org.apache.hama.bsp.join.CompositeInputSplit.java Source code

Introduction

Here is the source code for org.apache.hama.bsp.join.CompositeInputSplit.java

Source

/**
 * 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.hama.bsp.join;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.util.HashSet;

import org.apache.hadoop.io.Text;
import org.apache.hadoop.io.WritableUtils;
import org.apache.hadoop.util.ReflectionUtils;
import org.apache.hama.bsp.InputSplit;

/**
 * This InputSplit contains a set of child InputSplits. Any InputSplit inserted
 * into this collection must have a public default constructor.
 */
public class CompositeInputSplit implements InputSplit {

    private int fill = 0;
    private long totsize = 0L;
    private InputSplit[] splits;

    public CompositeInputSplit() {
    }

    public CompositeInputSplit(int capacity) {
        splits = new InputSplit[capacity];
    }

    /**
     * Add an InputSplit to this collection.
     * 
     * @throws IOException If capacity was not specified during construction or if
     *           capacity has been reached.
     */
    public void add(InputSplit s) throws IOException {
        if (null == splits) {
            throw new IOException("Uninitialized InputSplit");
        }
        if (fill == splits.length) {
            throw new IOException("Too many splits");
        }
        splits[fill++] = s;
        totsize += s.getLength();
    }

    /**
     * Get ith child InputSplit.
     */
    public InputSplit get(int i) {
        return splits[i];
    }

    /**
     * Return the aggregate length of all child InputSplits currently added.
     */
    public long getLength() throws IOException {
        return totsize;
    }

    /**
     * Get the length of ith child InputSplit.
     */
    public long getLength(int i) throws IOException {
        return splits[i].getLength();
    }

    /**
     * Collect a set of hosts from all child InputSplits.
     */
    public String[] getLocations() throws IOException {
        HashSet<String> hosts = new HashSet<String>();
        for (InputSplit s : splits) {
            String[] hints = s.getLocations();
            if (hints != null && hints.length > 0) {
                for (String host : hints) {
                    hosts.add(host);
                }
            }
        }
        return hosts.toArray(new String[hosts.size()]);
    }

    /**
     * getLocations from ith InputSplit.
     */
    public String[] getLocation(int i) throws IOException {
        return splits[i].getLocations();
    }

    /**
     * Write splits in the following format.
     * {@code
     * <count><class1><class2>...<classn><split1><split2>...<splitn>
     * }
     */
    public void write(DataOutput out) throws IOException {
        WritableUtils.writeVInt(out, splits.length);
        for (InputSplit s : splits) {
            Text.writeString(out, s.getClass().getName());
        }
        for (InputSplit s : splits) {
            s.write(out);
        }
    }

    /**
     * {@inheritDoc}
     * 
     * @throws IOException If the child InputSplit cannot be read, typically for
     *           faliing access checks.
     */
    @SuppressWarnings("unchecked")
    // Generic array assignment
    public void readFields(DataInput in) throws IOException {
        int card = WritableUtils.readVInt(in);
        if (splits == null || splits.length != card) {
            splits = new InputSplit[card];
        }
        Class<? extends InputSplit>[] cls = new Class[card];
        try {
            for (int i = 0; i < card; ++i) {
                cls[i] = Class.forName(Text.readString(in)).asSubclass(InputSplit.class);
            }
            for (int i = 0; i < card; ++i) {
                splits[i] = ReflectionUtils.newInstance(cls[i], null);
                splits[i].readFields(in);
            }
        } catch (ClassNotFoundException e) {
            throw (IOException) new IOException("Failed split init").initCause(e);
        }
    }

}