com.google.appengine.tools.mapreduce.BlobstoreInputSplit.java Source code

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Here is the source code for com.google.appengine.tools.mapreduce.BlobstoreInputSplit.java

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/*
 * Copyright 2010 Google 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 com.google.appengine.tools.mapreduce;

import com.google.appengine.api.blobstore.BlobKey;
import com.google.common.base.Objects;
import com.google.common.base.Preconditions;

import org.apache.hadoop.io.Writable;
import org.apache.hadoop.mapreduce.InputSplit;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.util.logging.Logger;

/**
 * A writable implementation of {@code InputSplit} for BlobstoreInputFormat.
 * <p> Holds a {@code BlobKey}, {@code startIndex} and {@code endIndex}.
 *
 */
class BlobstoreInputSplit extends InputSplit implements Writable {

    private static final Logger log = Logger.getLogger(BlobstoreInputSplit.class.getName());
    private BlobKey blobKey;
    private long startIndex;
    private long endIndex;

    BlobstoreInputSplit(String key, long startIndex, long endIndex) {
        this.blobKey = new BlobKey(Preconditions.checkNotNull(key));
        this.startIndex = startIndex;
        this.endIndex = endIndex;
        checkState();
    }

    // constructor for serialization
    BlobstoreInputSplit() {
        this("", 0, 0);
    }

    // InputSplit {
    @Override
    public long getLength() {
        return getEndIndex() - getStartIndex();
    }

    @Override
    public String[] getLocations() throws IOException, InterruptedException {
        return new String[0];
    }
    // InputSplit }

    // Writable {
    @Override
    public void write(DataOutput out) throws IOException {
        log.info("Writing BlobstoreInputSplit " + this.toString());
        out.writeUTF(blobKey.getKeyString());
        out.writeLong(startIndex);
        out.writeLong(endIndex);
    }

    @Override
    public void readFields(DataInput in) throws IOException {
        blobKey = new BlobKey(Preconditions.checkNotNull(in.readUTF()));
        startIndex = in.readLong();
        endIndex = in.readLong();
        checkState();
        log.info("Initialized BlobstoreInputSplit " + this.toString());
    }
    // Writable }

    BlobKey getBlobKey() {
        return blobKey;
    }

    long getStartIndex() {
        return startIndex;
    }

    long getEndIndex() {
        return endIndex;
    }

    void checkState() {
        Preconditions.checkNotNull(blobKey);
        Preconditions.checkState(0 <= startIndex);
        Preconditions.checkState(startIndex <= endIndex);
    }

    @Override
    public int hashCode() {
        return Objects.hashCode(blobKey, startIndex, endIndex);
    }

    @Override
    public boolean equals(Object other) {
        if (this == other) {
            return true;
        }
        if (other == null || getClass() != other.getClass()) {
            return false;
        }

        BlobstoreInputSplit that = (BlobstoreInputSplit) other;

        return (this.startIndex == that.startIndex && this.endIndex == that.endIndex
                && this.blobKey.equals(that.blobKey));
    }

    @Override
    public String toString() {
        StringBuilder sb = new StringBuilder();
        sb.append("BlobstoreInputSplit");
        sb.append("{blobKey=").append(blobKey);
        sb.append(", startIndex=").append(startIndex);
        sb.append(", endIndex=").append(endIndex);
        sb.append('}');
        return sb.toString();
    }
}