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8321591: (fs) Improve String -> Path conversion performance (win)

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Reviewed-by: alanb
This commit is contained in:
Brian Burkhalter 2025-04-07 18:46:04 +00:00
parent 885cf0ff8d
commit 5481021ee6
2 changed files with 113 additions and 55 deletions
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116
src/java.base/windows/classes/sun/nio/fs/WindowsPathParser.java
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@ -1,5 +1,5 @@
/*
* Copyright (c) 2008, 2023, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2008, 2025, Oracle and/or its affiliates. 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
@ -37,38 +37,7 @@ class WindowsPathParser {
/**
* The result of a parse operation
*/
static class Result {
private final WindowsPathType type;
private final String root;
private final String path;
Result(WindowsPathType type, String root, String path) {
this.type = type;
this.root = root;
this.path = path;
}
/**
* The path type
*/
WindowsPathType type() {
return type;
}
/**
* The root component
*/
String root() {
return root;
}
/**
* The normalized path (includes root)
*/
String path() {
return path;
}
}
record Result(WindowsPathType type, String root, String path) {};
/**
* Parses the given input as a Windows path
@ -117,7 +86,7 @@ class WindowsPathParser {
char c = 0;
int next = 2;
if (isSlash(c0) && isSlash(c1)) {
// UNC: We keep the first two slash, collapse all the
// UNC: We keep the first two slashes, collapse all the
// following, then take the hostname and share name out,
// meanwhile collapsing all the redundant slashes.
type = WindowsPathType.UNC;
@ -170,9 +139,7 @@ class WindowsPathParser {
}
if (requireToNormalize) {
StringBuilder sb = new StringBuilder(input.length());
sb.append(root);
return new Result(type, root, normalize(sb, input, off));
return new Result(type, root, normalize(root, input, off));
} else {
return new Result(type, root, input);
}
@ -182,40 +149,62 @@ class WindowsPathParser {
* Remove redundant slashes from the rest of the path, forcing all slashes
* into the preferred slash.
*/
private static String normalize(StringBuilder sb, String path, int off) {
int len = path.length();
off = nextNonSlash(path, off, len);
int start = off;
private static String normalize(String root, String path, int pathOff) {
int rootLen = root.length();
int pathLen = path.length();
// the result array will initally contain the characters of root in
// the first rootLen elements followed by the chanacters of path from
// position index pathOff to the end of path
char[] result = new char[rootLen + pathLen - pathOff];
root.getChars(0, rootLen, result, 0);
path.getChars(pathOff, pathLen, result, rootLen);
// the portion of array derived from path is normalized by copying
// from position srcPos to position dstPos, and as the invariant
// dstPos <= srcPos holds, no characters can be overwritten
int dstPos = rootLen;
int srcPos = nextNonSlash(result, rootLen, result.length);
// pathPos is the position in array which is being tested as to
// whether the element at that position is a slash
int pathPos = srcPos;
char lastC = 0;
while (off < len) {
char c = path.charAt(off);
while (pathPos < result.length) {
char c = result[pathPos];
if (isSlash(c)) {
if (lastC == ' ')
throw new InvalidPathException(path,
"Trailing char <" + lastC + ">",
off - 1);
sb.append(path, start, off);
off = nextNonSlash(path, off, len);
if (off != len) //no slash at the end of normalized path
sb.append('\\');
start = off;
pathPos - 1);
int nchars = pathPos - srcPos;
System.arraycopy(result, srcPos, result, dstPos, nchars);
dstPos += nchars;
pathPos = nextNonSlash(result, pathPos, result.length);
if (pathPos != result.length) //no slash at the end of normalized path
result[dstPos++] = '\\';
srcPos = pathPos;
} else {
if (isInvalidPathChar(c))
throw new InvalidPathException(path,
"Illegal char <" + c + ">",
off);
pathPos);
lastC = c;
off++;
pathPos++;
}
}
if (start != off) {
if (srcPos != pathPos) {
if (lastC == ' ')
throw new InvalidPathException(path,
"Trailing char <" + lastC + ">",
off - 1);
sb.append(path, start, off);
pathPos - 1);
int nchars = pathPos - srcPos;
System.arraycopy(result, srcPos, result, dstPos, nchars);
dstPos += nchars;
}
return sb.toString();
return new String(result, 0, dstPos);
}
private static final boolean isSlash(char c) {
@ -227,6 +216,11 @@ class WindowsPathParser {
return off;
}
private static final int nextNonSlash(char[] path, int off, int end) {
while (off < end && isSlash(path[off])) { off++; }
return off;
}
private static final int nextSlash(String path, int off, int end) {
char c;
while (off < end && !isSlash(c=path.charAt(off))) {
@ -239,6 +233,18 @@ class WindowsPathParser {
return off;
}
private static final int nextSlash(char[] path, int off, int end) {
char c;
while (off < end && !isSlash(c=path[off])) {
if (isInvalidPathChar(c))
throw new InvalidPathException(new String(path),
"Illegal character [" + c + "] in path",
off);
off++;
}
return off;
}
private static final boolean isLetter(char c) {
return ((c >= 'a') && (c <= 'z')) || ((c >= 'A') && (c <= 'Z'));
}

52
test/micro/org/openjdk/bench/java/nio/file/PathOfString.java Normal file
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@ -0,0 +1,52 @@
/*
* Copyright (c) 2025, Oracle and/or its affiliates. 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
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package org.openjdk.bench.java.nio.file;
import java.nio.file.Path;
import org.openjdk.jmh.annotations.Benchmark;
import org.openjdk.jmh.annotations.Param;
import org.openjdk.jmh.annotations.Scope;
import org.openjdk.jmh.annotations.State;
@State(Scope.Benchmark)
public class PathOfString {
@Param({"C:\\Users\\foo\\bar\\gus.txt", // absolute
"C:\\Users\\\\foo\\\\bar\\gus.txt", // ... with extra '\\'s
"\\\\.\\UNC\\localhost\\C$\\Users\\foo", // UNC
"\\\\.\\UNC\\localhost\\C$\\\\Users\\\\foo", // ... with extra '\\'s
"\\\\?\\C:\\Users\\foo\\bar\\gus.txt", // long path prefix
"\\\\?\\C:\\Users\\\\foo\\bar\\\\gus.txt", // ... with extra '\\'s
".\\foo\\bar\\gus.txt", // relative
".\\foo\\\\bar\\\\gus.txt", // ... with extra '\\'s
"\\foo\\bar\\gus.txt", // current drive-relative
"\\foo\\\\bar\\\\gus.txt", // ... with extra '\\'s
"C:foo\\bar\\gus.txt", // drive's current directory-relative
"C:foo\\\\bar\\\\gus.txt"}) // ... with extra '\\'s
public String path;
@Benchmark
public Path parse() {
return Path.of(path);
}
}