co.cask.cdap.etl.api.lookup.KeyValueTableLookup.java Source code

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Here is the source code for co.cask.cdap.etl.api.lookup.KeyValueTableLookup.java

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/*
 * Copyright  2015 Cask Data, Inc.
 *
 * 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 co.cask.cdap.etl.api.lookup;

import co.cask.cdap.api.common.Bytes;
import co.cask.cdap.api.dataset.lib.KeyValueTable;
import co.cask.cdap.etl.api.Lookup;
import com.google.common.collect.ImmutableSet;

import java.util.HashMap;
import java.util.Map;
import java.util.Set;

/**
 * {@link Lookup} implementation for {@link KeyValueTable}.
 */
public class KeyValueTableLookup implements Lookup<String> {

    private final KeyValueTable table;

    public KeyValueTableLookup(KeyValueTable table) {
        this.table = table;
    }

    @Override
    public String lookup(String key) {
        return Bytes.toString(table.read(key));
    }

    @Override
    public Map<String, String> lookup(String... keys) {
        return lookup(ImmutableSet.copyOf(keys));
    }

    @Override
    public Map<String, String> lookup(Set<String> keys) {
        return fromBytes(table.readAll(toBytes(keys)));
    }

    private Map<String, String> fromBytes(Map<byte[], byte[]> bytes) {
        Map<String, String> result = new HashMap<>();
        for (Map.Entry<byte[], byte[]> entry : bytes.entrySet()) {
            result.put(Bytes.toString(entry.getKey()), Bytes.toString(entry.getValue()));
        }
        return result;
    }

    private byte[][] toBytes(Set<String> keys) {
        byte[][] result = new byte[keys.size()][];

        int i = 0;
        for (String key : keys) {
            result[i++] = Bytes.toBytes(key);
        }
        return result;
    }
}