JBR-8664 Optimize sun.nio.fs.WindowsPath.compareTo

src/java.base/unix/classes/sun/nio/fs/UnixPath.java

@@ -37,6 +37,7 @@ import java.nio.file.WatchEvent;
 import java.nio.file.WatchKey;
 import java.nio.file.WatchService;
 import java.nio.file.spi.FileSystemProvider;
+import java.util.Arrays;
 import java.util.Objects;
 
 import jdk.internal.access.JavaLangAccess;
@@ -718,23 +719,7 @@ class UnixPath implements Path {
 
     @Override
     public int compareTo(Path other) {
-        int len1 = path.length;
-        int len2 = ((UnixPath) other).path.length;
-
-        int n = Math.min(len1, len2);
-        byte v1[] = path;
-        byte v2[] = ((UnixPath) other).path;
-
-        int k = 0;
-        while (k < n) {
-            int c1 = v1[k] & 0xff;
-            int c2 = v2[k] & 0xff;
-            if (c1 != c2) {
-                return c1 - c2;
-            }
-           k++;
-        }
-        return len1 - len2;
+        return Arrays.compareUnsigned(path, ((UnixPath) other).path);
     }
 
     @Override

src/java.base/windows/classes/sun/nio/fs/WindowsPath.java

@@ -64,6 +64,9 @@ class WindowsPath implements Path {
     // paths and has a long path prefix for all paths longer than MAX_PATH.
     private volatile WeakReference<String> pathForWin32Calls;
 
+    // Used for fast string comparison.
+    private volatile WeakReference<byte[]> uppercasePath;
+
     // offsets into name components (computed lazily)
     private volatile Integer[] offsets;
 
@@ -786,28 +789,12 @@ class WindowsPath implements Path {
         }
         return true;
     }
-
+    
     @Override
     public int compareTo(Path obj) {
         if (obj == null)
             throw new NullPointerException();
-        String s1 = path;
-        String s2 = ((WindowsPath)obj).path;
-        int n1 = s1.length();
-        int n2 = s2.length();
-        int min = Math.min(n1, n2);
-        for (int i = 0; i < min; i++) {
-            char c1 = s1.charAt(i);
-            char c2 = s2.charAt(i);
-             if (c1 != c2) {
-                 c1 = Character.toUpperCase(c1);
-                 c2 = Character.toUpperCase(c2);
-                 if (c1 != c2) {
-                     return c1 - c2;
-                 }
-             }
-        }
-        return n1 - n2;
+        return Arrays.compareUnsigned(getUppercasePath(), ((WindowsPath)obj).getUppercasePath());
     }
 
     @Override
@@ -893,6 +880,15 @@ class WindowsPath implements Path {
         }
     }
 
+    private byte[] getUppercasePath() {
+        byte[] result = uppercasePath.get();
+        if (result == null) {
+            result = path.toUpperCase().getBytes();
+            uppercasePath = new WeakReference<>(result);
+        }
+        return result;
+    }
+
     void checkRead() {
         @SuppressWarnings("removal")
         SecurityManager sm = System.getSecurityManager();