reswqa commented on code in PR #19960: URL: https://github.com/apache/flink/pull/19960#discussion_r915441265
########## flink-runtime/src/main/java/org/apache/flink/runtime/io/network/partition/hybrid/HsSubpartitionFileReader.java: ########## @@ -0,0 +1,416 @@ +/* + * 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.runtime.io.network.partition.hybrid; + +import org.apache.flink.api.java.tuple.Tuple2; +import org.apache.flink.core.memory.MemorySegment; +import org.apache.flink.runtime.io.network.buffer.Buffer; +import org.apache.flink.runtime.io.network.buffer.BufferRecycler; +import org.apache.flink.runtime.io.network.partition.BufferReaderWriterUtil; + +import javax.annotation.Nullable; + +import java.io.IOException; +import java.nio.ByteBuffer; +import java.nio.channels.FileChannel; +import java.util.Deque; +import java.util.Objects; +import java.util.Optional; +import java.util.Queue; +import java.util.concurrent.LinkedBlockingDeque; + +import static org.apache.flink.runtime.io.network.partition.BufferReaderWriterUtil.positionToNextBuffer; +import static org.apache.flink.runtime.io.network.partition.BufferReaderWriterUtil.readFromByteChannel; +import static org.apache.flink.util.Preconditions.checkArgument; +import static org.apache.flink.util.Preconditions.checkNotNull; +import static org.apache.flink.util.Preconditions.checkState; + +/** + * This component is responsible for reading data from disk for a specific subpartition. + * + * <p>In order to access the disk as sequentially as possible {@link HsSubpartitionFileReader} need + * to be able to compare priorities. + * + * <p>Note: This class is not thread safe. + */ +public class HsSubpartitionFileReader implements SubpartitionFileReader { + + private final ByteBuffer headerBuf = BufferReaderWriterUtil.allocatedHeaderBuffer(); + + private final int subpartitionId; + + private final FileChannel dataFileChannel; + + private final HsSubpartitionViewInternalOperations operations; + + private final CachedRegionManager cachedRegionManager; + + private final BufferIndexManager bufferIndexManager; + + private final Deque<BufferIndexOrError> loadedBuffers = new LinkedBlockingDeque<>(); + + private volatile boolean isFailed; + + public HsSubpartitionFileReader( + int subpartitionId, + FileChannel dataFileChannel, + HsSubpartitionViewInternalOperations operations, + HsFileDataIndex dataIndex, + int maxBufferReadAhead) { + this.subpartitionId = subpartitionId; + this.dataFileChannel = dataFileChannel; + this.operations = operations; + this.bufferIndexManager = new BufferIndexManager(maxBufferReadAhead); + this.cachedRegionManager = new CachedRegionManager(subpartitionId, dataIndex); + } + + @Override + public boolean equals(Object o) { + if (this == o) { + return true; + } + if (o == null || getClass() != o.getClass()) { + return false; + } + HsSubpartitionFileReader that = (HsSubpartitionFileReader) o; + return subpartitionId == that.subpartitionId; + } + + @Override + public int hashCode() { + return Objects.hash(subpartitionId); + } + + /** + * Read subpartition data into buffers. + * + * <p>This transfers the ownership of used buffers to this class. It's this class' + * responsibility to release the buffers using the recycler when no longer needed. + * + * <p>Calling this method does not always use up all the provided buffers. It's this class' + * decision when to stop reading. Currently, it stops reading when: 1) buffers are used up, or + * 2) reaches the end of the subpartition data within the region, or 3) enough data have been + * read ahead the downstream consuming offset. + */ + @Override + public synchronized void readBuffers(Queue<MemorySegment> buffers, BufferRecycler recycler) + throws IOException { + if (isFailed) { + throw new IOException("subpartition reader has already failed."); + } + int firstBufferToLoad = bufferIndexManager.getNextToLoad(); + if (firstBufferToLoad < 0) { + return; + } + + // If lookup result is empty, it means that one the following things have happened: + // 1) The target buffer has not been spilled into disk. + // 2) The target buffer has not been released from memory. + // So, just skip this round reading. + int numRemainingBuffer = cachedRegionManager.getRemainingBuffersInRegion(firstBufferToLoad); + if (numRemainingBuffer == 0) { + return; + } + moveFileOffsetToBuffer(firstBufferToLoad); + + int indexToLoad; + int numLoaded = 0; + while (!buffers.isEmpty() + && (indexToLoad = bufferIndexManager.getNextToLoad()) >= 0 + && numRemainingBuffer-- > 0) { + MemorySegment segment = buffers.poll(); + Buffer buffer; + try { + if ((buffer = readFromByteChannel(dataFileChannel, headerBuf, segment, recycler)) + == null) { + buffers.add(segment); + break; + } + } catch (Throwable throwable) { + buffers.add(segment); + throw throwable; + } + + loadedBuffers.add(BufferIndexOrError.newBuffer(buffer, indexToLoad)); + bufferIndexManager.updateLastLoaded(indexToLoad); + cachedRegionManager.advance( + buffer.readableBytes() + BufferReaderWriterUtil.HEADER_LENGTH); + ++numLoaded; + } + + if (loadedBuffers.size() <= numLoaded) { + operations.notifyDataAvailableFromDisk(); + } + } + + @Override + public synchronized void fail(Throwable failureCause) { + if (isFailed) { + return; + } + isFailed = true; + BufferIndexOrError bufferIndexOrError; + // empty from tail, in-case subpartition view consumes concurrently and gets the wrong order + while ((bufferIndexOrError = loadedBuffers.pollLast()) != null) { + if (bufferIndexOrError.getBuffer().isPresent()) { + checkNotNull(bufferIndexOrError.buffer).recycleBuffer(); + } + } + + loadedBuffers.add(BufferIndexOrError.newError(failureCause)); + operations.notifyDataAvailableFromDisk(); + } + + @Override + public void prepareForScheduling() { + updateConsumptionProgress(); + } + + public Deque<BufferIndexOrError> getLoadedBuffers() { + return loadedBuffers; + } + + // ------------------------------------------------------------------------ + // Internal Methods + // ------------------------------------------------------------------------ + + /** Refresh downstream consumption progress for another round scheduling of reading. */ + private void updateConsumptionProgress() { + bufferIndexManager.updateLastConsumed(operations.getConsumingOffset()); + } + + private void moveFileOffsetToBuffer(int bufferIndex) throws IOException { + Tuple2<Integer, Long> indexAndOffset = + cachedRegionManager.getNumSkipAndFileOffset(bufferIndex); + dataFileChannel.position(indexAndOffset.f1); + for (int i = 0; i < indexAndOffset.f0; ++i) { + positionToNextBuffer(dataFileChannel, headerBuf); + } + cachedRegionManager.skipAll(dataFileChannel.position()); + } + + /** Returns Long.MAX_VALUE if it shouldn't load. */ + private long getNextOffsetToLoad() { + int bufferIndex = bufferIndexManager.getNextToLoad(); + if (bufferIndex < 0) { + return Long.MAX_VALUE; + } else { + return cachedRegionManager.getFileOffset(bufferIndex); + } + } + + /** Provides priority calculation logic for io scheduler. */ + @Override + public int compareTo(SubpartitionFileReader that) { Review Comment: good catch. -- This is an automated message from the Apache Git Service. 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