asl3 commented on code in PR #53625: URL: https://github.com/apache/spark/pull/53625#discussion_r2654775700
########## common/utils-java/src/main/java/org/apache/spark/util/UUIDv7Generator.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.spark.util; + +import java.util.UUID; +import java.util.concurrent.ThreadLocalRandom; +import java.util.concurrent.atomic.AtomicLong; + +/** + * Generator for UUIDv7 as defined in RFC 9562. + * https://www.rfc-editor.org/rfc/rfc9562.html + * + * UUIDv7 is a time-ordered UUID that embeds a Unix timestamp in milliseconds. + * + * The generate() method guarantees monotonicity by tracking the last used timestamp + * and increments if necessary when the clock hasn't advanced. Review Comment: Thanks for the inputs. Considering the trade-offs, I updated to not enforce strict monotonicity in this implementation (and document the limitation) to avoid degrading throughput. JDK26 also does not guarantee monotonicity, but places the responsibility on the caller to provide monotonic timestamps if strict ordering is required. For Spark `queryId` use case, millisecond-level ordering should be sufficient. If we later need strict monotonicity for specific use cases we could add a separate `generateMonotonic()`. -- 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: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
