On 11/4/11 10:50 AM, sebb wrote: > On 4 November 2011 17:44, Phil Steitz <phil.ste...@gmail.com> wrote: >> On 11/4/11 10:25 AM, sebb wrote: >>> On 4 November 2011 16:20, <pste...@apache.org> wrote: >>>> Author: psteitz >>>> Date: Fri Nov 4 16:20:05 2011 >>>> New Revision: 1197626 >>>> >>>> URL: http://svn.apache.org/viewvc?rev=1197626&view=rev >>>> Log: >>>> Changed default non-secure generator to Well19937c and changed default >>>> seeds to add system identity haschode to timestamp. JIRA: MATH-701. >>> You've actually use the object hashcode - did you mean to use >>> j.l.System.indentityHashcode() ? >> Yes, maybe I am wrong, but I thought that's what you got by default >> when hashcode is not overridden. What we want is just something >> that will be unique by instance (with high probability) and is >> relatively fast to compute. > Yes, you do get that if it is not overridden, but if the hashcode is > later overriden then: > - the Javadoc will not be accurate > - it may not be as quick to compute. > > It would be easy to overlook this in a future update, so I'd recommend > using what the Javadoc says.
Thanks for reviewing this. Fixed in r1197716. Phil > >> Phil >>>> Modified: >>>> >>>> commons/proper/math/trunk/src/main/java/org/apache/commons/math/random/RandomDataImpl.java >>>> >>>> Modified: >>>> commons/proper/math/trunk/src/main/java/org/apache/commons/math/random/RandomDataImpl.java >>>> URL: >>>> http://svn.apache.org/viewvc/commons/proper/math/trunk/src/main/java/org/apache/commons/math/random/RandomDataImpl.java?rev=1197626&r1=1197625&r2=1197626&view=diff >>>> ============================================================================== >>>> --- >>>> commons/proper/math/trunk/src/main/java/org/apache/commons/math/random/RandomDataImpl.java >>>> (original) >>>> +++ >>>> commons/proper/math/trunk/src/main/java/org/apache/commons/math/random/RandomDataImpl.java >>>> Fri Nov 4 16:20:05 2011 >>>> @@ -49,7 +49,7 @@ import org.apache.commons.math.util.Resi >>>> * instance to generate non-secure data and a {@link >>>> java.security.SecureRandom} >>>> * instance to provide data for the <code>nextSecureXxx</code> methods. If >>>> no >>>> * <code>RandomGenerator</code> is provided in the constructor, the >>>> default is >>>> - * to use a generator based on {@link java.util.Random}. To plug in a >>>> different >>>> + * to use a {@link Well19937c} generator. To plug in a different >>>> * implementation, either implement <code>RandomGenerator</code> directly >>>> or >>>> * extend {@link AbstractRandomGenerator}. >>>> * <p> >>>> @@ -81,10 +81,10 @@ import org.apache.commons.math.util.Resi >>>> * When a new <code>RandomDataImpl</code> is created, the underlying random >>>> * number generators are <strong>not</strong> initialized. If you do not >>>> * explicitly seed the default non-secure generator, it is seeded with the >>>> - * current time in milliseconds on first use. The same holds for the >>>> secure >>>> - * generator. If you provide a <code>RandomGenerator</code> to the >>>> constructor, >>>> - * however, this generator is not reseeded by the constructor nor is it >>>> reseeded >>>> - * on first use.</li> >>>> + * current time in milliseconds plus the system identity hash code on >>>> first use. >>>> + * The same holds for the secure generator. If you provide a >>>> <code>RandomGenerator</code> >>>> + * to the constructor, however, this generator is not reseeded by the >>>> constructor >>>> + * nor is it reseeded on first use.</li> >>>> * <li> >>>> * The <code>reSeed</code> and <code>reSeedSecure</code> methods delegate >>>> to the >>>> * corresponding methods on the underlying <code>RandomGenerator</code> and >>>> @@ -827,7 +827,8 @@ public class RandomDataImpl implements R >>>> /** >>>> * Returns the RandomGenerator used to generate non-secure random data. >>>> * <p> >>>> - * Creates and initializes a default generator if null. >>>> + * Creates and initializes a default generator if null. Uses a {@link >>>> Well19937c} >>>> + * generator with {@code System.currentTimeMillis() + hashCode()} as >>>> the default seed. >>>> * </p> >>>> * >>>> * @return the Random used to generate random data >>>> @@ -835,8 +836,7 @@ public class RandomDataImpl implements R >>>> */ >>>> private RandomGenerator getRan() { >>>> if (rand == null) { >>>> - rand = new JDKRandomGenerator(); >>>> - rand.setSeed(System.currentTimeMillis()); >>>> + rand = new Well19937c(System.currentTimeMillis() + >>>> hashCode()); >>>> } >>>> return rand; >>>> } >>>> @@ -844,7 +844,8 @@ public class RandomDataImpl implements R >>>> /** >>>> * Returns the SecureRandom used to generate secure random data. >>>> * <p> >>>> - * Creates and initializes if null. >>>> + * Creates and initializes if null. Uses >>>> + * {@code System.currentTimeMillis() + hashCode()} as the default >>>> seed. >>>> * </p> >>>> * >>>> * @return the SecureRandom used to generate secure random data >>>> @@ -852,7 +853,7 @@ public class RandomDataImpl implements R >>>> private SecureRandom getSecRan() { >>>> if (secRand == null) { >>>> secRand = new SecureRandom(); >>>> - secRand.setSeed(System.currentTimeMillis()); >>>> + secRand.setSeed(System.currentTimeMillis() + hashCode()); >>>> } >>>> return secRand; >>>> } >>>> >>>> >>>> >>> --------------------------------------------------------------------- >>> To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org >>> For additional commands, e-mail: dev-h...@commons.apache.org >>> >>> >> >> --------------------------------------------------------------------- >> To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org >> For additional commands, e-mail: dev-h...@commons.apache.org >> >> > --------------------------------------------------------------------- > To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org > For additional commands, e-mail: dev-h...@commons.apache.org > > --------------------------------------------------------------------- To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org For additional commands, e-mail: dev-h...@commons.apache.org
