/*
* 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.data.stream;
import co.cask.cdap.api.flow.flowlet.StreamEvent;
import co.cask.cdap.api.stream.StreamEventDecoder;
import co.cask.cdap.common.io.Locations;
import com.google.common.collect.Lists;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.mapreduce.InputSplit;
import org.apache.hadoop.mapreduce.RecordReader;
import org.apache.hadoop.mapreduce.TaskAttemptContext;
import java.io.IOException;
import java.util.List;
import java.util.concurrent.TimeUnit;
/**
* A {@link RecordReader} for reading stream events.
*
* @param <K> Key type read by this record reader.
* @param <V> Value type read by this record reader.
*/
final class StreamRecordReader<K, V> extends RecordReader<K, V> {
private final StreamEventDecoder<K, V> decoder;
private final List<StreamEvent> events;
private StreamDataFileReader reader;
private StreamInputSplit inputSplit;
private StreamEventDecoder.DecodeResult<K, V> currentEntry;
/**
* Construct a {@link StreamRecordReader} with a given {@link StreamEventDecoder}.
*
* @param decoder The decoder to use for decoding stream events.
*/
StreamRecordReader(StreamEventDecoder<K, V> decoder) {
this.decoder = decoder;
this.events = Lists.newArrayListWithCapacity(1);
this.currentEntry = new StreamEventDecoder.DecodeResult<K, V>();
}
@Override
public void initialize(InputSplit split, TaskAttemptContext context) throws IOException, InterruptedException {
inputSplit = (StreamInputSplit) split;
reader = createReader(FileSystem.get(context.getConfiguration()), inputSplit);
reader.initialize();
}
@Override
public boolean nextKeyValue() throws IOException, InterruptedException {
StreamEvent streamEvent;
do {
if (reader.getPosition() >= inputSplit.getStart() + inputSplit.getLength()) {
return false;
}
events.clear();
if (reader.read(events, 1, 0, TimeUnit.SECONDS) <= 0) {
return false;
}
streamEvent = events.get(0);
} while (streamEvent.getTimestamp() < inputSplit.getStartTime());
if (streamEvent.getTimestamp() >= inputSplit.getEndTime()) {
return false;
}
currentEntry = decoder.decode(streamEvent, currentEntry);
return true;
}
@Override
public K getCurrentKey() throws IOException, InterruptedException {
return currentEntry.getKey();
}
@Override
public V getCurrentValue() throws IOException, InterruptedException {
return currentEntry.getValue();
}
@Override
public float getProgress() throws IOException, InterruptedException {
if (reader == null) {
return 0.0f;
}
long processed = reader.getPosition() - inputSplit.getStart();
return Math.min((float) processed / (float) inputSplit.getLength(), 1.0f);
}
@Override
public void close() throws IOException {
if (reader != null) {
reader.close();
}
}
/**
* Creates a {@link StreamDataFileReader} based on the input split.
*
* @param fs The {@link FileSystem} for the input.
* @param inputSplit Split information.
* @return A {@link StreamRecordReader} that is ready for reading events as specified by the input split.
*/
private StreamDataFileReader createReader(FileSystem fs, StreamInputSplit inputSplit) {
return StreamDataFileReader.createWithOffset(Locations.newInputSupplier(fs, inputSplit.getPath()),
Locations.newInputSupplier(fs, inputSplit.getIndexPath()),
inputSplit.getStart());
}
}