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.pc;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.util.Queue;
  import java.util.concurrent.BlockingQueue;
  import java.util.concurrent.CountDownLatch;
  import java.util.concurrent.TimeUnit;
  import java.util.concurrent.atomic.AtomicBoolean;
  import java.util.concurrent.atomic.AtomicLong;
  
  public abstract class WorkItemConsumer<T> implements Runnable {
      private static final Logger LOG = LoggerFactory.getLogger(WorkItemConsumer.class);
  
      private static final int POLLING_DURATION_SECONDS  = 5;
      private static final int DEFAULT_COMMIT_TIME_IN_MS = 15000;
  
      private final BlockingQueue<T> queue;
      private final AtomicBoolean    isDirty           = new AtomicBoolean(false);
      private final AtomicLong       maxCommitTimeInMs = new AtomicLong(DEFAULT_COMMIT_TIME_IN_MS);
      private       CountDownLatch   countdownLatch;
      private       Queue<Object>    results;
  
      public WorkItemConsumer(BlockingQueue<T> queue) {
          this.queue          = queue;
          this.countdownLatch = null;
      }
  
      public void run() {
          try {
              while (!Thread.currentThread().isInterrupted()) {
                  T item = queue.poll(POLLING_DURATION_SECONDS, TimeUnit.SECONDS);
  
                  if (item == null) {
                      LOG.debug("WorkItemConsumer.run(): no more items found in the queue. Will exit after committing");
  
                      commitDirty();
  
                      return;
                  }
  
                  isDirty.set(true);
  
                  processItem(item);
              }
          } catch (InterruptedException e) {
              LOG.error("WorkItemConsumer: Interrupted: ", e);
          } finally {
              maxCommitTimeInMs.set(0);
              countdownLatch.countDown();
          }
      }
  
      public long getMaxCommitTimeInMs() {
          long commitTime = this.maxCommitTimeInMs.get();
  
          return ((commitTime > DEFAULT_COMMIT_TIME_IN_MS) ? commitTime : DEFAULT_COMMIT_TIME_IN_MS);
      }
  
      public void setCountDownLatch(CountDownLatch countdownLatch) {
          this.countdownLatch = countdownLatch;
      }
  
      public <V> void setResults(Queue<Object> queue) {
          this.results = queue;
      }
  
      protected void commitDirty() {
          if (!isDirty.get()) {
              return;
          }
  
          LOG.info("isDirty");
          commit();
      }
  
      protected void commit() {
          long start = System.currentTimeMillis();
  
          doCommit();
  
          long end = System.currentTimeMillis();
  
          updateCommitTime((end - start));
  
          isDirty.set(false);
      }
  
      protected abstract void doCommit();
  
      protected abstract void processItem(T item);
  
      protected void addResult(Object value) {
          results.add(value);
      }
  
      protected void updateCommitTime(long commitTime) {
          if (this.maxCommitTimeInMs.get() < commitTime) {
              this.maxCommitTimeInMs.set(commitTime);
          }
      }
  }
  