Add listeners for publisher actions

src/main/java/com/amazon/opendistro/elasticsearch/performanceanalyzer/decisionmaker/actions/Action.java

@@ -33,13 +33,6 @@ public interface Action {
   /** Time to wait since last recommendation, before suggesting this action again */
   long coolOffPeriodInMillis();
 
-  /**
-   * Called when the action is invoked.
-   *
-   * <p>Specific implementation may include executing the action, or invoking downstream APIs
-   */
-  void execute();
-
   /** Returns a list of Elasticsearch nodes impacted by this action. */
   List<NodeKey> impactedNodes();
 

src/main/java/com/amazon/opendistro/elasticsearch/performanceanalyzer/decisionmaker/actions/ActionListener.java

@@ -0,0 +1,28 @@
+/*
+ * Copyright 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License").
+ * You may not use this file except in compliance with the License.
+ * A copy of the License is located at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * or in the "license" file accompanying this file. This file 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 com.amazon.opendistro.elasticsearch.performanceanalyzer.decisionmaker.actions;
+
+/**
+ * This listener is notified whenever an action suggestion is
+ * published by the decision maker Publisher
+ */
+public interface ActionListener {
+
+  /**
+   * Called when Publisher emits an action
+   */
+  void actionPublished(Action action);
+}

src/main/java/com/amazon/opendistro/elasticsearch/performanceanalyzer/decisionmaker/actions/ModifyCacheCapacityAction.java

@@ -84,13 +84,6 @@ public Map<NodeKey, ImpactVector> impact() {
         return Collections.singletonMap(esNode, impactVector);
     }
 
-    @Override
-    public void execute() {
-        // Making this a no-op for now
-        // TODO: Modify based on downstream CoS agent API calls
-        assert true;
-    }
-
     @Override
     public String summary() {
         if (!isActionable()) {

src/main/java/com/amazon/opendistro/elasticsearch/performanceanalyzer/decisionmaker/actions/ModifyQueueCapacityAction.java

@@ -81,13 +81,6 @@ public Map<NodeKey, ImpactVector> impact() {
     return Collections.singletonMap(esNode, impactVector);
   }
 
-  @Override
-  public void execute() {
-    // Making this a no-op for now
-    // TODO: Modify based on downstream agent API calls
-    assert true;
-  }
-
   @Override
   public String summary() {
     if (!isActionable()) {

src/main/java/com/amazon/opendistro/elasticsearch/performanceanalyzer/decisionmaker/deciders/Publisher.java

@@ -17,17 +17,22 @@
 
 import com.amazon.opendistro.elasticsearch.performanceanalyzer.PerformanceAnalyzerApp;
 import com.amazon.opendistro.elasticsearch.performanceanalyzer.decisionmaker.actions.Action;
+import com.amazon.opendistro.elasticsearch.performanceanalyzer.decisionmaker.actions.ActionListener;
 import com.amazon.opendistro.elasticsearch.performanceanalyzer.decisionmaker.actions.FlipFlopDetector;
 import com.amazon.opendistro.elasticsearch.performanceanalyzer.decisionmaker.actions.TimedFlipFlopDetector;
 import com.amazon.opendistro.elasticsearch.performanceanalyzer.rca.framework.core.NonLeafNode;
 import com.amazon.opendistro.elasticsearch.performanceanalyzer.rca.framework.metrics.ExceptionsAndErrors;
 import com.amazon.opendistro.elasticsearch.performanceanalyzer.rca.framework.metrics.RcaGraphMetrics;
 import com.amazon.opendistro.elasticsearch.performanceanalyzer.rca.scheduler.FlowUnitOperationArgWrapper;
 import com.google.common.annotations.VisibleForTesting;
+
 import java.time.Instant;
+import java.util.ArrayList;
 import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
 import java.util.concurrent.TimeUnit;
+
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 
@@ -40,10 +45,12 @@ public class Publisher extends NonLeafNode<EmptyFlowUnit> {
   private FlipFlopDetector flipFlopDetector;
   private boolean isMuted = false;
   private Map<String, Long> actionToExecutionTime;
+  private List<ActionListener> actionListeners;
 
