Package org.drasyl.util

Class TokenBucket

java.lang.Object

org.drasyl.util.TokenBucket

public class TokenBucket
extends Object

This class implements the token bucket algorithm as a leaky bucket. This means that the bucket has a finite capacity and added tokens that exceed this capacity are lost. The bucket is filled with new tokens at a constant time rate.

This algorithm allows rate-limiting operations (e.g. number of messages sent per time unit). The bucket capacity can be used to control whether capacities unused in the past may be used up later, or whether they "overflow" from the bucket and are lost unused.

This implementation has been inspired by: token-bucket

Constructor Summary

Constructors

Constructor	Description
TokenBucket(long capacity, Duration refillInterval, boolean doBusyWait)	Creates a new leaky token bucket.

Method Summary

Modifier and Type	Method	Description
long	availableTokens()	Returns the number of available tokens in the bucket.
void	consume()	Consumes a token from the bucket.

Methods inherited from class java.lang.Object

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

Constructor Details

TokenBucket

public TokenBucket(long capacity,
 Duration refillInterval,
 boolean doBusyWait)

Creates a new leaky token bucket.

Parameters:

capacity - overall capacity of the token bucket

refillInterval - refill token at a fixed interval

doBusyWait - specifies if busy waiting should be used when calling consume() or not. busy waiting allows a more efficient consumption of tokens, but blocks a thread permanently. should only be used with refill intervals of less than 20 milliseconds.

Throws:

IllegalArgumentException - if capacity or refillInterval contain non-positive values

Method Details

consume

public void consume()

Consumes a token from the bucket. If the bucket does not currently contain a token, this method blocks until a token becomes available.

availableTokens

public long availableTokens()

Returns the number of available tokens in the bucket.

Returns:

numebr of available tokens in the bucket