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.impala.hook;
  
  import org.apache.atlas.plugin.classloader.AtlasPluginClassLoader;
  import org.apache.impala.hooks.QueryCompleteContext;
  import org.apache.impala.hooks.QueryEventHook;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * This class is used to convert lineage records from Impala to lineage notifications and
   * send them to Atlas.
   */
  public class ImpalaLineageHook implements QueryEventHook {
      private static final Logger LOG = LoggerFactory.getLogger(ImpalaLineageHook.class);
  
      private static final String ATLAS_PLUGIN_TYPE_IMPALA = "impala";
      private static final String ATLAS_IMPALA_LINEAGE_HOOK_IMPL_CLASSNAME =
              "org.apache.atlas.impala.hook.ImpalaHook";
  
      private AtlasPluginClassLoader atlasPluginClassLoader;
      private QueryEventHook impalaLineageHookImpl;
  
      public ImpalaLineageHook() {
      }
  
      /**
       * Execute Impala hook
       */
      public void onQueryComplete(QueryCompleteContext context) {
          LOG.debug("==> ImpalaLineageHook.onQueryComplete()");
  
          try {
              activatePluginClassLoader();
              impalaLineageHookImpl.onQueryComplete(context);
          } catch (Exception ex) {
              String errorMessage = String.format("Error in processing impala lineage: {}", context.getLineageGraph());
              LOG.error(errorMessage, ex);
          } finally {
              deactivatePluginClassLoader();
          }
  
          LOG.debug("<== ImpalaLineageHook.onQueryComplete()");
      }
  
      /**
       * Initialization of Impala hook
       */
      public void onImpalaStartup() {
          LOG.debug("==> ImpalaLineageHook.onImpalaStartup()");
  
          try {
              atlasPluginClassLoader = AtlasPluginClassLoader.getInstance(ATLAS_PLUGIN_TYPE_IMPALA, this.getClass());
  
              @SuppressWarnings("unchecked")
              Class<QueryEventHook> cls = (Class<QueryEventHook>) Class
                      .forName(ATLAS_IMPALA_LINEAGE_HOOK_IMPL_CLASSNAME, true, atlasPluginClassLoader);
  
              activatePluginClassLoader();
  
              impalaLineageHookImpl = cls.newInstance();
              impalaLineageHookImpl.onImpalaStartup();
          } catch (Exception excp) {
              LOG.error("Error instantiating Atlas hook implementation for Impala lineage", excp);
          } finally {
              deactivatePluginClassLoader();
          }
  
          LOG.debug("<== ImpalaLineageHook.onImpalaStartup()");
      }
  
      private void activatePluginClassLoader() {
          if (atlasPluginClassLoader != null) {
              atlasPluginClassLoader.activate();
          }
      }
  
      private void deactivatePluginClassLoader() {
          if (atlasPluginClassLoader != null) {
              atlasPluginClassLoader.deactivate();
          }
      }
  }
  