vanzin commented on a change in pull request #25007: [SPARK-28209][CORE][SHUFFLE] Proposed new shuffle writer API URL: https://github.com/apache/spark/pull/25007#discussion_r307068612
########## File path: core/src/main/java/org/apache/spark/shuffle/api/TransferrableWritableByteChannel.java ########## @@ -0,0 +1,59 @@ +/* + * 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.spark.shuffle.api; + +import java.io.Closeable; +import java.io.IOException; + +import java.nio.channels.FileChannel; +import java.nio.channels.WritableByteChannel; +import org.apache.spark.annotation.Private; + +/** + * :: Private :: + * Represents an output byte channel that can copy bytes from input file channels to some + * arbitrary storage system. + * <p> + * This API is provided for advanced users who can transfer bytes from a file channel to + * some output sink without copying data into memory. Most users should not need to use + * this functionality; this is primarily provided for the built-in shuffle storage backends + * that persist shuffle files on local disk. + * <p> + * For a simpler alternative, see {@link ShufflePartitionWriter}. + * + * @since 3.0.0 + */ +@Private +public interface TransferrableWritableByteChannel extends Closeable { + + /** + * Copy all bytes from the source readable byte channel into this byte channel. + * <p> + * This method should block until all of the bytes from the source (that is, up until + * numBytesToTransfer) are available in the output storage layer. + * + * @param source File to transfer bytes from. Do not call anything on this channel other than Review comment: Commenting here to keep context, even though this code doesn't exist anymore. I see you implemented basically my first suggestion. I think that if you instead make `ShufflePartitionWriter` implement `Closeable`, you can achieve the same goal with less things for people to implement. (`openChannel()` would just return a `WritableByteChannel`, and `close()` would close whatever was opened by either `open` call.) It could even simplify some code in `BypassMergeSortShuffleWriter` since now the `close()` call would be the same regardless of whether it's a stream or a channel. But that's minor now, and I'm just trying to reduce the amount of code needed for this optimization to work. Current version seems fine otherwise. ---------------------------------------------------------------- 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 --------------------------------------------------------------------- To unsubscribe, e-mail: reviews-unsubscr...@spark.apache.org For additional commands, e-mail: reviews-h...@spark.apache.org