org.apache.cassandra.hadoop2.multiquery.MultiQueryInputSplit.java Source code

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Here is the source code for org.apache.cassandra.hadoop2.multiquery.MultiQueryInputSplit.java

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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.cassandra.hadoop2.multiquery;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.Set;

import com.google.common.collect.Lists;
import com.google.common.collect.Sets;
import org.apache.hadoop.io.Writable;
import org.apache.hadoop.mapreduce.InputSplit;

class MultiQueryInputSplit extends InputSplit implements Writable {
    private List<TokenRange> tokenRanges;
    private List<String> hosts;

    // TODO: Is there a better answer here?
    private static final long SPLIT_LENGTH = 1L;

    /** Not totally sure why we need this... */
    public MultiQueryInputSplit() {
    }

    public static MultiQueryInputSplit createFromSubplit(Subsplit subsplit) {
        return new MultiQueryInputSplit(Lists.newArrayList(new TokenRange(subsplit.startToken, subsplit.endToken)),
                Lists.newArrayList(subsplit.getHosts()));
    }

    public static MultiQueryInputSplit createFromSubplits(Collection<Subsplit> subsplits) {
        List<TokenRange> tokenRanges = Lists.newArrayList();
        Set<String> hosts = Sets.newHashSet();
        for (Subsplit subsplit : subsplits) {
            tokenRanges.add(new TokenRange(subsplit.getStartToken(), subsplit.getEndToken()));
            hosts.addAll(subsplit.getHosts());
        }
        return new MultiQueryInputSplit(tokenRanges, Lists.newArrayList(hosts));
    }

    private MultiQueryInputSplit(List<TokenRange> tokenRanges, List<String> hosts) {
        this.tokenRanges = tokenRanges;
        this.hosts = hosts;
    }

    public String[] getLocations() {
        return hosts.toArray(new String[hosts.size()]);
    }

    public long getLength() {
        return SPLIT_LENGTH;
    }

    // These three methods are for serializing and deserializing
    // KeyspaceSplits as needed by the Writable interface.
    public void write(DataOutput out) throws IOException {
        out.writeInt(tokenRanges.size());
        for (TokenRange tokenRange : tokenRanges) {
            out.writeUTF(tokenRange.getStartToken());
            out.writeUTF(tokenRange.getEndToken());
        }
        out.writeInt(hosts.size());
        for (String endpoint : hosts) {
            out.writeUTF(endpoint);
        }
    }

    public void readFields(DataInput in) throws IOException {
        int numTokenRanges = in.readInt();
        tokenRanges = Lists.newArrayList();
        for (int i = 0; i < numTokenRanges; i++) {
            String startToken = in.readUTF();
            String endToken = in.readUTF();
            tokenRanges.add(new TokenRange(startToken, endToken));
        }
        int numOfEndpoints = in.readInt();
        hosts = Lists.newArrayList();
        for (int i = 0; i < numOfEndpoints; i++) {
            hosts.add(in.readUTF());
        }
    }

    @Override
    public String toString() {
        return String.format("MultiqueryInputSplit(%s)", hosts);
    }

    public Iterator<TokenRange> getTokenRangeIterator() {
        return tokenRanges.iterator();
    }
}