NOTE:
Test environment is 750 MHz Athlon using JDK 1.3.0_02 with 256MB RAM
on Win2K.
Berin Loritsch wrote:
> My initial testing (consisting of running the TestCases several times)
> reveals the cost of an enqueue/dequeue operation. This consists of
> both single element vs. multiple element enqueue/dequeue operations.
> All calls are paired.
>
> The average cost of using the Default Queue is 1.156 usecs per
> enqueue/dequeue operation. This is pretty decent considering that the
> Queue is ThreadSafe (i.e. locking is performed). It uses an ArrayList
> to perform it's duties.
>
> The average cost of using the Fixed Size Queue is 884.0 nsecs per
> enqueue/dequeue operation. This is a little over half the cost of
> the DefaultQueue, and it is also ThreadSafe. It directly manipulates
> an array to perform it's duties.
>
> The array manipulation works like this:
>
> | 1 | 2 | 3 | 4 | 5 |
> * *
> S E
>
> S = Start
> E = End
>
> The current figure shows a queue with 1 element enqueued. When S=E,
> there are no elements enqueued. The next figure shows what happens
> when the element is dequeued:
>
> | 1 | 2 | 3 | 4 | 5 |
> **
> SE
>
> The Start pointer moves forward when there are elements to dequeue,
> and the End pointer moves forward when a new element is enqueued. It
> is also important to note that the entry where start is is nulled after
> it is retrieved.
>
> The algorithm wraps the pointers back to 0 when they reach the maximum.
>
> This moving pointer system works quite well, and never requires useless
> creation of objects or new queue sizes during the life of the Queue.
>
--
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deserve neither liberty nor safety."
- Benjamin Franklin
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