/*
* Licensed to Elasticsearch under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch 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.elasticsearch.hadoop.util;
import org.elasticsearch.hadoop.EsHadoopIllegalArgumentException;
// taken from org.apache.lucene.util
abstract class ArrayUtils {
static byte[] grow(byte[] array, int minSize) {
assert minSize >= 0 : "size must be positive (got " + minSize + "): likely integer overflow?";
if (array.length < minSize) {
byte[] newArray = new byte[oversize(minSize, 1)];
System.arraycopy(array, 0, newArray, 0, array.length);
return newArray;
}
else
return array;
}
static int oversize(int minTargetSize, int bytesPerElement) {
if (minTargetSize < 0) {
// catch usage that accidentally overflows int
throw new EsHadoopIllegalArgumentException("invalid array size " + minTargetSize);
}
if (minTargetSize == 0) {
// wait until at least one element is requested
return 0;
}
// asymptotic exponential growth by 1/8th, favors
// spending a bit more CPU to not tie up too much wasted
// RAM:
int extra = minTargetSize >> 3;
if (extra < 3) {
// for very small arrays, where constant overhead of
// realloc is presumably relatively high, we grow
// faster
extra = 3;
}
int newSize = minTargetSize + extra;
// add 7 to allow for worst case byte alignment addition below:
if (newSize + 7 < 0) {
// int overflowed -- return max allowed array size
return Integer.MAX_VALUE;
}
if (Constants.JRE_IS_64BIT) {
// round up to 8 byte alignment in 64bit env
switch (bytesPerElement) {
case 4:
// round up to multiple of 2
return (newSize + 1) & 0x7ffffffe;
case 2:
// round up to multiple of 4
return (newSize + 3) & 0x7ffffffc;
case 1:
// round up to multiple of 8
return (newSize + 7) & 0x7ffffff8;
case 8:
// no rounding
default:
// odd (invalid?) size
return newSize;
}
}
else {
// round up to 4 byte alignment in 64bit env
switch (bytesPerElement) {
case 2:
// round up to multiple of 2
return (newSize + 1) & 0x7ffffffe;
case 1:
// round up to multiple of 4
return (newSize + 3) & 0x7ffffffc;
case 4:
case 8:
// no rounding
default:
// odd (invalid?) size
return newSize;
}
}
}
}