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6470700: Math.random() / Math.initRNG() uses "double checked locking"

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Replace class Random variable with a static final holder class

Reviewed-by: alanb, mduigou, chegar
This commit is contained in:
Brian Burkhalter 2013-08-22 13:32:22 -07:00 committed by Brian Burkhalter
parent 3cd2e9e099
commit ff7c51cd18
2 changed files with 6 additions and 16 deletions
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11
jdk/src/share/classes/java/lang/Math.java
View File

@ -698,11 +698,8 @@ public final class Math {
return 0; return 0;
} }
private static Random randomNumberGenerator; private static final class RandomNumberGeneratorHolder {
static final Random randomNumberGenerator = new Random();
private static synchronized Random initRNG() {
Random rnd = randomNumberGenerator;
return (rnd == null) ? (randomNumberGenerator = new Random()) : rnd;
} }
/** /**
@ -729,9 +726,7 @@ public final class Math {
* @see Random#nextDouble() * @see Random#nextDouble()
*/ */
public static double random() { public static double random() {
Random rnd = randomNumberGenerator; return RandomNumberGeneratorHolder.randomNumberGenerator.nextDouble();
if (rnd == null) rnd = initRNG();
return rnd.nextDouble();
} }
/** /**

11
jdk/src/share/classes/java/lang/StrictMath.java
View File

@ -678,11 +678,8 @@ public final class StrictMath {
return Math.round(a); return Math.round(a);
} }
private static Random randomNumberGenerator; private static final class RandomNumberGeneratorHolder {
static final Random randomNumberGenerator = new Random();
private static synchronized Random initRNG() {
Random rnd = randomNumberGenerator;
return (rnd == null) ? (randomNumberGenerator = new Random()) : rnd;
} }
/** /**
@ -709,9 +706,7 @@ public final class StrictMath {
* @see Random#nextDouble() * @see Random#nextDouble()
*/ */
public static double random() { public static double random() {
Random rnd = randomNumberGenerator; return RandomNumberGeneratorHolder.randomNumberGenerator.nextDouble();
if (rnd == null) rnd = initRNG();
return rnd.nextDouble();
} }
/** /**