Github user brkyvz commented on a diff in the pull request: https://github.com/apache/spark/pull/18199#discussion_r120219455 --- Diff: sql/core/src/main/scala/org/apache/spark/sql/execution/streaming/RateSourceProvider.scala --- @@ -0,0 +1,240 @@ +/* + * 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.execution.streaming + +import java.io._ +import java.nio.charset.StandardCharsets +import java.util.concurrent.TimeUnit + +import org.apache.commons.io.IOUtils + +import org.apache.spark.internal.Logging +import org.apache.spark.network.util.JavaUtils +import org.apache.spark.sql.{DataFrame, SQLContext} +import org.apache.spark.sql.catalyst.InternalRow +import org.apache.spark.sql.catalyst.util.{CaseInsensitiveMap, DateTimeUtils} +import org.apache.spark.sql.sources.{DataSourceRegister, StreamSourceProvider} +import org.apache.spark.sql.types._ +import org.apache.spark.util.{ManualClock, SystemClock} + +/** + * A source that generates increment long values with timestamps. Each generated row has two + * columns: a timestamp column for the generated time and an auto increment long column starting + * with 0L. + * + * This source supports the following options: + * - `tuplesPerSecond` (e.g. 100, default: 1): How many tuples should be generated per second. + * - `rampUpTime` (e.g. 5s, default: 0s): How long to ramp up before the generating speed + * becomes `tuplesPerSecond`. Using finer granularities than seconds will be truncated to integer + * seconds. + * - `numPartitions` (e.g. 10, default: Spark's default parallelism): The partition number for the + * generated tuples. The source will try its best to reach `tuplesPerSecond`, but the query may + * be resource constrained, and `numPartitions` can be tweaked to help reach the desired speed. + */ +class RateSourceProvider extends StreamSourceProvider with DataSourceRegister { + + override def sourceSchema( + sqlContext: SQLContext, + schema: Option[StructType], + providerName: String, + parameters: Map[String, String]): (String, StructType) = + (shortName(), RateSourceProvider.SCHEMA) + + override def createSource( + sqlContext: SQLContext, + metadataPath: String, + schema: Option[StructType], + providerName: String, + parameters: Map[String, String]): Source = { + val params = CaseInsensitiveMap(parameters) + + val tuplesPerSecond = params.get("tuplesPerSecond").map(_.toLong).getOrElse(1L) + if (tuplesPerSecond <= 0) { + throw new IllegalArgumentException( + s"Invalid value '${params("tuplesPerSecond")}'. The option 'tuplesPerSecond' " + + "must be positive") + } + + val rampUpTimeSeconds = + params.get("rampUpTime").map(JavaUtils.timeStringAsSec(_)).getOrElse(0L) + if (rampUpTimeSeconds < 0) { + throw new IllegalArgumentException( + s"Invalid value '${params("rampUpTime")}'. The option 'rampUpTime' " + + "must not be negative") + } + + val numPartitions = params.get("numPartitions").map(_.toInt).getOrElse( + sqlContext.sparkContext.defaultParallelism) + if (numPartitions <= 0) { + throw new IllegalArgumentException( + s"Invalid value '${params("numPartitions")}'. The option 'numPartitions' " + + "must be positive") + } + + new RateStreamSource( + sqlContext, + metadataPath, + tuplesPerSecond, + rampUpTimeSeconds, + numPartitions, + params.get("useManualClock").map(_.toBoolean).getOrElse(false) // Only for testing + ) + } + override def shortName(): String = "rate" +} + +object RateSourceProvider { + val SCHEMA = + StructType(StructField("timestamp", TimestampType) :: StructField("value", LongType) :: Nil) + + val VERSION = 1 +} + +class RateStreamSource( + sqlContext: SQLContext, + metadataPath: String, + tuplesPerSecond: