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
   * <p>
   * http://www.apache.org/licenses/LICENSE-2.0
   * <p>
   * 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.atlas.notification;
  
  import org.apache.atlas.GraphTransactionInterceptor;
  import org.apache.commons.collections.CollectionUtils;
  import org.apache.commons.configuration.Configuration;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.util.ArrayList;
  import java.util.List;
  
  import static org.apache.atlas.notification.NotificationInterface.NotificationType.ENTITIES;
  
  public class EntityNotificationSender<T> {
      private static final Logger LOG = LoggerFactory.getLogger(EntityNotificationSender.class);
  
      private static final boolean NOTIFY_POST_COMMIT_DEFAULT = true;
  
      private final NotificationSender<T> notificationSender;
  
      public EntityNotificationSender(NotificationInterface notificationInterface, Configuration configuration) {
          this(notificationInterface, configuration != null ? configuration.getBoolean("atlas.notification.send.postcommit", NOTIFY_POST_COMMIT_DEFAULT) : NOTIFY_POST_COMMIT_DEFAULT);
      }
  
      public EntityNotificationSender(NotificationInterface notificationInterface, boolean sendPostCommit) {
          if (sendPostCommit) {
              LOG.info("EntityNotificationSender: notifications will be sent after transaction commit");
  
              this.notificationSender = new PostCommitNotificationSender<>(notificationInterface);
          } else {
              LOG.info("EntityNotificationSender: notifications will be sent inline (i.e. not waiting for transaction to commit)");
  
              this.notificationSender = new InlineNotificationSender<>(notificationInterface);
          }
      }
  
      public void send(List<T> notifications) throws NotificationException {
          this.notificationSender.send(notifications);
      }
  
      private interface NotificationSender<T> {
          void send(List<T> notifications) throws NotificationException;
      }
  
      private static class InlineNotificationSender<T> implements NotificationSender<T> {
          private final NotificationInterface notificationInterface;
  
          public InlineNotificationSender(NotificationInterface notificationInterface) {
              this.notificationInterface = notificationInterface;
          }
  
          @Override
          public void send(List<T> notifications) throws NotificationException {
              notificationInterface.send(ENTITIES, notifications);
          }
      }
  
      private static class PostCommitNotificationSender<T> implements NotificationSender<T> {
          private final NotificationInterface                      notificationInterface;
          private final ThreadLocal<PostCommitNotificationHook<T>> postCommitNotificationHooks = new ThreadLocal<>();
  
          public PostCommitNotificationSender(NotificationInterface notificationInterface) {
              this.notificationInterface = notificationInterface;
          }
  
          @Override
          public void send(List<T> notifications) {
              PostCommitNotificationHook<T> notificationHook = postCommitNotificationHooks.get();
  
              if (notificationHook == null) {
                  notificationHook = new PostCommitNotificationHook<>(notifications);
  
                  postCommitNotificationHooks.set(notificationHook);
              } else {
                  notificationHook.addNotifications(notifications);
              }
          }
  
          class PostCommitNotificationHook<U> extends GraphTransactionInterceptor.PostTransactionHook {
              private final List<U> notifications = new ArrayList<>();
  
              public PostCommitNotificationHook(List<U> notifications) {
                  this.addNotifications(notifications);
              }
  
              public void addNotifications(List<U> notifications) {
                  if (notifications != null) {
                      this.notifications.addAll(notifications);
                  }
              }
  
              @Override
              public void onComplete(boolean isSuccess) {
                  postCommitNotificationHooks.remove();
  
                  if (CollectionUtils.isNotEmpty(notifications)) {
                      if (isSuccess) {
                          try {
                              notificationInterface.send(ENTITIES, notifications);
                          } catch (NotificationException excp) {
                              LOG.error("failed to send entity notifications", excp);
                          }
                      } else {
                          if (LOG.isDebugEnabled()) {
                              LOG.debug("Transaction not committed. Not sending {} notifications: {}", notifications.size(), notifications);
                          }
                      }
                  }
              }
          }
      }
  }
  