8196334: Optimize UUID#fromString

Co-authored-by: Andriy Plokhotnyuk <plokhotnyuk@gmail.com>
Co-authored-by: Jon Chambers <jon.chambers@gmail.com>
Reviewed-by: igerasim, alanb

src/java.base/share/classes/java/util/UUID.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2003, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2003, 2020, 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
@@ -180,6 +180,45 @@ public final class UUID implements java.io.Serializable, Comparable<UUID> {
         return new UUID(md5Bytes);
     }
 
+    private static final byte[] NIBBLES;
+    static {
+        byte[] ns = new byte[256];
+        Arrays.fill(ns, (byte) -1);
+        ns['0'] = 0;
+        ns['1'] = 1;
+        ns['2'] = 2;
+        ns['3'] = 3;
+        ns['4'] = 4;
+        ns['5'] = 5;
+        ns['6'] = 6;
+        ns['7'] = 7;
+        ns['8'] = 8;
+        ns['9'] = 9;
+        ns['A'] = 10;
+        ns['B'] = 11;
+        ns['C'] = 12;
+        ns['D'] = 13;
+        ns['E'] = 14;
+        ns['F'] = 15;
+        ns['a'] = 10;
+        ns['b'] = 11;
+        ns['c'] = 12;
+        ns['d'] = 13;
+        ns['e'] = 14;
+        ns['f'] = 15;
+        NIBBLES = ns;
+    }
+
+    private static long parse4Nibbles(String name, int pos) {
+        byte[] ns = NIBBLES;
+        char ch1 = name.charAt(pos);
+        char ch2 = name.charAt(pos + 1);
+        char ch3 = name.charAt(pos + 2);
+        char ch4 = name.charAt(pos + 3);
+        return (ch1 | ch2 | ch3 | ch4) > 0xff ?
+                -1 : ns[ch1] << 12 | ns[ch2] << 8 | ns[ch3] << 4 | ns[ch4];
+    }
+
     /**
      * Creates a {@code UUID} from the string standard representation as
      * described in the {@link #toString} method.
@@ -195,6 +234,31 @@ public final class UUID implements java.io.Serializable, Comparable<UUID> {
      *
      */
     public static UUID fromString(String name) {
+        if (name.length() == 36) {
+            char ch1 = name.charAt(8);
+            char ch2 = name.charAt(13);
+            char ch3 = name.charAt(18);
+            char ch4 = name.charAt(23);
+            if (ch1 == '-' && ch2 == '-' && ch3 == '-' && ch4 == '-') {
+                long msb1 = parse4Nibbles(name, 0);
+                long msb2 = parse4Nibbles(name, 4);
+                long msb3 = parse4Nibbles(name, 9);
+                long msb4 = parse4Nibbles(name, 14);
+                long lsb1 = parse4Nibbles(name, 19);
+                long lsb2 = parse4Nibbles(name, 24);
+                long lsb3 = parse4Nibbles(name, 28);
+                long lsb4 = parse4Nibbles(name, 32);
+                if ((msb1 | msb2 | msb3 | msb4 | lsb1 | lsb2 | lsb3 | lsb4) >= 0) {
+                    return new UUID(
+                            msb1 << 48 | msb2 << 32 | msb3 << 16 | msb4,
+                            lsb1 << 48 | lsb2 << 32 | lsb3 << 16 | lsb4);
+                }
+            }
+        }
+        return fromString1(name);
+    }
+
+    private static UUID fromString1(String name) {
         int len = name.length();
         if (len > 36) {
             throw new IllegalArgumentException("UUID string too large");

test/jdk/java/util/UUID/UUIDTest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2003, 2012, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2003, 2020, 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
@@ -22,7 +22,7 @@
  */
 
 /* @test
- * @bug 4173528 5068772 8148936
+ * @bug 4173528 5068772 8148936 8196334
  * @summary Unit tests for java.util.UUID
  * @key randomness
  * @run main/othervm -XX:+CompactStrings UUIDTest
@@ -95,8 +95,9 @@ public class UUIDTest {
     private static void stringTest() throws Exception {
         for (int i=0; i<100; i++) {
             UUID u1 = UUID.randomUUID();
-            UUID u2 = UUID.fromString(u1.toString());
+            UUID u2 = UUID.fromString(u1.toString().toLowerCase());
-            if (!u1.equals(u2))
+            UUID u3 = UUID.fromString(u1.toString().toUpperCase());
+            if (!u1.equals(u2) || !u1.equals(u3))
                 throw new Exception("UUID -> string -> UUID failed");
         }
 

test/micro/org/openjdk/bench/java/util/UUIDBench.java

@@ -0,0 +1,75 @@
+/*
+ * Copyright (c) 2020, 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.util;
+
+import java.util.UUID;
+import java.util.concurrent.TimeUnit;
+
+import org.openjdk.jmh.annotations.*;
+
+@State(Scope.Thread)
+@OutputTimeUnit(TimeUnit.MICROSECONDS)
+@Fork(value = 3)
+@Warmup(iterations = 5, time = 1, timeUnit = TimeUnit.SECONDS)
+@Measurement(iterations = 5, time = 2, timeUnit = TimeUnit.SECONDS)
+public class UUIDBench {
+
+    @Param("20000")
+    private int size;
+
+    private UUID[] uuids;
+
+    private String[] uuidStrings;
+
+    private int index = 0;
+
+    @Setup
+    public void setup() {
+        uuids = new UUID[size];
+        uuidStrings = new String[size];
+        for (int i = 0; i < this.uuidStrings.length; i++) {
+            final UUID uuid = UUID.randomUUID();
+
+            this.uuids[i] = uuid;
+            this.uuidStrings[i] = uuid.toString();
+        }
+    }
+
+    @Setup(Level.Iteration)
+    public void setupIteration() {
+        index++;
+        if (index >= size) {
+            index = 0;
+        }
+    }
+
+    @Benchmark
+    public UUID fromString() {
+        return UUID.fromString(uuidStrings[index]);
+    }
+
+    @Benchmark
+    public String toString() {
+        return uuids[index].toString();
+    }
+}