token bucket

class TokenBucket(msgPerSecond:Long, bucketSize:Long) {

    var prev = 0L
    var tokens = bucketSize

    def limit(func: => Any): Any = {
        val current = System.currentTimeMillis
        val delta = current-prev
        prev = current
        tokens += delta/1000.0 * msgPerSecond
        if (tokens > bucketSize) 
            tokens = bucketSize
        if (tokens > 0) 
            func
            
        tokens -= 1
    }
}

scala>  var tb = new TokenBucket(10, 6)
tb: TokenBucket = TokenBucket@5c2f4f8b

scala> (1 to 10) foreach( i => tb.limit { println(i) })
1
2
3
4
5
6