content: /*
   * 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.ambari.server.alerts;
  
  import java.util.List;
  import java.util.Map;
  
  import org.apache.ambari.server.AmbariException;
  import org.apache.ambari.server.events.AlertEvent;
  import org.apache.ambari.server.events.AlertReceivedEvent;
  import org.apache.ambari.server.events.publishers.AlertEventPublisher;
  import org.apache.ambari.server.orm.dao.AlertDefinitionDAO;
  import org.apache.ambari.server.orm.entities.AlertDefinitionEntity;
  import org.apache.ambari.server.state.Alert;
  import org.apache.ambari.server.state.AlertState;
  import org.apache.ambari.server.state.Cluster;
  import org.apache.ambari.server.state.Clusters;
  import org.apache.ambari.server.state.alert.AlertHelper;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import com.google.inject.Inject;
  import com.google.inject.Provider;
  
  /**
   * The {@link AlertRunnable} class is used to boilerplate the expected
   * functionality of {@link Runnable}s which need to eventually create and fire
   * {@link AlertReceivedEvent}s.
   * <p/>
   * Implementations of this class do not need to concern themselves with checking
   * for whether their alert definition is enabled or with constructing and firing
   * the alert events.
   */
  public abstract class AlertRunnable implements Runnable {
  
    /**
     * Logger.
     */
    private final static Logger LOG = LoggerFactory.getLogger(AlertRunnable.class);
  
    /**
     * The alert definition name.
     */
    protected final String m_definitionName;
  
    /**
     * Used to get alert definitions to use when generating alert instances.
     */
    @Inject
    private Provider<Clusters> m_clustersProvider;
  
    /**
     * Used for looking up alert definitions.
     */
    @Inject
    private AlertDefinitionDAO m_dao;
  
    /**
     * Publishes {@link AlertEvent} instances.
     */
    @Inject
    private AlertEventPublisher m_alertEventPublisher;
  
    @Inject
    protected AlertHelper alertHelper;
  
    /**
     * Constructor.
     *
     * @param definitionName
     *          the definition name (not {@code null}).
     */
    public AlertRunnable(String definitionName) {
      m_definitionName = definitionName;
    }
  
    /**
     * Invoked on subclasses when it is time for them to check their specific
     * alert criteria. Implementations must return a list of {@link Alert}
     * instances which will be turned into {@link AlertEvent}s and published.
     * <p/>
     * This method will only be invoked if the definition is enabled for the
     * specified cluster.
     *
     * @param cluster
     *          the cluster for which the alert is executing. If there are
     *          multiple clusters defined, then this method is called once for
     *          each.
     * @param definition
     *          the information about this concrete alert.
     * @return a list of {@link Alert} to be used to create {@link AlertEvent}s
     *         and published with the {@link AlertEventPublisher} (not
     *         {@code null}).
     * @throws AmbariException
     */
    abstract List<Alert> execute(Cluster cluster, AlertDefinitionEntity definition)
        throws AmbariException;
  
    /**
     * {@inheritDoc}
     */
    @Override
    public final void run() {
      try {
        Map<String, Cluster> clusterMap = m_clustersProvider.get().getClusters();
        for (Cluster cluster : clusterMap.values()) {
          AlertDefinitionEntity definition = m_dao.findByName(cluster.getClusterId(), m_definitionName);
  
          // skip this cluster if the runnable's alert definition is missing or
          // disabled
          if (null == definition || !definition.getEnabled()) {
            continue;
          }
  
          // for every alert generated from the implementation, fire an event
          List<Alert> alerts = execute(cluster, definition);
          for (Alert alert : alerts) {
            AlertReceivedEvent event = new AlertReceivedEvent(cluster.getClusterId(), alert);
            m_alertEventPublisher.publish(event);
          }
        }
      } catch (Exception exception) {
        LOG.error("Unable to run the {} alert", m_definitionName, exception);
      }
    }
  
    /**
     * Builds an {@link Alert} instance.
     *
     * @param cluster
     *          the cluster the alert is for (not {@code null}).
     * @param myDefinition
     *          the alert's definition (not {@code null}).
     * @param alertState
     *          the state of the alert (not {@code null}).
     * @param message
     *          the alert text.
     * @return and alert.
     */
    protected Alert buildAlert(Cluster cluster, AlertDefinitionEntity myDefinition,
        AlertState alertState, String message) {
      Alert alert = new Alert(myDefinition.getDefinitionName(), null, myDefinition.getServiceName(),
          myDefinition.getComponentName(), null, alertState);
  
      alert.setLabel(myDefinition.getLabel());
      alert.setText(message);
      alert.setTimestamp(System.currentTimeMillis());
      alert.setClusterId(cluster.getClusterId());
  
      return alert;
    }
  }
  