/*

  * 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.giraph.utils;

 import java.util.ArrayList;

 import java.util.List;

 /**

  * Makes a list of {@link ProgressCounter} accessible through

  * a {@link ThreadLocal}.

  */

 public class ThreadLocalProgressCounter extends ThreadLocal<ProgressCounter> {

   /**

    * List of counters.

    */

   private final List<ProgressCounter> counters = new ArrayList<>();

   /**

    * Initializes a new counter, adds it to the list of counters

    * and returns it.

    * @return Progress counter.

    */

   @Override

   protected ProgressCounter initialValue() {

     ProgressCounter threadCounter = new ProgressCounter();

     synchronized (counters) {

       counters.add(threadCounter);

     }

     return threadCounter;

   }

   /**

    * Sums the progress of all counters.

    * @return Sum of all counters

    */

   public long getProgress() {

     long progress = 0;

     synchronized (counters) {

       for (ProgressCounter entry : counters) {

         progress += entry.getValue();

       }

     }

     return progress;

   }

   /**

    * Removes all counters.

    */

   public void reset() {

     counters.clear();

   }

 }