src/share/classes/java/util/UUID.java
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rev 9925 : 8006627: UUID to/from String performance should be improved by reducing object allocations
Reviewed-by: TBD
Contributed-by: Steven Schlansker <stevenschlansker@gmail.com>, Claes Redestad <claes.redestad@oracle.com>
@@ -25,10 +25,13 @@
package java.util;
import java.security.*;
+import sun.misc.JavaLangAccess;
+import sun.misc.SharedSecrets;
+
/**
* A class that represents an immutable universally unique identifier (UUID).
* A UUID represents a 128-bit value.
*
* <p> There exist different variants of these global identifiers. The methods
@@ -86,10 +89,12 @@
*
* @serial
*/
private final long leastSigBits;
+ private static final JavaLangAccess jla = SharedSecrets.getJavaLangAccess();
+
/*
* The random number generator used by this class to create random
* based UUIDs. In a holder class to defer initialization until needed.
*/
private static class Holder {
@@ -187,25 +192,28 @@
* If name does not conform to the string representation as
* described in {@link #toString}
*
*/
public static UUID fromString(String name) {
- String[] components = name.split("-");
- if (components.length != 5)
- throw new IllegalArgumentException("Invalid UUID string: "+name);
- for (int i=0; i<5; i++)
- components[i] = "0x"+components[i];
+ int dash1 = name.indexOf('-', 0);
+ int dash2 = name.indexOf('-', dash1 + 1);
+ int dash3 = name.indexOf('-', dash2 + 1);
+ int dash4 = name.indexOf('-', dash3 + 1);
+
+ if (name.indexOf('-', dash4 + 1) > 0) {
+ throw new IllegalArgumentException("Invalid UUID string: " + name);
+ }
- long mostSigBits = Long.decode(components[0]).longValue();
+ long mostSigBits = jla.parseUnsignedLong(name, 16, 0, dash1) & 0xffffffffL;
mostSigBits <<= 16;
- mostSigBits |= Long.decode(components[1]).longValue();
+ mostSigBits |= jla.parseUnsignedLong(name, 16, dash1 + 1, dash2) & 0xffffL;
mostSigBits <<= 16;
- mostSigBits |= Long.decode(components[2]).longValue();
+ mostSigBits |= jla.parseUnsignedLong(name, 16, dash2 + 1, dash3) & 0xffffL;
- long leastSigBits = Long.decode(components[3]).longValue();
+ long leastSigBits = jla.parseUnsignedLong(name, 16, dash3 + 1, dash4) & 0xffffL;
leastSigBits <<= 48;
- leastSigBits |= Long.decode(components[4]).longValue();
+ leastSigBits |= jla.parseUnsignedLong(name, 16, dash4 + 1, name.length()) & 0xffffffffffffL;
return new UUID(mostSigBits, leastSigBits);
}
// Field Accessor Methods
@@ -371,21 +379,26 @@
* }</pre></blockquote>
*
* @return A string representation of this {@code UUID}
*/
public String toString() {
- return (digits(mostSigBits >> 32, 8) + "-" +
- digits(mostSigBits >> 16, 4) + "-" +
- digits(mostSigBits, 4) + "-" +
- digits(leastSigBits >> 48, 4) + "-" +
- digits(leastSigBits, 12));
- }
-
- /** Returns val represented by the specified number of hex digits. */
- private static String digits(long val, int digits) {
- long hi = 1L << (digits * 4);
- return Long.toHexString(hi | (val & (hi - 1))).substring(1);
+ char[] chars = new char[36];
+ digits(mostSigBits >> 32, chars, 0, 8);
+ chars[8] = '-';
+ digits(mostSigBits >> 16, chars, 9, 4);
+ chars[13] = '-';
+ digits(mostSigBits, chars, 14, 4);
+ chars[18] = '-';
+ digits(leastSigBits >> 48, chars, 19, 4);
+ chars[23] = '-';
+ digits(leastSigBits, chars, 24, 12);
+ return jla.newStringUnsafe(chars);
+ }
+
+ private static void digits(long val, char[] chars, int offset, int len) {
+ long hi = 1L << (len * 4);
+ jla.formatUnsignedLong(hi | (val & (hi - 1)), 4, chars, offset, len);
}
/**
* Returns a hash code for this {@code UUID}.
*