szetszwo commented on code in PR #11412: URL: https://github.com/apache/ozone/pull/11412#discussion_r4251458769
########## hadoop-hdds/container-service/src/main/java/org/apache/hadoop/ozone/container/common/transport/server/ratis/ClosedContainerReadResolver.java: ########## @@ -0,0 +1,67 @@ +/* + * 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.hadoop.ozone.container.common.transport.server.ratis; + +import java.io.IOException; +import org.apache.hadoop.hdds.protocol.DatanodeDetails; +import org.apache.hadoop.hdds.protocol.datanode.proto.ContainerProtos.ContainerCommandRequestProto; +import org.apache.hadoop.hdds.protocol.datanode.proto.ContainerProtos.Type; +import org.apache.hadoop.hdds.ratis.ContainerCommandRequestMessage; +import org.apache.hadoop.ozone.container.common.interfaces.Container; +import org.apache.hadoop.ozone.container.common.interfaces.ContainerDispatcher; +import org.apache.hadoop.ozone.container.ozoneimpl.ContainerController; +import org.apache.ratis.protocol.RaftClientRequest; +import org.apache.ratis.server.api.DataStreamApi; + +/** + * Serves ReadBlock on a Ratis read-only data stream, without a Raft group, for a container that is not open or closing. + * SCM gives the read pipeline of such a container a random ID, and no Raft group has this ID. + * The container no longer changes through Raft, so this datanode can serve the read from its replica. + */ +final class ClosedContainerReadResolver implements DataStreamApi.Resolver { + private final ContainerDispatcher dispatcher; + private final ContainerController containerController; + private final String datanodeUuid; + + ClosedContainerReadResolver(ContainerDispatcher dispatcher, ContainerController containerController, + DatanodeDetails datanode) { + this.dispatcher = dispatcher; + this.containerController = containerController; + this.datanodeUuid = datanode.getUuidString(); + } + + /** + * @return the API to serve a ReadBlock of a container on this datanode that is not open or closing. Otherwise, null: + * Ratis then serves the request with its Raft group. + */ + @Override + public DataStreamApi resolve(RaftClientRequest request) throws IOException { + final ContainerCommandRequestProto requestProto = ContainerCommandRequestMessage.toProto( + request.getMessage().getContent(), request.getRaftGroupId()); + if (requestProto.getCmdType() != Type.ReadBlock + || requestProto.hasDatanodeUuid() && !datanodeUuid.equals(requestProto.getDatanodeUuid())) { + return null; + } + + final Container<?> container = containerController.getContainer(requestProto.getContainerID()); + if (container == null || container.getContainerData().isOpen() || container.getContainerData().isClosing()) { + return null; + } + return (message, stream) -> ContainerStateMachine.streamReadBlock(dispatcher, requestProto, stream); + } +} Review Comment: We should throw an exception: ```java @Override public DataStreamApi resolve(RaftClientRequest request) throws IOException { final ContainerCommandRequestProto requestProto = ContainerCommandRequestMessage.toProto( request.getMessage().getContent(), request.getRaftGroupId()); if (requestProto.getCmdType() != Type.ReadBlock) { throw new IOException("Non-ReadBlock command type: " + requestProto.getCmdType()); } if (requestProto.hasDatanodeUuid() && !datanodeUuid.equals(requestProto.getDatanodeUuid())) { throw new IOException("Datanode uuid mismatch: requestProto has " + requestProto.getDatanodeUuid() + " but the local datanode is " + datanodeUuid); } final Container<?> container = containerController.getContainer(requestProto.getContainerID()); if (container == null) { throw new IOException("Container not found: " + requestProto.getContainerID()); } if (container.getContainerData().getState() != ContainerProtos.ContainerDataProto.State.CLOSED) { throw new IOException("Non-CLOSED container state: " + container.getContainerData().getState()); } return (message, stream) -> ContainerStateMachine.streamReadBlock(dispatcher, requestProto, stream); } ``` ########## hadoop-hdds/container-service/src/main/java/org/apache/hadoop/ozone/container/common/transport/server/ratis/ContainerStateMachine.java: ########## @@ -892,6 +901,97 @@ public CompletableFuture<Message> query(Message request) { } } + /** Serves a Ratis read-only data stream. Only ReadBlock is supported, see {@link #streamReadBlock}. */ + @Override + public long transferTo(Message request, WritableByteChannel stream) throws IOException { + try { + metrics.incNumQueryStateMachineOps(); + final ContainerCommandRequestProto requestProto = message2ContainerCommandRequestProto(request); + if (requestProto.getCmdType() != Type.ReadBlock) { + throw new IOException("Unsupported command for a read-only data stream: " + requestProto.getCmdType()); + } + return streamReadBlock(dispatcher, requestProto, stream); + } catch (IOException e) { + metrics.incNumQueryStateMachineFails(); + throw e; + } + } + + /** + * Reads a block and writes each ReadBlock response to the stream as one reply: + * {@code [int: metadata length][metadata: the response without its data][data]}. + * Then closes the stream, which sends the terminal reply. + * If the read fails, this method throws without closing the stream. Ratis sends the failure as the terminal reply. + * + * @return the number of bytes written to the stream + */ + static long streamReadBlock(ContainerDispatcher dispatcher, ContainerCommandRequestProto request, + WritableByteChannel stream) throws IOException { + final AtomicLong bytesWritten = new AtomicLong(); + final AtomicReference<Throwable> error = new AtomicReference<>(); + final StreamObserver<ContainerCommandResponseProto> observer = new StreamObserver<ContainerCommandResponseProto>() { + @Override + public void onNext(ContainerCommandResponseProto response) { + try { + bytesWritten.addAndGet(writeReadBlockReply(stream, response)); + } catch (IOException e) { + error.set(e); + throw Status.CANCELLED.withDescription("Failed to write a ReadBlock reply").withCause(e).asRuntimeException(); + } + } + + @Override + public void onError(Throwable t) { + error.compareAndSet(null, t); + } + + @Override + public void onCompleted() { + } + }; + + try (RandomAccessFileChannel blockFile = new RandomAccessFileChannel()) { + dispatcher.streamDataReadOnly(request, observer, blockFile, null); + } catch (StatusRuntimeException e) { + error.compareAndSet(null, e); + } + if (error.get() != null) { + throw new IOException("Failed to read block " + BlockID.getFromProtobuf(request.getReadBlock().getBlockID()), + error.get()); + } + stream.close(); Review Comment: Checked the [ratis ReadStreamManagement.transfer(..)](https://github.com/apache/ratis/blob/5396d171f4d1a5513b6713d06362c6ef56ba1beb/ratis-netty/src/main/java/org/apache/ratis/netty/server/ReadStreamManagement.java#L251), should it add finally to call ReadStream.close()? -- This is an automated message from the Apache Git Service. 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