener.cacheChanged();

if(listener instanceof ServiceCacheEventListener) {
((ServiceCacheEventListener) listener).cacheUpdated(tuple.oldInstance, tuple.newInstance);
}

return null;
}
}
);
break;
}

case CHILD_REMOVED:
{
instances.remove(instanceIdFromData(event.getData()));
notifyListeners = true;
final ServiceInstance<T> serviceInstance = instances.remove(instanceIdFromData(event.getData()));
listenerContainer.forEach(
new Function<ServiceCacheListener, Void>()
{
@Override
public Void apply(ServiceCacheListener listener)
{
listener.cacheChanged();

if(listener instanceof ServiceCacheEventListener) {
((ServiceCacheEventListener) listener).cacheDeleted(serviceInstance);
}

return null;
}
}
);
break;
}
}

if ( notifyListeners )
{
listenerContainer.forEach
(
new Function<ServiceCacheListener, Void>()
{
@Override
public Void apply(ServiceCacheListener listener)
{
listener.cacheChanged();
return null;
}
}
);
}
}

private String instanceIdFromData(ChildData childData)
{
return ZKPaths.getNodeFromPath(childData.getPath());
}

private void addInstance(ChildData childData, boolean onlyIfAbsent) throws Exception
private void addInstanceOnlyIfAbsent(ChildData childData) throws Exception
{
String instanceId = instanceIdFromData(childData);
ServiceInstance<T> serviceInstance = discovery.getSerializer().deserialize(childData.getData());
if ( onlyIfAbsent )
{
instances.putIfAbsent(instanceId, serviceInstance);
}
else
{
instances.put(instanceId, serviceInstance);
}

instances.putIfAbsent(instanceId, serviceInstance);
cache.clearDataBytes(childData.getPath(), childData.getStat().getVersion());
}

private Tuple<T> addOrUpdateInstance(ChildData childData) throws Exception
{
String instanceId = instanceIdFromData(childData);
ServiceInstance<T> serviceInstance = discovery.getSerializer().deserialize(childData.getData());
final Tuple<T> result = new Tuple<>(instances.put(instanceId, serviceInstance), serviceInstance);
cache.clearDataBytes(childData.getPath(), childData.getStat().getVersion());
return result;
}

private static class Tuple<T> {
public final ServiceInstance<T> oldInstance;
public final ServiceInstance<T> newInstance;

private Tuple(final ServiceInstance<T> oldInstance, final ServiceInstance<T> newInstance) {
this.oldInstance = oldInstance;
this.newInstance = newInstance;
}
}
}
80 changes: 80 additions & 0 deletions curator-x-discovery/src/test/java/org/apache/curator/x/discovery/TestServiceCache.java
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Expand Up @@ -28,6 +28,7 @@
import org.apache.curator.test.ExecuteCalledWatchingExecutorService;
import org.apache.curator.test.Timing;
import org.apache.curator.utils.CloseableUtils;
import org.apache.curator.x.discovery.details.ServiceCacheEventListener;
import org.apache.curator.x.discovery.details.ServiceCacheListener;
import org.testng.Assert;
import org.testng.annotations.Test;
Expand All @@ -39,6 +40,7 @@
import java.util.concurrent.Executors;
import java.util.concurrent.Semaphore;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicBoolean;

public class TestServiceCache extends BaseClassForTests
{
Expand Down Expand Up @@ -310,4 +312,82 @@ public void stateChanged(CuratorFramework client, ConnectionState newState)
}
}
}

@Test
public void testServiceCacheEventListener() throws Exception
{
List<Closeable> closeables = Lists.newArrayList();
try
{
CuratorFramework client = CuratorFrameworkFactory.newClient(server.getConnectString(), new RetryOneTime(1));
closeables.add(client);
client.start();

ServiceDiscovery<String> discovery = ServiceDiscoveryBuilder.builder(String.class).basePath("/discovery").client(client).build();
closeables.add(discovery);
discovery.start();

ServiceCache<String> cache = discovery.serviceCacheBuilder().name("test").build();
closeables.add(cache);

final CountDownLatch latch = new CountDownLatch(6);

final AtomicBoolean notifyError = new AtomicBoolean(false);
ServiceCacheListener listener = new ServiceCacheEventListener<String>()
{
@Override
public void cacheAdded(final ServiceInstance<String> added) {
latch.countDown();

notifyError.compareAndSet(false,added == null);
}

@Override
public void cacheDeleted(final ServiceInstance<String> deleted) {
latch.countDown();

notifyError.compareAndSet(false,deleted == null);
}

@Override
public void cacheUpdated(final ServiceInstance<String> before, final ServiceInstance<String> after) {
latch.countDown();

notifyError.compareAndSet(false, !"before".equals(before.getPayload()));
notifyError.compareAndSet(false, !"after".equals(after.getPayload()));
}

@Override
public void cacheChanged()
{
latch.countDown();
}

@Override
public void stateChanged(CuratorFramework client, ConnectionState newState)
{

}
};
cache.addListener(listener);
cache.start();

ServiceInstance<String> instance = ServiceInstance.<String>builder().payload("before").name("test").port(10064).build();
discovery.registerService(instance);
instance = ServiceInstance.<String>builder().id(instance.getId()).payload("after").name("test").port(10064).build();
discovery.updateService(instance);
discovery.unregisterService(instance);
Assert.assertTrue(latch.await(10, TimeUnit.SECONDS));

Assert.assertFalse(notifyError.get());
}
finally
{
Collections.reverse(closeables);
for ( Closeable c : closeables )
{
CloseableUtils.closeQuietly(c);
}
}
}
}