spark LongArray 源码
spark LongArray 代码
文件路径：/common/unsafe/src/main/java/org/apache/spark/unsafe/array/LongArray.java
/*
* 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.unsafe.array;
import org.apache.spark.unsafe.Platform;
import org.apache.spark.unsafe.memory.MemoryBlock;
/**
* An array of long values. Compared with native JVM arrays, this:
* <ul>
* <li>supports using both on-heap and off-heap memory</li>
* <li>has no bound checking, and thus can crash the JVM process when assert is turned off</li>
* </ul>
*/
public final class LongArray {
// This is a long so that we perform long multiplications when computing offsets.
private static final long WIDTH = 8;
private final MemoryBlock memory;
private final Object baseObj;
private final long baseOffset;
private final long length;
public LongArray(MemoryBlock memory) {
assert memory.size() < (long) Integer.MAX_VALUE * 8: "Array size >= Integer.MAX_VALUE elements";
this.memory = memory;
this.baseObj = memory.getBaseObject();
this.baseOffset = memory.getBaseOffset();
this.length = memory.size() / WIDTH;
}
public MemoryBlock memoryBlock() {
return memory;
}
public Object getBaseObject() {
return baseObj;
}
public long getBaseOffset() {
return baseOffset;
}
/**
* Returns the number of elements this array can hold.
*/
public long size() {
return length;
}
/**
* Fill this all with 0L.
*/
public void zeroOut() {
for (long off = baseOffset; off < baseOffset + length * WIDTH; off += WIDTH) {
Platform.putLong(baseObj, off, 0);
}
}
/**
* Sets the value at position {@code index}.
*/
public void set(int index, long value) {
assert index >= 0 : "index (" + index + ") should >= 0";
assert index < length : "index (" + index + ") should < length (" + length + ")";
Platform.putLong(baseObj, baseOffset + index * WIDTH, value);
}
/**
* Returns the value at position {@code index}.
*/
public long get(int index) {
assert index >= 0 : "index (" + index + ") should >= 0";
assert index < length : "index (" + index + ") should < length (" + length + ")";
return Platform.getLong(baseObj, baseOffset + index * WIDTH);
}
}
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