   public Publisher(int evalIntervalSeconds, Collator collator) {
     super(0, evalIntervalSeconds);
     this.collator = collator;
+    this.actionListeners = new ArrayList<>();
     this.actionToExecutionTime = new HashMap<>();
     // TODO please bring in guice so we can configure this with DI
     this.flipFlopDetector = new TimedFlipFlopDetector(1, TimeUnit.HOURS);
@@ -53,8 +60,8 @@ public Publisher(int evalIntervalSeconds, Collator collator) {
   /**
    * Returns true if a given {@link Action}'s last execution time was >= {@link Action#coolOffPeriodInMillis()} ago
    *
-   * <p>If this Publisher has never executed the action, the last execution time is defined as the time that the publisher
-   * object was constructed.
+   * <p>If this Publisher has never executed the action, the last execution time is defined as the time that the
+   * publisher object was constructed.
    *
    * @param action The {@link Action} to test
    * @return true if a given {@link Action}'s last execution time was >= {@link Action#coolOffPeriodInMillis()} ago
@@ -67,7 +74,7 @@ public boolean isCooledOff(Action action) {
     } else {
       LOG.debug("Publisher: Action {} still has {} ms left in its cool off period",
           action.name(),
-              action.coolOffPeriodInMillis() - elapsed);
+          action.coolOffPeriodInMillis() - elapsed);
       return false;
     }
   }
@@ -78,10 +85,11 @@ public EmptyFlowUnit operate() {
     Decision decision = collator.getFlowUnits().get(0);
     for (Action action : decision.getActions()) {
       if (isCooledOff(action) && !flipFlopDetector.isFlipFlop(action)) {
-        LOG.info("Publisher: Executing action: [{}]", action.name());
-        action.execute();
         flipFlopDetector.recordAction(action);
         actionToExecutionTime.put(action.name(), Instant.now().toEpochMilli());
+        for (ActionListener listener : actionListeners) {
+          listener.actionPublished(action);
+        }
       }
     }
     return new EmptyFlowUnit(Instant.now().toEpochMilli());
@@ -105,6 +113,15 @@ public void generateFlowUnitListFromLocal(FlowUnitOperationArgWrapper args) {
         RcaGraphMetrics.GRAPH_NODE_OPERATE_CALL, this.name(), duration);
   }
 
+  /**
+   * Register an action listener with Publisher
+   *
+   * <p>The listener is notified whenever an action is published
+   */
+  public void addActionListener(ActionListener listener) {
+    actionListeners.add(listener);
+  }
+
   /**
    * Publisher does not have downstream nodes and does not emit flow units
    */

src/main/java/com/amazon/opendistro/elasticsearch/performanceanalyzer/plugins/Plugin.java

@@ -0,0 +1,30 @@
+/*
+ * Copyright 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License").
+ * You may not use this file except in compliance with the License.
+ * A copy of the License is located at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * or in the "license" file accompanying this file. This file 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 com.amazon.opendistro.elasticsearch.performanceanalyzer.plugins;
+
+/**
+ * Allows adding custom extensions to the analysis graph.
+ *
+ * <p>RCA framework plugins can be installed to extend the analysis graph through custom
+ * metric nodes, rca nodes, deciders or action listeners. These can subscribe to flow
+ * units from existing nodes to add new functionality, or override existing graph nodes to
+ * customize for specific use cases.
+ */
+public abstract class Plugin {
+
+  public abstract String name();
+
+}

src/main/java/com/amazon/opendistro/elasticsearch/performanceanalyzer/plugins/PluginController.java

@@ -0,0 +1,84 @@
+/*
+ * Copyright 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License").
+ * You may not use this file except in compliance with the License.
+ * A copy of the License is located at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * or in the "license" file accompanying this file. This file 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 com.amazon.opendistro.elasticsearch.performanceanalyzer.plugins;
+
+import com.amazon.opendistro.elasticsearch.performanceanalyzer.decisionmaker.actions.ActionListener;
+import com.amazon.opendistro.elasticsearch.performanceanalyzer.decisionmaker.deciders.Publisher;
+import com.google.common.annotations.VisibleForTesting;
+import java.lang.reflect.Constructor;
+import java.lang.reflect.InvocationTargetException;
+import java.util.ArrayList;
+import java.util.List;
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+
+public class PluginController {
+
+  private static final Logger LOG = LogManager.getLogger(PluginController.class);
+  private final Publisher publisher;
+  private List<Plugin> plugins;
+  private PluginControllerConfig pluginControllerConfig;
+
+  public PluginController(PluginControllerConfig pluginConfig, Publisher publisher) {
+    this.pluginControllerConfig = pluginConfig;
+    this.publisher = publisher;
+    this.plugins = new ArrayList<>();
+  }
+
+  public void initPlugins() {
+    loadFrameworkPlugins();
+    registerActionListeners();
+  }
+
+  private void loadFrameworkPlugins() {
+    for (Class<?> pluginClass : pluginControllerConfig.getFrameworkPlugins()) {
+      final Constructor<?>[] constructors = pluginClass.getConstructors();
+      if (constructors.length == 0) {
+        throw new IllegalStateException(
+            "no public constructor found for plugin class: [" + pluginClass.getName() + "]");
+      }
+      if (constructors.length > 1) {
+        throw new IllegalStateException(
+            "unique constructor expected for plugin class: [" + pluginClass.getName() + "]");
+      }
+      if (constructors[0].getParameterCount() != 0) {
+        throw new IllegalStateException(
+            "default constructor expected for plugin class: [" + pluginClass.getName() + "]");
+      }
+
+      try {
+        plugins.add((Plugin) constructors[0].newInstance());
+        LOG.info("loaded plugin: [{}]", plugins.get(plugins.size() - 1).name());
+      } catch (InstantiationException | IllegalAccessException | InvocationTargetException e) {
+        LOG.error("Failed to instantiate plugin", e);
+        throw new IllegalStateException("Failed to instantiate plugin: [" + pluginClass.getName() + "]", e);
+      }
+    }
+  }
+
+  private void registerActionListeners() {
+    for (Plugin plugin: plugins) {
+      if (ActionListener.class.isAssignableFrom(plugin.getClass())) {
+        publisher.addActionListener((ActionListener)plugin);
+      }
+    }
+  }
+
+  @VisibleForTesting
+  List<Plugin> getPlugins() {
+    return plugins;
+  }
+}

