/*

  * 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.metrics;

 import org.apache.giraph.conf.GiraphConfiguration;

 import org.apache.giraph.utils.GcTracker;

 import com.google.common.collect.Lists;

 import java.io.PrintStream;

 import java.util.List;

 import static org.apache.giraph.bsp.BspService.INPUT_SUPERSTEP;

 /**

  * Top level metrics class for using Yammer's metrics in Giraph.

  */

 public class GiraphMetrics {

   /** Singleton instance for everyone to use */

   private static GiraphMetrics INSTANCE = new GiraphMetrics();

   /** registry for per-superstep metrics */

   private final SuperstepMetricsRegistry perSuperstep;

   /** registry for optional per-job metrics */

   private final GiraphMetricsRegistry perJobOptional;

   /** registry for required per-job metrics */

   private final GiraphMetricsRegistry perJobRequired;

   /** Garbage collection tracker */

   private final GcTracker gcTracker;

   /** observer for per-superstep metrics re-initialization */

   private final List<ResetSuperstepMetricsObserver> observers =

       Lists.newArrayList();

   /**

    * Initialize no-op registry that creates no-op metrics.

    */

   private GiraphMetrics() {

     perJobOptional = GiraphMetricsRegistry.createFake();

     perSuperstep = SuperstepMetricsRegistry.createFake();

     perJobRequired = GiraphMetricsRegistry.createWithOptional("giraph", "job");

     gcTracker = new GcTracker();

   }

   /**

    * Initialize GiraphMetrics with Hadoop Context

    *

    * @param conf GiraphConfiguration to use.

    */

   private GiraphMetrics(GiraphConfiguration conf) {

     perJobOptional = GiraphMetricsRegistry.create(conf, "giraph", "job");

     perSuperstep = SuperstepMetricsRegistry.create(conf, INPUT_SUPERSTEP);

     perJobRequired = GiraphMetricsRegistry.createWithOptional("giraph", "job");

     gcTracker = new GcTracker(conf);

   }

   /**

    * Get singleton instance of GiraphMetrics.

    *

    * @return GiraphMetrics singleton instance

    */

   public static GiraphMetrics get() {

     return INSTANCE;

   }

   /**

    * Initialize singleton instance of GiraphMetrics.

    *

    * @param conf GiraphConfiguration to use.

    */

   public static void init(GiraphConfiguration conf) {

     INSTANCE = new GiraphMetrics(conf);

   }

   /**

    * Get per-job optional metrics.

    *

    * @return per-job optional {@link GiraphMetricsRegistry}

    */

   public GiraphMetricsRegistry perJobOptional() {

     return perJobOptional;

   }

   /**

    * Get per-job required metrics.

    *

    * @return per-job require {@link GiraphMetricsRegistry}

    */

   public GiraphMetricsRegistry perJobRequired() {

     return perJobRequired;

   }

   /**

    * Get per-superstep metrics.

    *

    * @return per-superstep GiraphMetricsRegistry

    */

   public SuperstepMetricsRegistry perSuperstep() {

     return perSuperstep;

   }

   /**

    * Get GC tracker

    *

    * @return Gc tracker

    */

   public GcTracker getGcTracker() {

     return gcTracker;

   }

   /**

    * Anyone using per-superstep counters needs to re-initialize their Metrics

    * object on each new superstep. Otherwise they will always be updating just

    * one counter. This method allows people to easily register a callback for

    * when they should do the re-initializing.

    *

    * @param observer SuperstepObserver to watch

    */

   public synchronized void addSuperstepResetObserver(

       ResetSuperstepMetricsObserver observer) {

     observers.add(observer);

   }

   /**

    * Reset the per-superstep MetricsRegistry

    *

    * @param superstep long number of superstep

    */

   public synchronized void resetSuperstepMetrics(long superstep) {

     perSuperstep.setSuperstep(superstep);

     for (ResetSuperstepMetricsObserver observer : observers) {

       observer.newSuperstep(perSuperstep);

     }

   }

   /**

    * Dump all metrics to output stream provided.

    *

    * @param out PrintStream to dump to.

    */

   public void dumpToStream(PrintStream out) {

     perJobOptional.printToStream(out);

     perJobRequired.printToStream(out);

   }

   /**

    * Stop using metrics (for cleanup)

    */

   public void shutdown() {

     perJobOptional.shutdown();

     perJobRequired.shutdown();

     perSuperstep.shutdown();

   }

 }