org.apache.flink.iteration.datacache.nonkeyed.DataCacheReader Maven / Gradle / Ivy
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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.flink.iteration.datacache.nonkeyed;
import org.apache.flink.api.common.typeutils.TypeSerializer;
import org.apache.flink.api.java.tuple.Tuple2;
import javax.annotation.Nullable;
import java.io.IOException;
import java.util.Iterator;
import java.util.List;
/** Reads the cached data from a list of segments. */
public class DataCacheReader implements Iterator {
/** The tool to deserialize bytes into records. */
private final TypeSerializer serializer;
/** The segments where to read the records from. */
private final List segments;
/** The current reader for next records. */
@Nullable private SegmentReader currentSegmentReader;
/** The index of the segment that current reader reads from. */
private int currentSegmentIndex;
/** The number of records that have been read through the current reader so far. */
private int currentSegmentCount;
public DataCacheReader(TypeSerializer serializer, List segments) {
this(serializer, segments, Tuple2.of(0, 0));
}
public DataCacheReader(
TypeSerializer serializer,
List segments,
Tuple2 readerPosition) {
this.serializer = serializer;
this.segments = segments;
this.currentSegmentIndex = readerPosition.f0;
this.currentSegmentCount = readerPosition.f1;
createSegmentReader(readerPosition.f0, readerPosition.f1);
}
@Override
public boolean hasNext() {
return currentSegmentReader != null && currentSegmentReader.hasNext();
}
@Override
public T next() {
try {
T record = currentSegmentReader.next();
currentSegmentCount++;
if (!currentSegmentReader.hasNext()) {
currentSegmentReader.close();
currentSegmentIndex++;
currentSegmentCount = 0;
createSegmentReader(currentSegmentIndex, currentSegmentCount);
}
return record;
} catch (IOException e) {
throw new RuntimeException(e);
}
}
public Tuple2 getPosition() {
return new Tuple2<>(currentSegmentIndex, currentSegmentCount);
}
private void createSegmentReader(int index, int startOffset) {
try {
if (index >= segments.size()) {
currentSegmentReader = null;
return;
}
Segment segment = segments.get(currentSegmentIndex);
if (!segment.getCache().isEmpty()) {
currentSegmentReader = new MemorySegmentReader<>(serializer, segment, startOffset);
} else {
currentSegmentReader = new FileSegmentReader<>(serializer, segment, startOffset);
}
} catch (IOException e) {
throw new RuntimeException(e);
}
}
}