src/main/java/com/amazon/opendistro/elasticsearch/performanceanalyzer/plugins/PluginControllerConfig.java

@@ -0,0 +1,36 @@
+/*
+ * Copyright 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License").
+ * You may not use this file except in compliance with the License.
+ * A copy of the License is located at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * or in the "license" file accompanying this file. This file 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 com.amazon.opendistro.elasticsearch.performanceanalyzer.plugins;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class PluginControllerConfig {
+
+  private List<Class<? extends Plugin>> frameworkPlugins;
+
+  public PluginControllerConfig() {
+    frameworkPlugins = new ArrayList<>();
+    frameworkPlugins.add(PublisherEventsLogger.class);
+  }
+
+  /**
+   * Returns a list of entry point classes for internal framework plugins
+   */
+  public List<Class<? extends Plugin>> getFrameworkPlugins() {
+    return frameworkPlugins;
+  }
+}

src/main/java/com/amazon/opendistro/elasticsearch/performanceanalyzer/plugins/PublisherEventsLogger.java

@@ -0,0 +1,40 @@
+/*
+ * Copyright 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License").
+ * You may not use this file except in compliance with the License.
+ * A copy of the License is located at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * or in the "license" file accompanying this file. This file 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 com.amazon.opendistro.elasticsearch.performanceanalyzer.plugins;
+
+import com.amazon.opendistro.elasticsearch.performanceanalyzer.decisionmaker.actions.Action;
+import com.amazon.opendistro.elasticsearch.performanceanalyzer.decisionmaker.actions.ActionListener;
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+
+/**
+ * A simple listener that logs all actions published by the publisher
+ */
+public class PublisherEventsLogger extends Plugin implements ActionListener {
+
+  private static final Logger LOG = LogManager.getLogger(PublisherEventsLogger.class);
+  public static final String NAME = "publisher_events_logger_plugin";
+
+  @Override
+  public void actionPublished(Action action) {
+    LOG.info("Action: [{}] published by decision maker publisher.", action.name());
+  }
+
+  @Override
+  public String name() {
+    return NAME;
+  }
+}

src/main/java/com/amazon/opendistro/elasticsearch/performanceanalyzer/rca/store/ElasticSearchAnalysisGraph.java

@@ -26,6 +26,8 @@
 import com.amazon.opendistro.elasticsearch.performanceanalyzer.decisionmaker.deciders.QueueHealthDecider;
 import com.amazon.opendistro.elasticsearch.performanceanalyzer.metrics.AllMetrics.CommonDimension;
 import com.amazon.opendistro.elasticsearch.performanceanalyzer.metricsdb.MetricsDB;
+import com.amazon.opendistro.elasticsearch.performanceanalyzer.plugins.PluginController;
+import com.amazon.opendistro.elasticsearch.performanceanalyzer.plugins.PluginControllerConfig;
 import com.amazon.opendistro.elasticsearch.performanceanalyzer.rca.framework.api.AnalysisGraph;
 import com.amazon.opendistro.elasticsearch.performanceanalyzer.rca.framework.api.Metric;
 import com.amazon.opendistro.elasticsearch.performanceanalyzer.rca.framework.api.Rca;
@@ -214,6 +216,11 @@ public void construct() {
     Publisher publisher = new Publisher(EVALUATION_INTERVAL_SECONDS, collator);
     publisher.addTag(TAG_LOCUS, LOCUS_MASTER_NODE);
     publisher.addAllUpstreams(Collections.singletonList(collator));
+
+    // TODO: Refactor using DI to move out of construct method
+    PluginControllerConfig pluginControllerConfig = new PluginControllerConfig();
+    PluginController pluginController = new PluginController(pluginControllerConfig, publisher);
+    pluginController.initPlugins();
   }
 
   private void constructShardResourceUsageGraph() {