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8355177: Speed up StringBuilder::append(char[]) via Unsafe::copyMemory

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Reviewed-by: rriggs, rgiulietti
This commit is contained in:
Shaojin Wen 2025-07-30 13:16:27 +00:00
parent 16da81eb43
commit e2feff8599
2 changed files with 34 additions and 8 deletions
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15
src/java.base/share/classes/java/lang/StringUTF16.java
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@ -1,5 +1,6 @@
/*
* Copyright (c) 2015, 2025, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2025, Alibaba Group Holding Limited. All Rights Reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@ -1312,12 +1313,6 @@ final class StringUTF16 {
return StreamSupport.stream(LinesSpliterator.spliterator(value), false);
}
private static void putChars(byte[] val, int index, char[] str, int off, int end) {
while (off < end) {
putChar(val, index++, str[off++]);
}
}
public static String newString(byte[] val, int index, int len) {
if (len == 0) {
return "";
@ -1486,7 +1481,13 @@ final class StringUTF16 {
public static void putCharsSB(byte[] val, int index, char[] ca, int off, int end) {
checkBoundsBeginEnd(index, index + end - off, val);
putChars(val, index, ca, off, end);
String.checkBoundsBeginEnd(off, end, ca.length);
Unsafe.getUnsafe().copyMemory(
ca,
Unsafe.ARRAY_CHAR_BASE_OFFSET + ((long) off << 1),
val,
Unsafe.ARRAY_BYTE_BASE_OFFSET + ((long) index << 1),
(long) (end - off) << 1);
}
public static void putCharsSB(byte[] val, int index, CharSequence s, int off, int end) {

27
test/micro/org/openjdk/bench/java/lang/StringBuilders.java
View File

@ -1,5 +1,6 @@
/*
* Copyright (c) 2014, 2024, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2014, 2025, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2025, Alibaba Group Holding Limited. All Rights Reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@ -50,6 +51,7 @@ public class StringBuilders {
private String[] str16p8p7;
private String[] str3p9p8;
private String[] str22p40p31;
private char[][] charArray22p40p31;
private StringBuilder sbLatin1;
private StringBuilder sbLatin2;
private StringBuilder sbUtf16;
@ -63,10 +65,15 @@ public class StringBuilders {
"advise", "you", "to", "drive", "at", "top", "speed", "it'll",
"be", "a", "god", "damn", "miracle", "if", "we", "can", "get",
"there", "before", "you", "turn", "into", "a", "wild", "animal."};
str3p4p2 = new String[]{"123", "1234", "12"};
str16p8p7 = new String[]{"1234567890123456", "12345678", "1234567"};
str3p9p8 = new String[]{"123", "123456789", "12345678"};
str22p40p31 = new String[]{"1234567890123456789012", "1234567890123456789012345678901234567890", "1234567890123456789012345678901"};
charArray22p40p31 = new char[str22p40p31.length][];
for (int i = 0; i < str22p40p31.length; i++) {
charArray22p40p31[i] = str22p40p31[i].toCharArray();
}
sbLatin1 = new StringBuilder("Latin1 string");
sbLatin2 = new StringBuilder("Latin1 string");
sbUtf16 = new StringBuilder("UTF-\uFF11\uFF16 string");
@ -273,6 +280,24 @@ public class StringBuilders {
return buf.length();
}
@Benchmark
public int appendWithCharArrayLatin1() {
StringBuilder buf = new StringBuilder();
for (char[] charArray : charArray22p40p31) {
buf.append(charArray);
}
return buf.length();
}
@Benchmark
public int appendWithCharArrayUTF16() {
StringBuilder buf = new StringBuilder("\uFF11");
for (char[] charArray : charArray22p40p31) {
buf.append(charArray);
}
return buf.length();
}
@Benchmark
public String toStringCharWithBool8() {
StringBuilder result = new StringBuilder();