Interface VertxContextPRNG

All Known Implementing Classes:
PRNG
public interface VertxContextPRNG
A secure non blocking random number generator isolated to the current context. The PRNG is bound to the vert.x context and setup to close when the context shuts down.

When applicable, use of VertxContextPRNG rather than create new PRNG objects is helpful to keep the system entropy usage to the minimum avoiding potential blocking across the application.

The use of VertxContextPRNG is particularly appropriate when multiple handlers use random numbers.

Author:
Paulo Lopes

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    close()
    stop seeding the PRNG
    static VertxContextPRNG
    current()
    Get or create a secure non blocking random number generator using the current vert.x context.
    static VertxContextPRNG
    current(Context context)
    Get or create a secure non blocking random number generator using the provided vert.x context.
    static VertxContextPRNG
    current(Vertx vertx)
    Get or create a secure non blocking random number generator using the current vert.x instance.
    boolean
    nextBoolean()
    Returns a secure random boolean
    void
    nextBytes(byte[] bytes)
    Fills the given byte array with random bytes.
    double
    nextDouble()
    Returns a secure random double value.
    float
    nextFloat()
    Returns a secure random float value.
    double
    nextGaussian()
    Returns a secure random double value.
    int
    nextInt()
    Returns a secure random int
    int
    nextInt(int bound)
    Returns a secure random int, between 0 (inclusive) and the specified bound (exclusive).
    long
    nextLong()
    Returns a secure random long
    String
    nextString(int length)
    Returns a Base64 url encoded String of random data with the given length.

  • Method Details

    • current

      static VertxContextPRNG current()
      Get or create a secure non blocking random number generator using the current vert.x context. If there is no current context (i.e.: not running on the eventloop) then a IllegalStateException is thrown.

      Note, if a context isn't allowed to be used, for example, exceptions are thrown on getting and putting data, the VertxContextPRNG falls back to instantiate a new instance of the PRNG per call.

      Returns:
      A secure non blocking random number generator.
      Throws:
      IllegalStateException - when there is no Context instance available.

    • current

      static VertxContextPRNG current(Context context)
      Get or create a secure non blocking random number generator using the provided vert.x context. This method will not throw an exception.

      Note, if a context isn't allowed to be used, for example, exceptions are thrown on getting and putting data, the VertxContextPRNG falls back to instantiate a new instance of the PRNG per call.

      Parameters:
      context - a Vert.x context.
      Returns:
      A secure non blocking random number generator
      Throws:
      IllegalStateException - when there is no Vertx instance available.

    • current

      static VertxContextPRNG current(Vertx vertx)
      Get or create a secure non blocking random number generator using the current vert.x instance. Since the context might be different this method will attempt to use the current context first if available and then fall back to create a new instance of the PRNG.

      Note, if a context isn't allowed to be used, for example, exceptions are thrown on getting and putting data, the VertxContextPRNG falls back to instantiate a new instance of the PRNG per call.

      Parameters:
      vertx - a Vert.x instance.
      Returns:
      A secure non blocking random number generator.

    • close

      void close()
      stop seeding the PRNG

    • nextBytes

      void nextBytes(byte[] bytes)
      Fills the given byte array with random bytes.
      Parameters:
      bytes - a byte array.

    • nextString

      String nextString(int length)
      Returns a Base64 url encoded String of random data with the given length. The length parameter refers to the length of the String before the encoding step.
      Parameters:
      length - the desired string length before Base64 encoding.
      Returns:
      A base 64 encoded string.

    • nextInt

      int nextInt()
      Returns a secure random int
      Returns:
      random int.

    • nextInt

      int nextInt(int bound)
      Returns a secure random int, between 0 (inclusive) and the specified bound (exclusive).
      Parameters:
      bound - the upper bound (exclusive), which must be positive.
      Returns:
      random int.

    • nextBoolean

      boolean nextBoolean()
      Returns a secure random boolean
      Returns:
      random boolean.

    • nextLong

      long nextLong()
      Returns a secure random long
      Returns:
      random long.

    • nextFloat

      float nextFloat()
      Returns a secure random float value. The value is uniformly distributed between 0.0 and 1.0
      Returns:
      random float.

    • nextDouble

      double nextDouble()
      Returns a secure random double value. The value is uniformly distributed between 0.0 and 1.0
      Returns:
      random double.

    • nextGaussian

      double nextGaussian()
      Returns a secure random double value. The value is Gaussian ("normally") distributed with mean 0.0 and standard deviation 1.0
      Returns:
      random double.