rkhachatryan 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_r405427372
########## File path: flink-runtime/src/main/java/org/apache/flink/runtime/checkpoint/channel/ChannelStateStreamReader.java ########## @@ -0,0 +1,111 @@ +/* + * 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.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 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}. + * Once all data is read, this class can't be used anymore. + * Uses {@link RefCountingFSDataInputStream} internally. + */ +@NotThreadSafe +class ChannelStateStreamReader implements Closeable { + + private final RefCountingFSDataInputStream stream; + private final ChannelStateDeserializer serializer; + private final Queue<Long> offsets; + private int remainingBytes = -1; + private boolean closed = false; + + ChannelStateStreamReader(AbstractChannelStateHandle<?> handle, RefCountingFSDataInputStreamFactory streamFactory) { + this(streamFactory.getOrCreate(handle), handle.getOffsets(), streamFactory.getSerializer()); + } + + private ChannelStateStreamReader(RefCountingFSDataInputStream stream, List<Long> offsets, ChannelStateDeserializer serializer) { + this.stream = stream; + this.stream.incRef(); + 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 { + closed = true; + stream.decRef(); + return NO_MORE_DATA; + } + } + + private void readWhilePossible(ChannelStateByteBuffer buffer) throws IOException { + while (haveMoreData() && buffer.isWritable()) { + if (remainingBytes <= 0) { + advanceOffset(); + } + int bytesRead = serializer.readData(stream, buffer, remainingBytes); + remainingBytes -= bytesRead; + } + } + + private boolean haveMoreData() { + return remainingBytes > 0 || !offsets.isEmpty(); + } + + @SuppressWarnings("ConstantConditions") Review comment: `SuppressWarnings` is a compiler annotation so it can be ignored by humans. Compiler warnings, on the other hand, are intended for humans and shouldn't be ignored. Therefore useless warnings produce clutter and unsupported `SuppressWarnings` not. ---------------------------------------------------------------- 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: [email protected] With regards, Apache Git Services
