attilapiros commented on code in PR #50230: URL: https://github.com/apache/spark/pull/50230#discussion_r2070893252
########## core/src/main/java/org/apache/spark/shuffle/checksum/RowBasedChecksum.scala: ########## @@ -0,0 +1,114 @@ +/* + * 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.checksum + +import java.io.ObjectOutputStream +import java.util.zip.Checksum + +import scala.util.control.NonFatal + +import org.apache.spark.internal.Logging +import org.apache.spark.network.shuffle.checksum.ShuffleChecksumHelper +import org.apache.spark.util.MyByteArrayOutputStream + +/** + * A class for computing checksum for input (key, value) pairs. The checksum is independent of + * the order of the input (key, value) pairs. It is done by computing a checksum for each row + * first, and then computing the XOR for all the row checksums. + */ +abstract class RowBasedChecksum() extends Serializable with Logging { + private var hasError: Boolean = false + private var checksumValue: Long = 0 + /** Returns the checksum value computed. Tt returns the default checksum value (0) if there + * are any errors encountered during the checksum computation. + */ + def getValue: Long = { + if (!hasError) checksumValue else 0 + } + + /** Updates the row-based checksum with the given (key, value) pair */ + def update(key: Any, value: Any): Unit = { + if (!hasError) { + try { + val rowChecksumValue = calculateRowChecksum(key, value) + checksumValue = checksumValue ^ rowChecksumValue Review Comment: I think this is a good point but hard to compute as this will be a bit more stateful. An interesting corner case when we have multiples of two different key value pairs. Then we cannot detect differences in those if it is different in the repetition meanwhile they are still odd or even, like ``` N times of ("key1", "value1") M times of ("key2", "value2") ``` cannot be distinguished from for every N>=1 and M>=1 from: ``` K times of ("key1", "value1") L times of ("key2", "value2") ``` for every K>=1 and L>=1 and K%2 = N%2 and M%2 = L%2 (meanwhile N+M can be even equal with K+L). Is not it? -- 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. To unsubscribe, e-mail: reviews-unsubscr...@spark.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: reviews-unsubscr...@spark.apache.org For additional commands, e-mail: reviews-h...@spark.apache.org
