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/*
* 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.drill.exec.store.hive;
import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.annotation.JsonProperty;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
/**
* Helper class that stores partition values per key.
* Key to index mapper contains key and index corresponding to partition values position in partition values list.
* Since several keys may have that same partition values, such structure is optimized to save memory usage.
* Partition values are stored in list of consecutive values.
*/
public class HivePartitionHolder {
private final Map<String, Integer> keyToIndexMapper;
private final List<List<String>> partitionValues;
@JsonCreator
public HivePartitionHolder(@JsonProperty("keyToIndexMapper") Map<String, Integer> keyToIndexMapper,
@JsonProperty("partitionValues") List<List<String>> partitionValues) {
this.keyToIndexMapper = keyToIndexMapper;
this.partitionValues = partitionValues;
}
public HivePartitionHolder() {
this.keyToIndexMapper = new HashMap<>();
this.partitionValues = new ArrayList<>();
}
@JsonProperty
public Map<String, Integer> getKeyToIndexMapper() {
return keyToIndexMapper;
}
@JsonProperty
public List<List<String>> getPartitionValues() {
return partitionValues;
}
/**
* Checks if partition values already exist in holder.
* If not, adds them to holder and adds key and index corresponding to partition values to mapper.
* If partition values exist, adds key and existing partition values index to mapper.
*
* @param key mapper key
* @param values partition values
*/
public void add(String key, List<String> values) {
int index = partitionValues.indexOf(values);
if (index == -1) {
index = partitionValues.size();
partitionValues.add(values);
}
keyToIndexMapper.put(key, index);
}
/**
* Returns list of partition values stored in holder for the given key.
* If there are no corresponding partition values, return empty list.
*
* @param key mapper key
* @return list of partition values
*/
public List<String> get(String key) {
Integer index = keyToIndexMapper.get(key);
if (index == null) {
return Collections.emptyList();
}
return partitionValues.get(index);
}
}
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