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/*
* 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
/**
* An ordered collection of offsets, used to track the progress of processing data from one or more
* [[Source]]s that are present in a streaming query. This is similar to simplified, single-instance
* vector clock that must progress linearly forward.
*/
case class CompositeOffset(offsets: Seq[Option[Offset]]) extends Offset {
/**
* Returns a negative integer, zero, or a positive integer as this object is less than, equal to,
* or greater than the specified object.
*/
override def compareTo(other: Offset): Int = other match {
case otherComposite: CompositeOffset if otherComposite.offsets.size == offsets.size =>
val comparisons = offsets.zip(otherComposite.offsets).map {
case (Some(a), Some(b)) => a compareTo b
case (None, None) => 0
case (None, _) => -1
case (_, None) => 1
}
val nonZeroSigns = comparisons.map(sign).filter(_ != 0).toSet
nonZeroSigns.size match {
case 0 => 0 // if both empty or only 0s
case 1 => nonZeroSigns.head // if there are only (0s and 1s) or (0s and -1s)
case _ => // there are both 1s and -1s
throw new IllegalArgumentException(
s"Invalid comparison between non-linear histories: $this <=> $other")
}
case _ =>
throw new IllegalArgumentException(s"Cannot compare $this <=> $other")
}
private def sign(num: Int): Int = num match {
case i if i < 0 => -1
case i if i == 0 => 0
case i if i > 0 => 1
}
/**
* Unpacks an offset into [[StreamProgress]] by associating each offset with the order list of
* sources.
*
* This method is typically used to associate a serialized offset with actual sources (which
* cannot be serialized).
*/
def toStreamProgress(sources: Seq[Source]): StreamProgress = {
assert(sources.size == offsets.size)
new StreamProgress ++ sources.zip(offsets).collect { case (s, Some(o)) => (s, o) }
}
override def toString: String =
offsets.map(_.map(_.toString).getOrElse("-")).mkString("[", ", ", "]")
}
object CompositeOffset {
/**
* Returns a [[CompositeOffset]] with a variable sequence of offsets.
* `nulls` in the sequence are converted to `None`s.
*/
def fill(offsets: Offset*): CompositeOffset = {
CompositeOffset(offsets.map(Option(_)))
}
}
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