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/*
* Copyright (C) 2011 The Guava Authors
*
* Licensed 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 com.google.common.base;
import com.google.caliper.Param;
import com.google.caliper.Runner;
import com.google.caliper.SimpleBenchmark;
import com.google.common.base.Strings;
/**
* Microbenchmark for {@link Strings#repeat}
*
* @author Mike Cripps
*/
public class StringsRepeatBenchmark extends SimpleBenchmark {
@Param({"1", "5", "25", "125"}) int count;
@Param({"1", "10"}) int length;
private String originalString;
@Override protected void setUp() {
originalString = Strings.repeat("x", length);
}
public void timeOldRepeat(int reps) {
for (int i = 0; i < reps; i++) {
String x = oldRepeat(originalString, count);
if (x.length() != (originalString.length() * count)) {
throw new RuntimeException("Wrong length: "+x);
}
}
}
public void timeMikeRepeat(int reps) {
for (int i = 0; i < reps; i++) {
String x = mikeRepeat(originalString, count);
if (x.length() != (originalString.length() * count)) {
throw new RuntimeException("Wrong length: "+x);
}
}
}
public void timeMartinRepeat(int reps) {
for (int i = 0; i < reps; i++) {
String x = martinRepeat(originalString, count);
if (x.length() != (originalString.length() * count)) {
throw new RuntimeException("Wrong length: "+x);
}
}
}
private static final String mikeRepeat(String string, int count) {
final int len = string.length();
char[] strCopy = new char[len * Integer.highestOneBit(count)];
string.getChars(0, len, strCopy, 0);
char[] array = new char[len * count];
int strCopyLen = len;
int pos = 0;
while (count != 0) {
if ((count & 1) != 0) {
System.arraycopy(strCopy, 0, array, pos,strCopyLen);
pos += strCopyLen;
}
count >>= 1;
if (count != 0) {
System.arraycopy(strCopy, 0, strCopy, strCopyLen, strCopyLen);
strCopyLen <<= 1;
}
}
return new String(array);
}
private static final String oldRepeat(String string, int count) {
// If this multiplication overflows, a NegativeArraySizeException or
// OutOfMemoryError is not far behind
final int len = string.length();
final int size = len * count;
char[] array = new char[size];
for (int i = 0; i < size; i+=len) {
string.getChars(0, len, array, i);
}
return new String(array);
}
private static final String martinRepeat(String string, int count) {
final int len = string.length();
final int size = len * count;
final char[] array = new char[size];
string.getChars(0, len, array, 0);
int n;
for (n = len; n < size - n; n <<= 1) {
System.arraycopy(array, 0, array, n, n);
}
System.arraycopy(array, 0, array, n, size - n);
return new String(array);
}
public static void main(String[] args) {
Runner.main(StringsRepeatBenchmark.class, args);
}
}
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