Package io.github.pr0methean.betterrandom.seed

Class SimpleRandomSeeder

java.lang.Object

io.github.pr0methean.betterrandom.util.Looper

io.github.pr0methean.betterrandom.seed.SimpleRandomSeeder

All Implemented Interfaces:

Serializable

Direct Known Subclasses:

LegacyRandomSeeder

public class SimpleRandomSeeder
extends Looper

Thread that loops over ByteArrayReseedableRandom instances and reseeds them. No EntropyCountingRandom will be reseeded when it's already had more input than output.

Author:

Chris Hennick

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	SimpleRandomSeeder.DefaultThreadFactory	A ThreadFactory that sets the name and priority of the threads it creates.

Field Summary

Fields

Modifier and Type	Field	Description
protected Set<ByteArrayReseedableRandom>	byteArrayPrngs	Holds ByteArrayReseedableRandom instances that should be reseeded when their entropy is low, or as often as possible if they don't implement EntropyCountingRandom.
protected Set<ByteArrayReseedableRandom>	byteArrayPrngsThisIteration	Holds instances that are being reseeded during the current iteration, so that PRNGs can be added and removed in the middle of an iteration without the ConcurrentModificationException that would otherwise arise.
protected static long	DEFAULT_STOP_IF_EMPTY_FOR_NANOS	Default waiting time before an empty instance terminates if still empty.
protected static long	POLL_INTERVAL	Time in seconds to wait before checking again whether any PRNGs need more entropy.
protected SeedGenerator	seedGenerator	The seed generator this seeder uses.
protected long	stopIfEmptyForNanos	Time in nanoseconds after which this thread will terminate if no PRNGs are attached.
protected Condition	waitForEntropyDrain	Signaled by an associated BaseRandom when it runs out of entropy.
protected Condition	waitWhileEmpty	Signaled when a PRNG is added.

Fields inherited from class io.github.pr0methean.betterrandom.util.Looper

DEFAULT_THREAD_FACTORY, factory, lock, thread, threadLock

Constructor Summary

Constructors

Constructor	Description
SimpleRandomSeeder(SeedGenerator seedGenerator)	Creates an instance using a SimpleRandomSeeder.DefaultThreadFactory.
SimpleRandomSeeder(SeedGenerator seedGenerator, ThreadFactory threadFactory)	Creates an instance whose thread will terminate if no PRNGs have been associated with it for 5 seconds.
SimpleRandomSeeder(SeedGenerator seedGenerator, ThreadFactory threadFactory, long stopIfEmptyForNanos)	Creates an instance.

Method Summary

Modifier and Type	Method	Description
void	add(ByteArrayReseedableRandom... randoms)	Adds ByteArrayReseedableRandom instances.
void	add(Collection<? extends ByteArrayReseedableRandom> randoms)	Adds ByteArrayReseedableRandom instances.
protected void	clear()	Removes all PRNGs from this seeder.
protected <T> Set<T>	createSynchronizedWeakHashSet()	Creates and returns a thread-safe Set backed by a WeakHashMap.
boolean	equals(Object o)
SeedGenerator	getSeedGenerator()	Returns the SeedGenerator this seeder uses.
int	hashCode()
protected void	initTransientFields()	Initializes the transient instance fields for this class.
boolean	isEmpty()	Returns true if no Random instances are registered with this LegacyRandomSeeder.
protected boolean	iterate()	The task that will be iterated until it returns false.
void	remove(Collection<? extends Random> randoms)	Removes PRNGs so that they will no longer be reseeded.
void	remove(Random... randoms)	Removes PRNGs so that they will no longer be reseeded.
protected boolean	reseedByteArrayReseedableRandoms()	Reseeds all the PRNGs that need reseeding in byteArrayPrngsThisIteration, then clears that set.
protected void	reseedWithLong(Random random)	Generates an 8-byte seed, converts it to a long and calls Random.setSeed(long).
void	shutDown()	Shut down this thread even if Random instances are registered with it.
void	stopIfEmpty()	Shut down this thread if no Random instances are registered with it.
protected void	unregisterWithAll(Set<?> randoms)	Informs the given PRNGs that they no longer have a seed generator.
void	wakeUp()	Ensures this seeder's thread is started, and signals conditions it may be waiting on.

Methods inherited from class io.github.pr0methean.betterrandom.util.Looper

interrupt, isRunning, start

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Field Detail

POLL_INTERVAL

protected static final long POLL_INTERVAL

Time in seconds to wait before checking again whether any PRNGs need more entropy.

See Also:

Constant Field Values

DEFAULT_STOP_IF_EMPTY_FOR_NANOS

protected static final long DEFAULT_STOP_IF_EMPTY_FOR_NANOS

Default waiting time before an empty instance terminates if still empty.

