spark coalesce-public 源码
spark coalesce-public 代码
文件路径：/core/src/main/scala/org/apache/spark/rdd/coalesce-public.scala
/*
* 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.rdd
import scala.collection.mutable
import org.apache.spark.Partition
import org.apache.spark.annotation.DeveloperApi
/**
* ::DeveloperApi::
* A PartitionCoalescer defines how to coalesce the partitions of a given RDD.
*/
@DeveloperApi
trait PartitionCoalescer {
/**
* Coalesce the partitions of the given RDD.
*
* @param maxPartitions the maximum number of partitions to have after coalescing
* @param parent the parent RDD whose partitions to coalesce
* @return an array of [[PartitionGroup]]s, where each element is itself an array of
* `Partition`s and represents a partition after coalescing is performed.
*/
def coalesce(maxPartitions: Int, parent: RDD[_]): Array[PartitionGroup]
}
/**
* ::DeveloperApi::
* A group of `Partition`s
* @param prefLoc preferred location for the partition group
*/
@DeveloperApi
class PartitionGroup(val prefLoc: Option[String] = None) {
val partitions = mutable.ArrayBuffer[Partition]()
def numPartitions: Int = partitions.size
}
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