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.utils;
  
  import java.util.Collections;
  import java.util.HashSet;
  import java.util.Set;
  import java.util.concurrent.Callable;
  
  import org.apache.ambari.server.AmbariException;
  import org.apache.ambari.server.state.Cluster;
  import org.apache.ambari.server.state.Clusters;
  import org.eclipse.persistence.exceptions.DatabaseException;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * Provides utility methods to support operations retry
   * TODO injection as Guice singleon, static for now to avoid major modifications
   */
  public class RetryHelper {
    private static final Logger LOG = LoggerFactory.getLogger(RetryHelper.class);
    private static Clusters s_clusters;
  
    private static ThreadLocal<Set<Cluster>> affectedClusters = new ThreadLocal<Set<Cluster>>(){
      @Override
      protected Set<Cluster> initialValue() {
        return new HashSet<>();
      }
    };
  
    private static int operationsRetryAttempts = 0;
  
    public static void init(Clusters clusters, int operationsRetryAttempts) {
      s_clusters = clusters;
      RetryHelper.operationsRetryAttempts = operationsRetryAttempts;
    }
  
    public static void addAffectedCluster(Cluster cluster) {
      if (operationsRetryAttempts > 0 ) {
        affectedClusters.get().add(cluster);
      }
    }
  
    public static Set<Cluster> getAffectedClusters() {
      return Collections.unmodifiableSet(affectedClusters.get());
    }
  
    public static void clearAffectedClusters() {
      if (operationsRetryAttempts > 0) {
        affectedClusters.get().clear();
      }
    }
  
    public static int getOperationsRetryAttempts() {
      return operationsRetryAttempts;
    }
  
    public static boolean isDatabaseException(Throwable ex) {
      do {
        if (ex instanceof DatabaseException) {
          return true;
        }
        ex = ex.getCause();
  
      } while (ex != null);
  
      return false;
    }
  
    public static void invalidateAffectedClusters() {
      for (Cluster cluster : affectedClusters.get()) {
        s_clusters.invalidate(cluster);
        affectedClusters.get().remove(cluster);
      }
    }
  
    public static <T> T executeWithRetry(Callable<T> command) throws AmbariException {
      RetryHelper.clearAffectedClusters();
      int retryAttempts = RetryHelper.getOperationsRetryAttempts();
      do {
        try {
          return command.call();
        } catch (Exception e) {
          if (RetryHelper.isDatabaseException(e)) {
  
            RetryHelper.invalidateAffectedClusters();
  
            if (retryAttempts > 0) {
              LOG.error("Ignoring database exception to perform operation retry, attempts remaining: " + retryAttempts, e);
              retryAttempts--;
            } else {
              RetryHelper.clearAffectedClusters();
              throw new AmbariException(e.getMessage(), e);
            }
          } else {
            RetryHelper.clearAffectedClusters();
            throw new AmbariException(e.getMessage(), e);
          }
        }
  
      } while (true);
    }
  }
  