mumrah commented on a change in pull request #9008: URL: https://github.com/apache/kafka/pull/9008#discussion_r457416269
########## File path: clients/src/main/java/org/apache/kafka/common/protocol/RecordsWriter.java ########## @@ -0,0 +1,169 @@ +/* + * 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.kafka.common.protocol; + +import org.apache.kafka.common.network.ByteBufferSend; +import org.apache.kafka.common.network.Send; +import org.apache.kafka.common.record.BaseRecords; +import org.apache.kafka.common.utils.ByteBufferOutputStream; +import org.apache.kafka.common.utils.ByteUtils; + +import java.io.DataOutput; +import java.io.DataOutputStream; +import java.io.IOException; +import java.nio.ByteBuffer; +import java.util.function.Consumer; + +/** + * Implementation of Writable which produces a sequence of {@link Send} objects. This allows for deferring the transfer + * of data from a record-set's file channel to the eventual socket channel. + * + * Excepting {@link #writeRecords(BaseRecords)}, calls to the write methods on this class will append to a byte array + * according to the format specified in {@link DataOutput}. When a call is made to writeRecords, any previously written + * bytes will be flushed as a new {@link ByteBufferSend} to the given Send consumer. After flushing the pending bytes, + * another Send is passed to the consumer which wraps the underlying record-set's transfer logic. + * + * For example, + * + * <pre> + * recordsWritable.writeInt(10); + * recordsWritable.writeRecords(records1); + * recordsWritable.writeInt(20); + * recordsWritable.writeRecords(records2); + * recordsWritable.writeInt(30); + * recordsWritable.flush(); + * </pre> + * + * Will pass 5 Send objects to the consumer given in the constructor. Care must be taken by callers to flush any + * pending bytes at the end of the writing sequence to ensure everything is flushed to the consumer. This class is + * intended to be used with {@link org.apache.kafka.common.record.MultiRecordsSend}. + * + * @see org.apache.kafka.common.requests.FetchResponse + */ +public class RecordsWriter implements Writable { + private final String dest; + private final Consumer<Send> sendConsumer; + private final ByteBufferOutputStream byteArrayOutputStream; + private final DataOutput output; + private int mark; + + public RecordsWriter(String dest, Consumer<Send> sendConsumer) { + this.dest = dest; + this.sendConsumer = sendConsumer; + this.byteArrayOutputStream = new ByteBufferOutputStream(32); + this.output = new DataOutputStream(this.byteArrayOutputStream); + this.mark = 0; + } + + @Override + public void writeByte(byte val) { + try { + output.writeByte(val); + } catch (IOException e) { + throw new RuntimeException("RecordsWriter encountered an IO error", e); + } + } + + @Override + public void writeShort(short val) { + try { + output.writeShort(val); + } catch (IOException e) { + throw new RuntimeException("RecordsWriter encountered an IO error", e); + } + } + + @Override + public void writeInt(int val) { + try { + output.writeInt(val); + } catch (IOException e) { + throw new RuntimeException("RecordsWriter encountered an IO error", e); + } + } + + @Override + public void writeLong(long val) { + try { + output.writeLong(val); + } catch (IOException e) { + throw new RuntimeException("RecordsWriter encountered an IO error", e); + } + } + + @Override + public void writeDouble(double val) { + try { + ByteUtils.writeDouble(val, output); + } catch (IOException e) { + throw new RuntimeException("RecordsWriter encountered an IO error", e); + } + } + + @Override + public void writeByteArray(byte[] arr) { + try { + output.write(arr); + } catch (IOException e) { + throw new RuntimeException("RecordsWriter encountered an IO error", e); + } + } + + @Override + public void writeUnsignedVarint(int i) { + try { + ByteUtils.writeUnsignedVarint(i, output); + } catch (IOException e) { + throw new RuntimeException("RecordsWriter encountered an IO error", e); + } + } + + @Override + public void writeByteBuffer(ByteBuffer src) { + try { + output.write(src.array(), src.position(), src.remaining()); + } catch (IOException e) { + throw new RuntimeException("RecordsWriter encountered an IO error", e); + } + } + + public void writeRecords(BaseRecords records) { + flush(); + sendConsumer.accept(records.toSend(dest)); + } + + /** + * Flush any pending bytes as a ByteBufferSend and reset the buffer + */ + public void flush() { + ByteBuffer buf = byteArrayOutputStream.buffer(); + int end = buf.position(); + int len = end - mark; + + if (len > 0) { + buf.position(mark); + ByteBuffer slice = buf.slice(); + slice.limit(len); + ByteBufferSend send = new ByteBufferSend(dest, slice); + sendConsumer.accept(send); + } + + buf.position(end); + mark = end; Review comment: I ended up having to keep a separate mark here since ByteBufferOutputStream doesn't keep the mark when it replaces the underlying buffer. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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