See Also:

Constant Field Values

seedGenerator

protected final SeedGenerator seedGenerator

The seed generator this seeder uses.

byteArrayPrngs

protected transient Set<ByteArrayReseedableRandom> byteArrayPrngs

Holds ByteArrayReseedableRandom instances that should be reseeded when their entropy is low, or as often as possible if they don't implement EntropyCountingRandom.

byteArrayPrngsThisIteration

protected transient Set<ByteArrayReseedableRandom> byteArrayPrngsThisIteration

Holds instances that are being reseeded during the current iteration, so that PRNGs can be added and removed in the middle of an iteration without the ConcurrentModificationException that would otherwise arise.

waitWhileEmpty

protected transient Condition waitWhileEmpty

Signaled when a PRNG is added.

waitForEntropyDrain

protected transient Condition waitForEntropyDrain

Signaled by an associated BaseRandom when it runs out of entropy.

stopIfEmptyForNanos

protected final long stopIfEmptyForNanos

Time in nanoseconds after which this thread will terminate if no PRNGs are attached.

Constructor Detail

SimpleRandomSeeder

public SimpleRandomSeeder(SeedGenerator seedGenerator,
                          ThreadFactory threadFactory)

Creates an instance whose thread will terminate if no PRNGs have been associated with it for 5 seconds.

Parameters:

seedGenerator - the seed generator

threadFactory - the ThreadFactory that will create this seeder's thread

SimpleRandomSeeder

public SimpleRandomSeeder(SeedGenerator seedGenerator)

Creates an instance using a SimpleRandomSeeder.DefaultThreadFactory.

Parameters:

seedGenerator - the seed generator

SimpleRandomSeeder

public SimpleRandomSeeder(SeedGenerator seedGenerator,
                          ThreadFactory threadFactory,
                          long stopIfEmptyForNanos)

Creates an instance.

Parameters:

seedGenerator - the seed generator

threadFactory - the ThreadFactory that will create this seeder's thread

stopIfEmptyForNanos - time in nanoseconds after which this thread will terminate if no PRNGs are attached

Method Detail

remove

public void remove(Random... randoms)

Removes PRNGs so that they will no longer be reseeded.

Parameters:

randoms - the PRNGs to remove

remove

public void remove(Collection<? extends Random> randoms)

Removes PRNGs so that they will no longer be reseeded.

Parameters:

randoms - the PRNGs to remove

add

public void add(ByteArrayReseedableRandom... randoms)

Adds ByteArrayReseedableRandom instances.

Parameters:

randoms - the PRNGs to start reseeding

add

public void add(Collection<? extends ByteArrayReseedableRandom> randoms)

Adds ByteArrayReseedableRandom instances.

Parameters:

randoms - the PRNGs to start reseeding

wakeUp

public void wakeUp()

Ensures this seeder's thread is started, and signals conditions it may be waiting on.

equals

public boolean equals(Object o)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object

initTransientFields

protected void initTransientFields()

Initializes the transient instance fields for this class. Called by constructors and during deserialization.

createSynchronizedWeakHashSet

protected <T> Set<T> createSynchronizedWeakHashSet()

Creates and returns a thread-safe Set backed by a WeakHashMap.

Type Parameters:

T - the set element type

Returns:

an empty mutable thread-safe Set that holds only weak references to its members

iterate

protected boolean iterate()

Description copied from class: Looper

The task that will be iterated until it returns false. Cannot be abstract for serialization reasons, but must be overridden in subclasses if they are instantiated without a target Runnable.

Specified by:

iterate in class Looper

Returns:

true if this thread should iterate again.

reseedByteArrayReseedableRandoms

protected boolean reseedByteArrayReseedableRandoms()

Reseeds all the PRNGs that need reseeding in byteArrayPrngsThisIteration, then clears that set.

Returns:

true if at least one PRNG was reseeded; false otherwise

reseedWithLong

protected void reseedWithLong(Random random)

Generates an 8-byte seed, converts it to a long and calls Random.setSeed(long).

Parameters:

random - the PRNG to reseed

shutDown

public void shutDown()

Shut down this thread even if Random instances are registered with it.

clear

protected void clear()

Removes all PRNGs from this seeder.

unregisterWithAll

protected void unregisterWithAll(Set<?> randoms)

Informs the given PRNGs that they no longer have a seed generator. Only affects those that support BaseRandom.setRandomSeeder(SimpleRandomSeeder).

Parameters:

randoms - the PRNGs to unregister with

isEmpty

public boolean isEmpty()

Returns true if no Random instances are registered with this LegacyRandomSeeder.

Returns:

true if no Random instances are registered with this LegacyRandomSeeder.

stopIfEmpty

public void stopIfEmpty()

Shut down this thread if no Random instances are registered with it.

getSeedGenerator

public SeedGenerator getSeedGenerator()

Returns the SeedGenerator this seeder uses.

Returns:

this seeder's SeedGenerator