wsry commented on a change in pull request #13595: URL: https://github.com/apache/flink/pull/13595#discussion_r511591782
########## File path: flink-runtime/src/main/java/org/apache/flink/runtime/io/network/partition/PartitionSortedBuffer.java ########## @@ -0,0 +1,390 @@ +/* + * 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; + +import org.apache.flink.core.memory.MemorySegment; +import org.apache.flink.core.memory.MemorySegmentFactory; +import org.apache.flink.runtime.io.network.buffer.Buffer; +import org.apache.flink.runtime.io.network.buffer.BufferBuilder; +import org.apache.flink.runtime.io.network.buffer.BufferPool; +import org.apache.flink.runtime.io.network.buffer.NetworkBuffer; + +import javax.annotation.concurrent.NotThreadSafe; + +import java.io.IOException; +import java.nio.ByteBuffer; +import java.util.ArrayList; +import java.util.Arrays; + +import static org.apache.flink.runtime.io.network.buffer.Buffer.DataType; +import static org.apache.flink.util.Preconditions.checkArgument; +import static org.apache.flink.util.Preconditions.checkNotNull; +import static org.apache.flink.util.Preconditions.checkState; + +/** + * A {@link SortBuffer} implementation which sorts all appended records only by subpartition index. Records of the + * same subpartition keep the appended order. + * + * <p>It maintains a list of {@link MemorySegment}s as a joint buffer. Data will be appended to the joint buffer + * sequentially. When writing a record, an index entry will be appended first. Each index entry has 4 fields: 4 + * bytes record length, 4 bytes {@link DataType} and 8 bytes address pointing to the next index entry of the same + * channel which will be used to index the next record to read when coping data from this {@link SortBuffer}. For + * simplicity, no index entry can span multiple segments. The corresponding record data sits right after its index + * entry and different from the index entry, records have variable length thus may span multiple segments. + */ +@NotThreadSafe +public class PartitionSortedBuffer implements SortBuffer { + + /** + * Size of an index entry: 4 bytes for record length, 4 bytes for data type and 8 bytes + * for pointer to next entry. + */ + private static final int INDEX_ENTRY_SIZE = 4 + 4 + 8; + + /** A buffer pool to request memory segments from. */ + private final BufferPool bufferPool; + + /** A segment list as a joint buffer which stores all records and index entries. */ + private final ArrayList<MemorySegment> buffers = new ArrayList<>(); + + /** Addresses of the first record's index entry for each subpartition. */ + private final long[] firstIndexEntryAddresses; + + /** Addresses of the last record's index entry for each subpartition. */ + private final long[] lastIndexEntryAddresses; + + /** Size of buffers requested from buffer pool. All buffers must be of the same size. */ + private final int bufferSize; + + // ---------------------------------------------------------------------------------------------- + // Statistics and states + // ---------------------------------------------------------------------------------------------- + + /** Total number of bytes already appended to this sort buffer. */ + private long numTotalBytes; + + /** Total number of records already appended to this sort buffer. */ + private long numTotalRecords; + + /** Total number of bytes already read from this sort buffer. */ + private long numTotalBytesRead; + + /** Whether this sort buffer is finished. One can only read a finished sort buffer. */ + private boolean isFinished; + + /** Whether this sort buffer is released. A released sort buffer can not be used. */ + private boolean isReleased; + + // ---------------------------------------------------------------------------------------------- + // For writing + // ---------------------------------------------------------------------------------------------- + + /** Array index in the segment list of the current available buffer for writing. */ + private int writeSegmentIndex; + + /** Next position in the current available buffer for writing. */ + private int writeSegmentOffset; + + // ---------------------------------------------------------------------------------------------- + // For reading + // ---------------------------------------------------------------------------------------------- + + /** Index entry address of the current record or event to be read. */ + private long readIndexEntryAddress; + + /** Record bytes remaining after last copy, which must be read first in next copy. */ + private int recordRemainingBytes; + + /** Current available channel to read data from. */ + private int readChannelIndex = -1; + + public PartitionSortedBuffer(BufferPool bufferPool, int numSubpartitions, int bufferSize) { + checkArgument(bufferSize > INDEX_ENTRY_SIZE, "Buffer size is too small."); + + this.bufferPool = checkNotNull(bufferPool); + this.bufferSize = bufferSize; + this.firstIndexEntryAddresses = new long[numSubpartitions]; + this.lastIndexEntryAddresses = new long[numSubpartitions]; + + // initialized with -1 means the corresponding channel has no data + Arrays.fill(firstIndexEntryAddresses, -1L); + Arrays.fill(lastIndexEntryAddresses, -1L); + } + + @Override + public boolean append(ByteBuffer source, int targetChannel, DataType dataType) throws IOException { + checkState(!isFinished, "Sort buffer is already finished."); + checkState(!isReleased, "Sort buffer is already released."); + + int totalBytes = source.remaining(); + if (totalBytes == 0) { Review comment: Empty record is impossible here, I will add a check here. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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