/**
* 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.hcatalog.data.transfer;
import java.util.Map;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.mapreduce.InputSplit;
import org.apache.hcatalog.data.transfer.impl.HCatInputFormatReader;
import org.apache.hcatalog.data.transfer.impl.HCatOutputFormatWriter;
import org.apache.hcatalog.data.transfer.state.DefaultStateProvider;
import org.apache.hcatalog.data.transfer.state.StateProvider;
/**
* Use this factory to get instances of {@link HCatReader} or {@link HCatWriter}
* at master and slave nodes.
*/
public class DataTransferFactory {
/**
* This should be called once from master node to obtain an instance of
* {@link HCatReader}.
*
* @param re
* ReadEntity built using {@link ReadEntity.Builder}
* @param config
* any configuration which master node wants to pass to HCatalog
* @return {@link HCatReader}
*/
public static HCatReader getHCatReader(final ReadEntity re,
final Map<String, String> config) {
// In future, this may examine ReadEntity and/or config to return
// appropriate HCatReader
return new HCatInputFormatReader(re, config);
}
/**
* This should only be called once from every slave node to obtain an instance
* of {@link HCatReader}.
*
* @param split
* input split obtained at master node
* @param config
* configuration obtained at master node
* @return {@link HCatReader}
*/
public static HCatReader getHCatReader(final InputSplit split,
final Configuration config) {
// In future, this may examine config to return appropriate HCatReader
return getHCatReader(split, config, DefaultStateProvider.get());
}
/**
* This should only be called once from every slave node to obtain an instance
* of {@link HCatReader}. This should be called if an external system has some
* state to provide to HCatalog.
*
* @param split
* input split obtained at master node
* @param config
* configuration obtained at master node
* @param sp
* {@link StateProvider}
* @return {@link HCatReader}
*/
public static HCatReader getHCatReader(final InputSplit split,
final Configuration config, StateProvider sp) {
// In future, this may examine config to return appropriate HCatReader
return new HCatInputFormatReader(split, config, sp);
}
/**
* This should be called at master node to obtain an instance of
* {@link HCatWriter}.
*
* @param we
* WriteEntity built using {@link WriteEntity.Builder}
* @param config
* any configuration which master wants to pass to HCatalog
* @return {@link HCatWriter}
*/
public static HCatWriter getHCatWriter(final WriteEntity we,
final Map<String, String> config) {
// In future, this may examine WriteEntity and/or config to return
// appropriate HCatWriter
return new HCatOutputFormatWriter(we, config);
}
/**
* This should be called at slave nodes to obtain an instance of
* {@link HCatWriter}.
*
* @param cntxt
* {@link WriterContext} obtained at master node
* @return {@link HCatWriter}
*/
public static HCatWriter getHCatWriter(final WriterContext cntxt) {
// In future, this may examine context to return appropriate HCatWriter
return getHCatWriter(cntxt, DefaultStateProvider.get());
}
/**
* This should be called at slave nodes to obtain an instance of
* {@link HCatWriter}. If an external system has some mechanism for providing
* state to HCatalog, this constructor can be used.
*
* @param cntxt
* {@link WriterContext} obtained at master node
* @param sp
* {@link StateProvider}
* @return {@link HCatWriter}
*/
public static HCatWriter getHCatWriter(final WriterContext cntxt,
final StateProvider sp) {
// In future, this may examine context to return appropriate HCatWriter
return new HCatOutputFormatWriter(cntxt.getConf(), sp);
}
}