co.cask.cdap.hive.stream.StreamInputSplit.java Source code

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Here is the source code for co.cask.cdap.hive.stream.StreamInputSplit.java

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/*
 * Copyright  2014 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.hive.stream;

import com.google.common.base.Objects;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.Writable;
import org.apache.hadoop.io.WritableUtils;
import org.apache.hadoop.mapred.FileSplit;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import javax.annotation.Nullable;

/**
 * Represents a mapred InputSplit for stream. This class must extends from {@link FileSplit}, since Hive expected so.
 * For Stream, since we have all the knowledge in the storage handler about the stream
 * location (and is dynamic due to advancement in stream generation id due to truncation), there is no point to
 * use LOCATION in the table. However, for external table in Hive, if LOCATION was not set during table creation
 * time, Hive will assume the location to be some internally managed path and will fail the query job if
 * {@link #getPath()} doesn't return a Path that is located inside the Hive internal path. Because of this
 * behavior, the StreamInputSplit {@link #getPath()} returns a dummy path which always match with what Hive wanted, but
 * the {@link HiveStreamInputFormat} never use it, but using {@link #getEventPath()} instead.
 */
public final class StreamInputSplit extends FileSplit implements Writable {

    private Path eventPath;
    private Path indexPath;
    private long startTime;
    private long endTime;

    /**
     * Default constructor. Called by MapReduce framework only.
     */
    public StreamInputSplit() {
        // No-op
    }

    /**
     * Constructs a split.
     *
     * @param path the hive file path. Never used by {@link HiveStreamInputFormat}; it is just to satisfy hive.
     * @param eventPath Path for the stream event file.
     * @param indexPath Path for the stream index file.
     * @param startTime Event start timestamp in milliseconds (inclusive).
     * @param endTime Event end timestamp in milliseconds (exclusive).
     * @param start Starting offset in the stream event file. It can be arbitrary offset, no need to align to event start.
     * @param length Size of this split.
     * @param locations List of hosts containing this split.
     */
    StreamInputSplit(Path path, Path eventPath, @Nullable Path indexPath, long startTime, long endTime, long start,
            long length, @Nullable String[] locations) {
        super(path, start, length, locations);
        this.eventPath = eventPath;
        this.indexPath = indexPath;
        this.startTime = startTime;
        this.endTime = endTime;
    }

    /**
     * @deprecated Use {@link #getEventPath()} instead.
     */
    @Deprecated
    @Override
    public Path getPath() {
        return super.getPath();
    }

    public Path getEventPath() {
        return eventPath;
    }

    /**
     * Returns the path for index file.
     */
    @Nullable
    public Path getIndexPath() {
        return indexPath;
    }

    /**
     * Returns the event start timestamp in milliseconds.
     */
    long getStartTime() {
        return startTime;
    }

    /**
     * Returns the event end timestamp in milliseconds.
     */
    long getEndTime() {
        return endTime;
    }

    @Override
    public void write(DataOutput out) throws IOException {
        super.write(out);
        WritableUtils.writeString(out, eventPath.toString());
        if (indexPath == null) {
            out.writeBoolean(false);
        } else {
            out.writeBoolean(true);
            WritableUtils.writeString(out, indexPath.toString());
        }
        WritableUtils.writeVLong(out, startTime);
        WritableUtils.writeVLong(out, endTime);
    }

    @Override
    public void readFields(DataInput in) throws IOException {
        super.readFields(in);
        eventPath = new Path(WritableUtils.readString(in));
        boolean hasIndex = in.readBoolean();
        if (hasIndex) {
            indexPath = new Path(WritableUtils.readString(in));
        }
        startTime = WritableUtils.readVLong(in);
        endTime = WritableUtils.readVLong(in);
    }

    @Override
    public String toString() {
        return Objects.toStringHelper(this).add("path", getPath()).add("index", getIndexPath())
                .add("start", getStart()).add("length", getLength()).add("startTime", getStartTime())
                .add("endTime", getEndTime()).toString();
    }
}