/*

  * 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.block_app.framework.api.local;

 import java.util.Map;

 import java.util.Map.Entry;

 import org.apache.giraph.master.MasterGlobalCommUsage;

 import org.apache.giraph.reducers.ReduceOperation;

 import org.apache.giraph.reducers.Reducer;

 import org.apache.giraph.utils.WritableUtils;

 import org.apache.giraph.worker.WorkerGlobalCommUsage;

 import org.apache.hadoop.io.Writable;

 import com.google.common.collect.Maps;

 /**

  * Internal aggregators implementation

  */

 @SuppressWarnings("unchecked")

 class InternalAggregators

     implements MasterGlobalCommUsage, WorkerGlobalCommUsage {

   private final boolean runAllChecks;

   /** Map of reducers registered for the next worker computation */

   private final Map<String, Reducer<Object, Writable>> reducerMap =

       Maps.newHashMap();

   /** Map of values to be sent to workers for next computation */

   private final Map<String, Writable> broadcastMap =

       Maps.newHashMap();

   /** Values reduced from previous computation */

   private final Map<String, Writable> reducedMap =

       Maps.newHashMap();

   public InternalAggregators(boolean runAllChecks) {

     this.runAllChecks = runAllChecks;

   }

   private static <T> T getOrThrow(

       Map<String, T> map, String mapName, String key) {

     T value = map.get(key);

     if (value == null) {

       throw new IllegalArgumentException(

           key + " not present in " + mapName);

     }

     return value;

   }

   @Override

   public void broadcast(String name, Writable value) {

     broadcastMap.put(name, value);

   }

   @Override

   public <B extends Writable> B getBroadcast(String name) {

     return (B) getOrThrow(broadcastMap, "broadcastMap", name);

   }

   @Override

   public <S, R extends Writable> void registerReducer(

       String name, ReduceOperation<S, R> reduceOp) {

     registerReducer(name, reduceOp, reduceOp.createInitialValue());

   }

   @Override

   public <S, R extends Writable> void registerReducer(

       String name, ReduceOperation<S, R> reduceOp,

       R globalInitialValue) {

     if (reducerMap.containsKey(name)) {

       throw new IllegalArgumentException(

           "Reducer with name " + name + " was already registered, " +

           " and is " + reducerMap.get(name).getReduceOp() +

           ", and we are trying to " + " register " + reduceOp);

     }

     if (reduceOp == null) {

       throw new IllegalArgumentException(

           "null reducer cannot be registered, with name " + name);

     }

     if (globalInitialValue == null) {

       throw new IllegalArgumentException(

           "global initial value for reducer cannot be null, but is for " +

           reduceOp + " with naem" + name);

     }

     Reducer<S, R> reducer = new Reducer<>(reduceOp, globalInitialValue);

     reducerMap.put(name, (Reducer<Object, Writable>) reducer);

   }

   @Override

   public void reduce(String name, Object value) {

     Reducer<Object, Writable> reducer =

         getOrThrow(reducerMap, "reducerMap", name);

     synchronized (reducer) {

       reducer.reduce(value);

     }

   }

   @Override

   public void reduceMerge(String name, Writable value) {

     Reducer<Object, Writable> reducer =

         getOrThrow(reducerMap, "reducerMap", name);

     synchronized (reducer) {

       reducer.reduceMerge(value);

     }

   }

   @Override

   public <R extends Writable> R getReduced(String name) {

     return (R) getOrThrow(reducedMap, "reducedMap", name);

   }

   public synchronized void afterWorkerBeforeMaster() {

     broadcastMap.clear();

     reducedMap.clear();

     for (Entry<String, Reducer<Object, Writable>> entry :

           reducerMap.entrySet()) {

       Writable value = entry.getValue().getCurrentValue();

       if (runAllChecks) {

         Writable newValue = entry.getValue().createInitialValue();

         WritableUtils.copyInto(value, newValue);

         value = newValue;

       }

       reducedMap.put(entry.getKey(), value);

     }

     reducerMap.clear();

   }

 }