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From aledsage <...@git.apache.org>
Subject [GitHub] brooklyn-server pull request #832: Add ManagementNodeStateListener support
Date Tue, 19 Sep 2017 20:04:25 GMT
Github user aledsage commented on a diff in the pull request:

    https://github.com/apache/brooklyn-server/pull/832#discussion_r139803014
  
    --- Diff: core/src/main/java/org/apache/brooklyn/core/mgmt/internal/ManagementNodeStateListenerManager.java
---
    @@ -0,0 +1,175 @@
    +/*
    + * 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.brooklyn.core.mgmt.internal;
    +
    +import static com.google.common.base.Preconditions.checkNotNull;
    +
    +import java.io.Closeable;
    +import java.io.IOException;
    +import java.util.Collection;
    +import java.util.List;
    +import java.util.concurrent.Executors;
    +import java.util.concurrent.TimeUnit;
    +import java.util.concurrent.atomic.AtomicInteger;
    +
    +import org.apache.brooklyn.api.mgmt.ha.ManagementNodeState;
    +import org.apache.brooklyn.core.mgmt.ManagementContextInjectable;
    +import org.apache.brooklyn.core.mgmt.usage.ManagementNodeStateListener;
    +import org.apache.brooklyn.core.server.BrooklynServerConfig;
    +import org.apache.brooklyn.util.core.ClassLoaderUtils;
    +import org.apache.brooklyn.util.core.flags.TypeCoercions;
    +import org.apache.brooklyn.util.exceptions.Exceptions;
    +import org.apache.brooklyn.util.time.Duration;
    +import org.slf4j.Logger;
    +import org.slf4j.LoggerFactory;
    +
    +import com.google.common.base.Function;
    +import com.google.common.collect.Lists;
    +import com.google.common.util.concurrent.Futures;
    +import com.google.common.util.concurrent.ListenableFuture;
    +import com.google.common.util.concurrent.ListeningExecutorService;
    +import com.google.common.util.concurrent.MoreExecutors;
    +import com.google.common.util.concurrent.ThreadFactoryBuilder;
    +
    +/**
    + * Handles the notification of {@link ManagementNodeStateListener}s.
    + * 
    + * @see {@link BrooklynServerConfig#MANAGEMENT_NODE_STATE_LISTENERS} for configuring
this.
    + * @see {@link org.apache.brooklyn.core.mgmt.ha.HighAvailabilityManagerImpl#HighAvailabilityManagerImpl(ManagementContextInternal,
ManagementNodeStateListener)}
    + *      for how we get notified of the state-change.
    + */
    +public class ManagementNodeStateListenerManager implements ManagementNodeStateListener
{
    +
    +    private static final Logger LOG = LoggerFactory.getLogger(ManagementNodeStateListenerManager.class);
    +
    +    private final ManagementContextInternal mgmt;
    +    
    +    private final Object mutex = new Object();
    +
    +    private final List<ManagementNodeStateListener> listeners = Lists.newCopyOnWriteArrayList();
    +    private ManagementNodeState lastPublishedVal;
    +    
    +    private final AtomicInteger listenerQueueSize = new AtomicInteger();
    +    
    +    private ListeningExecutorService listenerExecutor = MoreExecutors.listeningDecorator(Executors.newSingleThreadExecutor(new
ThreadFactoryBuilder()
    +            .setNameFormat("brooklyn-managementnodestate-listener-%d")
    +            .build()));
    +
    +    public ManagementNodeStateListenerManager(ManagementContextInternal managementContext)
{
    +        this.mgmt = checkNotNull(managementContext, "managementContext");
    +        
    +        // Register a coercion from String->ManagementNodeStateListener, so that MANAGEMENT_NODE_STATE_LISTENERS
defined in brooklyn.cfg
    +        // will be instantiated, given their class names.
    +        TypeCoercions.BrooklynCommonAdaptorTypeCoercions.registerInstanceForClassnameAdapter(
    +                new ClassLoaderUtils(this.getClass(), managementContext), 
    +                ManagementNodeStateListener.class);
    +
    +        // Although changing listeners to Collection<ManagementNodeStateListener>
is valid at compile time
    +        // the collection will contain any objects that could not be coerced by the function
    +        // declared above. Generally this means any string declared in brooklyn.properties
    +        // that is not a ManagementNodeStateListener.
    +        Collection<?> rawListeners = managementContext.getBrooklynProperties().getConfig(BrooklynServerConfig.MANAGEMENT_NODE_STATE_LISTENERS);
    +        if (rawListeners != null) {
    +            for (Object obj : rawListeners) {
    +                if (obj == null) {
    +                    throw new NullPointerException("null listener in config " + BrooklynServerConfig.MANAGEMENT_NODE_STATE_LISTENERS);
    +                } else if (!(obj instanceof ManagementNodeStateListener)) {
    +                    throw new ClassCastException("Configured object is not a "+ManagementNodeStateListener.class.getSimpleName()+".
This probably means coercion failed: " + obj);
    +                } else {
    +                    ManagementNodeStateListener listener = (ManagementNodeStateListener)
obj;
    +                    if (listener instanceof ManagementContextInjectable) {
    +                        ((ManagementContextInjectable) listener).setManagementContext(managementContext);
    +                    }
    +                    listeners.add((ManagementNodeStateListener)listener);
    +                }
    +            }
    +        }
    +    }
    +
    +    @Override
    +    public void onStateChange(ManagementNodeState state) {
    --- End diff --
    
    Agreed it's a bit strange. But I didn't want to complicate the `HighAvailabilityManagerImpl`
more. It would only be a few lines in there (a new field to store the last value, etc) - I
could move it there if you think it's better @Graeme-Miller?


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