spark PrimitiveVector 源码
spark PrimitiveVector 代码
文件路径：/core/src/main/scala/org/apache/spark/util/collection/PrimitiveVector.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.collection
import scala.reflect.ClassTag
/**
* An append-only, non-threadsafe, array-backed vector that is optimized for primitive types.
*/
private[spark]
class PrimitiveVector[@specialized(Long, Int, Double) V: ClassTag](initialSize: Int = 64) {
private var _numElements = 0
private var _array: Array[V] = _
// NB: This must be separate from the declaration, otherwise the specialized parent class
// will get its own array with the same initial size.
_array = new Array[V](initialSize)
def apply(index: Int): V = {
require(index < _numElements)
_array(index)
}
def +=(value: V): Unit = {
if (_numElements == _array.length) {
resize(_array.length * 2)
}
_array(_numElements) = value
_numElements += 1
}
def capacity: Int = _array.length
def length: Int = _numElements
def size: Int = _numElements
def iterator: Iterator[V] = new Iterator[V] {
var index = 0
override def hasNext: Boolean = index < _numElements
override def next(): V = {
if (!hasNext) {
throw new NoSuchElementException
}
val value = _array(index)
index += 1
value
}
}
/** Gets the underlying array backing this vector. */
def array: Array[V] = _array
/** Trims this vector so that the capacity is equal to the size. */
def trim(): PrimitiveVector[V] = resize(size)
/** Resizes the array, dropping elements if the total length decreases. */
def resize(newLength: Int): PrimitiveVector[V] = {
_array = copyArrayWithLength(newLength)
if (newLength < _numElements) {
_numElements = newLength
}
this
}
/** Return a trimmed version of the underlying array. */
def toArray: Array[V] = {
copyArrayWithLength(size)
}
private def copyArrayWithLength(length: Int): Array[V] = {
val copy = new Array[V](length)
_array.copyToArray(copy)
copy
}
}
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