Long, + rampUpTimeSeconds: Long, + numPartitions: Int, + useManualClock: Boolean) extends Source with Logging { + + import RateSourceProvider._ + import RateStreamSource._ + + val clock = if (useManualClock) new ManualClock else new SystemClock + + private val maxSeconds = Long.MaxValue / tuplesPerSecond + + if (rampUpTimeSeconds > maxSeconds) { + throw new ArithmeticException( + s"Integer overflow. Max offset with $tuplesPerSecond tuplesPerSecond" + + s" is $maxSeconds, but 'rampUpTimeSeconds' is $rampUpTimeSeconds.") + } + + private val startTimeMs = { + val metadataLog = + new HDFSMetadataLog[LongOffset](sqlContext.sparkSession, metadataPath) { + override def serialize(metadata: LongOffset, out: OutputStream): Unit = { + val writer = new BufferedWriter(new OutputStreamWriter(out, StandardCharsets.UTF_8)) + writer.write("v" + VERSION + "\n") + writer.write(metadata.json) + writer.flush + } + + override def deserialize(in: InputStream): LongOffset = { + val content = IOUtils.toString(new InputStreamReader(in, StandardCharsets.UTF_8)) + // HDFSMetadataLog guarantees that it never creates a partial file. + assert(content.length != 0) + if (content(0) == 'v') { + val indexOfNewLine = content.indexOf("\n") + if (indexOfNewLine > 0) { + val version = parseVersion(content.substring(0, indexOfNewLine), VERSION) + LongOffset(SerializedOffset(content.substring(indexOfNewLine + 1))) + } else { + throw new IllegalStateException( + s"Log file was malformed: failed to detect the log file version line.") + } + } else { + throw new IllegalStateException( + s"Log file was malformed: failed to detect the log file version line.") + } + } + } + + metadataLog.get(0).getOrElse { + val offset = LongOffset(clock.getTimeMillis()) + metadataLog.add(0, offset) + logInfo(s"Start time: $offset") + offset + }.offset + } + + /** When the system time runs backward, "lastTimeMs" will make sure we are still monotonic. */ + @volatile private var lastTimeMs = startTimeMs + + override def schema: StructType = RateSourceProvider.SCHEMA + + override def getOffset: Option[Offset] = { + val now = clock.getTimeMillis() + if (lastTimeMs < now) { + lastTimeMs = now + } + Some(LongOffset(TimeUnit.MILLISECONDS.toSeconds(lastTimeMs - startTimeMs))) + } + + override def getBatch(start: Option[Offset], end: Offset): DataFrame = { + val startSeconds = start.flatMap(LongOffset.convert(_).map(_.offset)).getOrElse(0L) + val endSeconds = LongOffset.convert(end).map(_.offset).getOrElse(0L) + assert(startSeconds <= endSeconds, s"startSeconds($startSeconds) > endSeconds($endSeconds)") + if (endSeconds > maxSeconds) { + throw new ArithmeticException("Integer overflow. Max offset with " + + s"$tuplesPerSecond tuplesPerSecond is $maxSeconds, but it's $endSeconds now.") + } + // Fix "lastTimeMs" for recovery + if (lastTimeMs < TimeUnit.SECONDS.toMillis(endSeconds) + startTimeMs) { + lastTimeMs = TimeUnit.SECONDS.toMillis(endSeconds) + startTimeMs + } + val rangeStart = valueAtSecond(startSeconds, tuplesPerSecond, rampUpTimeSeconds) + val rangeEnd = valueAtSecond(endSeconds, tuplesPerSecond, rampUpTimeSeconds) + logDebug(s"startSeconds: $startSeconds, endSeconds: $endSeconds, " + + s"rangeStart: $rangeStart, rangeEnd: $rangeEnd") + + if (rangeStart == rangeEnd) { + return sqlContext.internalCreateDataFrame(sqlContext.sparkContext.emptyRDD, schema) + } + + val localStartTimeMs = startTimeMs + TimeUnit.SECONDS.toMillis(startSeconds) + val relativeMsPerValue = + TimeUnit.SECONDS.toMillis(endSeconds - startSeconds) / (rangeEnd - rangeStart) --- End diff -- integer division bug! This can easily return 0 right?
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