AHeise commented on a change in pull request #11515: [FLINK-16744][task] implement channel state persistence for unaligned checkpoints URL: https://github.com/apache/flink/pull/11515#discussion_r400946915
########## File path: flink-runtime/src/main/java/org/apache/flink/runtime/checkpoint/channel/ChannelStateStreamReader.java ########## @@ -0,0 +1,117 @@ +/* + * 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.checkpoint.channel; + +import org.apache.flink.api.java.tuple.Tuple2; +import org.apache.flink.runtime.checkpoint.channel.ChannelStateReader.ReadResult; +import org.apache.flink.runtime.checkpoint.channel.RefCountingFSDataInputStream.RefCountingFSDataInputStreamFactory; +import org.apache.flink.runtime.io.network.buffer.Buffer; +import org.apache.flink.runtime.io.network.buffer.BufferBuilder; +import org.apache.flink.runtime.state.AbstractChannelStateHandle; +import org.apache.flink.util.Preconditions; + +import javax.annotation.concurrent.NotThreadSafe; + +import java.io.Closeable; +import java.io.IOException; +import java.util.LinkedList; +import java.util.List; +import java.util.Queue; + +import static java.lang.Math.addExact; +import static org.apache.flink.runtime.checkpoint.channel.ChannelStateByteBuffer.wrap; +import static org.apache.flink.runtime.checkpoint.channel.ChannelStateReader.ReadResult.HAS_MORE_DATA; +import static org.apache.flink.runtime.checkpoint.channel.ChannelStateReader.ReadResult.NO_MORE_DATA; + +/** + * Reads the state of a single channel pointed by {@link org.apache.flink.runtime.state.AbstractChannelStateHandle AbstractChannelStateHandle}. + * Single-use. + * Uses {@link RefCountingFSDataInputStream} internally. + */ +@NotThreadSafe +class ChannelStateStreamReader implements Closeable { + + private final RefCountingFSDataInputStream stream; // todo: buffer? + private final Queue<Long> offsets; + private final ChannelStateDeserializer serializer; + private long pos = -1; + private int rem; + private boolean closed = false; + + ChannelStateStreamReader(AbstractChannelStateHandle<?> handle, RefCountingFSDataInputStreamFactory streamFactory) { + this(streamFactory.forHandle(handle), handle.getOffsets(), streamFactory.getSerializer()); + } + + private ChannelStateStreamReader(RefCountingFSDataInputStream stream, List<Long> offsets, ChannelStateDeserializer serializer) { + this.stream = stream; + this.stream.incNumReaders(); + this.serializer = serializer; + this.offsets = new LinkedList<>(offsets); + } + + ReadResult readInto(Buffer buffer) throws IOException { + return readInto(wrap(buffer)); + } + + ReadResult readInto(BufferBuilder bufferBuilder) throws IOException { + return readInto(wrap(bufferBuilder)); + } + + private ReadResult readInto(ChannelStateByteBuffer buffer) throws IOException { + Preconditions.checkState(!closed, "reader is closed"); + readWhilePossible(buffer); + if (haveMoreData()) { + return HAS_MORE_DATA; + } else { + close(); + return NO_MORE_DATA; + } + } + + private void readWhilePossible(ChannelStateByteBuffer buffer) throws IOException { + while (haveMoreData() && buffer.isWritable()) { + if (pos < 0 || rem <= 0) { + advanceOffset(); + } + int bytesRead = serializer.readData(stream, buffer, rem); + rem -= bytesRead; + pos = addExact(pos, bytesRead); + } + } + + private boolean haveMoreData() { + return rem > 0 || !offsets.isEmpty(); + } + + private void advanceOffset() throws IOException { + //noinspection ConstantConditions Review comment: Not a big fan of leaving inspection settings in code. If everyone does it with different IDEs/settings, it will become quickly a mess. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org With regards, Apache Git Services
