/*
 * Copyright (c) 2008-2017, Hazelcast, Inc. All Rights Reserved.
 *
 * Licensed 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 com.hazelcast.mapreduce;

import com.hazelcast.nio.serialization.BinaryInterface;

/**
 * <p>The LifecycleMapper interface is a more sophisticated version of {@link Mapper} normally used for more complex
 * algorithms with a need for initialization and finalization.</p>
 * <p>The behavior is the same as for {@link Mapper}, but {@link #initialize(Context)} is called before calling
 * {@link #map(Object, Object, Context)} for the first time to prepare the mapper instance and maybe already
 * emit some values. After all mapping calls are finished, {@link #finalized(Context)} is called and here is
 * another possibility to emit additional key-value pairs.</p>
 *
 * @param <KeyIn>    type of key used in the {@link KeyValueSource}
 * @param <ValueIn>  type of value used in the {@link KeyValueSource}
 * @param <KeyOut>   key type for mapped results
 * @param <ValueOut> value type for mapped results
 * @since 3.2
 * @deprecated MapReduce is deprecated and will be removed in 4.0.
 * For map aggregations, you can use {@link com.hazelcast.aggregation.Aggregator} on IMap.
 * For general data processing, it is superseded by <a href="http://jet.hazelcast.org">Hazelcast Jet</a>.
 */
@Deprecated
@BinaryInterface
public interface LifecycleMapper<KeyIn, ValueIn, KeyOut, ValueOut>
        extends Mapper<KeyIn, ValueIn, KeyOut, ValueOut> {

    /**
     * This method is called before the {@link #map(Object, Object, Context)} method is executed for every value and
     * can be used to initialize the internal state of the mapper or to emit a special value.
     *
     * @param context Context to be used for emitting values
     */
    void initialize(Context<KeyOut, ValueOut> context);

    /**
     * This method is called after the {@link #map(Object, Object, Context)} method is executed for every value and
     * can be used to finalize the internal state of the mapper or to emit a special value.
     *
     * @param context Context to be used for emitting values
     */
    void finalized(Context<KeyOut, ValueOut> context);

}