cloud-fan commented on a change in pull request #31905: URL: https://github.com/apache/spark/pull/31905#discussion_r655406702
########## File path: sql/core/src/main/scala/org/apache/spark/sql/Observation.scala ########## @@ -0,0 +1,170 @@ +/* + * 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.sql + +import java.util.UUID +import java.util.concurrent.TimeUnit + +import org.apache.spark.sql.execution.QueryExecution +import org.apache.spark.sql.util.QueryExecutionListener + +/** + * Helper class to simplify usage of [[Dataset.observe(String, Column, Column*)]]: + * + * {{{ + * // Observe row count (rows) and highest id (maxid) in the Dataset while writing it + * val observation = Observation("my_metrics") + * val observed_ds = ds.observe(observation, count(lit(1)).as("rows"), max($"id").as("maxid")) + * observed_ds.write.parquet("ds.parquet") + * val metrics = observation.get + * }}} + * + * This collects the metrics while the first action is executed on the obseerved dataset. Subsequent + * actions do not modify the metrics returned by [[org.apache.spark.sql.Observation.get]]. Retrieval + * of the metric via [[org.apache.spark.sql.Observation.get]] blocks until the first action has + * finished and metrics become available. You can add a timeout to that blocking via + * [[org.apache.spark.sql.Observation.waitCompleted]]: + * + * {{{ + * if (observation.waitCompleted(100, TimeUnit.MILLISECONDS)) { + * observation.get + * } + * }}} + * + * This class does not support streaming datasets. + * + * @param name name of the metric + * @since 3.2.0 + */ +class Observation(name: String) { + + private val listener: ObservationListener = ObservationListener(this) + + private var sparkSession: Option[SparkSession] = None + + @volatile private var row: Option[Row] = None + + /** + * Attaches this observation to the given [[Dataset]] to observe aggregation expressions. + * + * @param ds dataset + * @param expr first aggregation expression + * @param exprs more aggregation expressions + * @tparam T dataset type + * @return observed dataset + * @throws IllegalArgumentException If this is a streaming Dataset (ds.isStreaming == true) + */ + def on[T](ds: Dataset[T], expr: Column, exprs: Column*): Dataset[T] = { + if (ds.isStreaming) { + throw new IllegalArgumentException("Observation does not support streaming Datasets") + } + register(ds.sparkSession) + ds.observe(name, expr, exprs: _*) + } + + /** + * Waits for the first action on the observed dataset to complete and returns true. + * The result is then available through the get method. + * This method times out after the given amount of time returning false. + * + * @param time timeout + * @param unit timeout time unit + * @return true if action completed within timeout, false otherwise + * @throws InterruptedException interrupted while waiting + */ + def waitCompleted(time: Long, unit: TimeUnit): Boolean = waitCompleted(Some(unit.toMillis(time))) + + /** + * Get the observed metrics. This waits until the observed dataset finishes its first action. + * If you want to wait for the result and provide a timeout, use [[waitCompleted]]. Only the + * result of the first action is available. Subsequent actions do not modify the result. + * + * @return the observed metrics as a [[Row]] + * @throws InterruptedException interrupted while waiting + */ + def get: Row = { + assert(waitCompleted(None), "waitCompleted without timeout returned false") + row.get + } + + private def waitCompleted(millis: Option[Long]): Boolean = { Review comment: Actually `Object.wait(0)` means wait forever. -- 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 --------------------------------------------------------------------- To unsubscribe, e-mail: reviews-unsubscr...@spark.apache.org For additional commands, e-mail: reviews-h...@spark.apache.org
