spark Iterators 源码
spark Iterators 代码
文件路径：/core/src/main/scala-2.13/org/apache/spark/util/Iterators.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.util
object Iterators {
/**
* Counts the number of elements of an iterator.
* This method is slower than `iterator.size` when using Scala 2.13,
* but it can avoid overflowing problem.
*/
def size(iterator: Iterator[_]): Long = {
// SPARK-39928: For Scala 2.13, add check of `iterator.knownSize` refer to
// `IterableOnceOps#size` to reduce the performance gap with `iterator.size`.
if (iterator.knownSize > 0) iterator.knownSize.toLong
else {
var count = 0L
while (iterator.hasNext) {
count += 1L
iterator.next()
}
count
}
}
}
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