/*
* Copyright (c) 2008-2013, 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.spi.annotation.
Beta;
/**
* <p>The LifecycleMapper interface is a more sophisticated version of {@link Mapper} normally used for complexer
* algorithms with a need of 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
* also the possibility given 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
*/
@
Beta
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);
}