Package io.github.pr0methean.betterrandom.seed

Enum DefaultSeedGenerator

  • All Implemented Interfaces:
    SeedGenerator, Serializable, Comparable<DefaultSeedGenerator>
    public enum DefaultSeedGenerator
extends Enum<DefaultSeedGenerator>
implements SeedGenerator

    Seed generator that is the default for the program where it is running. PRNGs that are serialized using one program's default and deserialized in another program will use the latter's default seed generator, which is part of the static state. This means a PRNG's serial form won't specify a particular seed generator if it was constructed without specifying one.

    The default implementation maintains multiple strategies for seed generation and will delegate to the best one available at any moment. It uses, in order of preference:

    1. DevRandomSeedGenerator with 128-byte buffer
    2. AnuQuantumSeedClient with 1024-byte buffer
    3. RandomDotOrgAnonymousClient with 625-byte buffer
    4. SecureRandomSeedGenerator with no buffer

    The reasons to use DefaultSeedGenerator rather than its delegate directly are twofold:

    • RandomSeeder instances that are serialized and deserialized will respect any change of delegate that has been made in the destination program with set(SeedGenerator).
    • You avoid having to pass a SeedGenerator as an explicit constructor parameter to descendants of BaseRandom.
    Author:
    Daniel Dyer, Chris Hennick

    • Enum Constant Detail

      • DEFAULT_SEED_GENERATOR

        public static final DefaultSeedGenerator DEFAULT_SEED_GENERATOR
        Singleton instance.

    • Field Detail

      • DEFAULT_RETRY_DELAY

        public static final Duration DEFAULT_RETRY_DELAY

    • Method Detail

      • values

        public static DefaultSeedGenerator[] values()
        Returns an array containing the constants of this enum type, in the order they are declared. This method may be used to iterate over the constants as follows: 
        for (DefaultSeedGenerator c : DefaultSeedGenerator.values())
    System.out.println(c);
        Returns:
        an array containing the constants of this enum type, in the order they are declared

      • valueOf

        public static DefaultSeedGenerator valueOf​(String name)
        Returns the enum constant of this type with the specified name. The string must match exactly an identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)
        Parameters:
        name - the name of the enum constant to be returned.
        Returns:
        the enum constant with the specified name
        Throws:
        IllegalArgumentException - if this enum type has no constant with the specified name
        NullPointerException - if the argument is null

      • get

        public static SeedGenerator get()
        Returns the current delegate used by this class's singleton instance.
        Returns:
        the current delegate

      • set

        public static void set​(SeedGenerator delegate)
        Sets the default seed generator (a delegate used by this class's singleton instance).
        Parameters:
        delegate - the new delegate

      • generateSeed

        public void generateSeed​(byte[] output)
                  throws SeedException
        Generates a seed value for a random number generator in an existing array.

        Generates a seed by trying each of the available strategies in turn until one succeeds. Tries the most suitable strategy first and eventually degrades to the least suitable (but guaranteed to work) strategy.

        Specified by:
        generateSeed in interface SeedGenerator
        Parameters:
        output - The array that is to be populated with the seed.
        Throws:
        SeedException - If a seed cannot be generated for any reason.

      • generateSeed

        public byte[] generateSeed​(int length)
                    throws SeedException
        Description copied from interface: SeedGenerator
        Generates and returns a seed value for a random number generator as a new array.
        Specified by:
        generateSeed in interface SeedGenerator
        Parameters:
        length - The length of the seed to generate (in bytes).
        Returns:
        A byte array containing the seed data.
        Throws:
        SeedException - If a seed cannot be generated for any reason.