org.apache.hadoop.hdfs.StatefulStripeReader 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.hadoop.hdfs;
import com.google.common.base.Preconditions;
import org.apache.hadoop.hdfs.protocol.ErasureCodingPolicy;
import org.apache.hadoop.hdfs.protocol.LocatedBlock;
import org.apache.hadoop.hdfs.util.StripedBlockUtil;
import org.apache.hadoop.hdfs.util.StripedBlockUtil.StripingChunk;
import org.apache.hadoop.hdfs.util.StripedBlockUtil.AlignedStripe;
import org.apache.hadoop.io.erasurecode.ECChunk;
import org.apache.hadoop.io.erasurecode.rawcoder.RawErasureDecoder;
import org.apache.hadoop.hdfs.DFSUtilClient.CorruptedBlocks;
import java.io.IOException;
import java.nio.ByteBuffer;
/**
* The reader for reading a complete {@link StripedBlockUtil.AlignedStripe}
* which belongs to a single stripe.
* Reading cross multiple strips is not supported in this reader.
*/
class StatefulStripeReader extends StripeReader {
StatefulStripeReader(AlignedStripe alignedStripe,
ErasureCodingPolicy ecPolicy, LocatedBlock[] targetBlocks,
BlockReaderInfo[] readerInfos, CorruptedBlocks corruptedBlocks,
RawErasureDecoder decoder, DFSStripedInputStream dfsStripedInputStream) {
super(alignedStripe, ecPolicy, targetBlocks, readerInfos,
corruptedBlocks, decoder, dfsStripedInputStream);
}
@Override
void prepareDecodeInputs() {
final ByteBuffer cur;
synchronized (dfsStripedInputStream) {
cur = dfsStripedInputStream.getCurStripeBuf().duplicate();
}
this.decodeInputs = new ECChunk[dataBlkNum + parityBlkNum];
int bufLen = (int) alignedStripe.getSpanInBlock();
int bufOff = (int) alignedStripe.getOffsetInBlock();
for (int i = 0; i < dataBlkNum; i++) {
cur.limit(cur.capacity());
int pos = bufOff % cellSize + cellSize * i;
cur.position(pos);
cur.limit(pos + bufLen);
decodeInputs[i] = new ECChunk(cur.slice(), 0, bufLen);
if (alignedStripe.chunks[i] == null) {
alignedStripe.chunks[i] =
new StripingChunk(decodeInputs[i].getBuffer());
}
}
}
@Override
boolean prepareParityChunk(int index) {
Preconditions.checkState(index >= dataBlkNum
&& alignedStripe.chunks[index] == null);
if (readerInfos[index] != null && readerInfos[index].shouldSkip) {
alignedStripe.chunks[index] = new StripingChunk(StripingChunk.MISSING);
// we have failed the block reader before
return false;
}
final int parityIndex = index - dataBlkNum;
ByteBuffer buf = dfsStripedInputStream.getParityBuffer().duplicate();
buf.position(cellSize * parityIndex);
buf.limit(cellSize * parityIndex + (int) alignedStripe.range.spanInBlock);
decodeInputs[index] =
new ECChunk(buf.slice(), 0, (int) alignedStripe.range.spanInBlock);
alignedStripe.chunks[index] =
new StripingChunk(decodeInputs[index].getBuffer());
return true;
}
@Override
void decode() throws IOException {
finalizeDecodeInputs();
decodeAndFillBuffer(false);
}
}