Unable to accomplish throttling

[suchigg]

Hello,
I tried to follow documentation to implement an API call throttling as described here but without any success.
I found in an old thread that "Token-bucket math model is not addressed to satisfy hard limits like N permit /M time. Please read this discussion #128 " but this looks in contrary to the documentation description.
Thanks in advance

[vladimir-bukhtoyarov]

Hello @suchigg

Please provide the code(and comments) that show the problem.

[suchigg]

Hello Vladimir and thank you for your support
This is the code I wrote to make some tests.

`public class BucketTest {

public static void main(String[] args) throws InterruptedException {
	Bandwidth operationalLimit = Bandwidth.simple(30, Duration.ofSeconds(30));
	Bucket bucket = Bucket.builder()
						.addLimit(operationalLimit)
						.build();

	while (true) {
		System.out.printf("available tokens: %d \n", bucket.getAvailableTokens());
		bucket.asScheduler().consume(1, Executors.newScheduledThreadPool(1));
		doSomething();
	}
}

private static void doSomething() throws InterruptedException {
	Thread.sleep(250);
	System.out.println("doSomething Method Called at: " + LocalDateTime.now());
}

}`

this is the output:

available tokens: 30
doSomething Method Called at: 2022-09-01T09:20:42.938936300
available tokens: 29
doSomething Method Called at: 2022-09-01T09:20:43.221216200
available tokens: 28
doSomething Method Called at: 2022-09-01T09:20:43.476211100
available tokens: 27
doSomething Method Called at: 2022-09-01T09:20:43.728993200
available tokens: 27
doSomething Method Called at: 2022-09-01T09:20:43.981990900
available tokens: 26
doSomething Method Called at: 2022-09-01T09:20:44.234343500
available tokens: 25
doSomething Method Called at: 2022-09-01T09:20:44.484530100
available tokens: 24
doSomething Method Called at: 2022-09-01T09:20:44.735714200
available tokens: 24
doSomething Method Called at: 2022-09-01T09:20:45.000307200
available tokens: 23
doSomething Method Called at: 2022-09-01T09:20:45.252219600
available tokens: 22
doSomething Method Called at: 2022-09-01T09:20:45.503864400
available tokens: 21
doSomething Method Called at: 2022-09-01T09:20:45.767503400
available tokens: 21
doSomething Method Called at: 2022-09-01T09:20:46.032356800
available tokens: 20
doSomething Method Called at: 2022-09-01T09:20:46.295146300
available tokens: 19
doSomething Method Called at: 2022-09-01T09:20:46.545747500
available tokens: 18
doSomething Method Called at: 2022-09-01T09:20:46.798313900
available tokens: 18
doSomething Method Called at: 2022-09-01T09:20:47.063313200
available tokens: 17
doSomething Method Called at: 2022-09-01T09:20:47.327592500
available tokens: 16
doSomething Method Called at: 2022-09-01T09:20:47.591051500
available tokens: 15
doSomething Method Called at: 2022-09-01T09:20:47.856183900
available tokens: 15
doSomething Method Called at: 2022-09-01T09:20:48.120618
available tokens: 14
doSomething Method Called at: 2022-09-01T09:20:48.373246100
available tokens: 13
doSomething Method Called at: 2022-09-01T09:20:48.638287800
available tokens: 12
doSomething Method Called at: 2022-09-01T09:20:48.890334400
available tokens: 12
doSomething Method Called at: 2022-09-01T09:20:49.141428200
available tokens: 11
doSomething Method Called at: 2022-09-01T09:20:49.391572400
available tokens: 10
doSomething Method Called at: 2022-09-01T09:20:49.646186700
available tokens: 9
doSomething Method Called at: 2022-09-01T09:20:49.911499800
available tokens: 9
doSomething Method Called at: 2022-09-01T09:20:50.163498900
available tokens: 8
doSomething Method Called at: 2022-09-01T09:20:50.428686900
available tokens: 7
doSomething Method Called at: 2022-09-01T09:20:50.681012300
available tokens: 7
doSomething Method Called at: 2022-09-01T09:20:50.932664700
available tokens: 6
doSomething Method Called at: 2022-09-01T09:20:51.197654500
available tokens: 5
doSomething Method Called at: 2022-09-01T09:20:51.461185500
available tokens: 4
doSomething Method Called at: 2022-09-01T09:20:51.711748800
available tokens: 4
doSomething Method Called at: 2022-09-01T09:20:51.976455300
available tokens: 3
doSomething Method Called at: 2022-09-01T09:20:52.242367200
available tokens: 2
doSomething Method Called at: 2022-09-01T09:20:52.506275
available tokens: 1
doSomething Method Called at: 2022-09-01T09:20:52.771202500
available tokens: 1
doSomething Method Called at: 2022-09-01T09:20:53.039756400
available tokens: 0
doSomething Method Called at: 2022-09-01T09:20:53.303001300
available tokens: -1
doSomething Method Called at: 2022-09-01T09:20:53.567111100
available tokens: -2
doSomething Method Called at: 2022-09-01T09:20:53.832249600
available tokens: -2
doSomething Method Called at: 2022-09-01T09:20:54.083250300
available tokens: -3
doSomething Method Called at: 2022-09-01T09:20:54.349360700
available tokens: -4
doSomething Method Called at: 2022-09-01T09:20:54.601604
available tokens: -5
doSomething Method Called at: 2022-09-01T09:20:54.866427300
available tokens: -5
doSomething Method Called at: 2022-09-01T09:20:55.118027400
available tokens: -6
doSomething Method Called at: 2022-09-01T09:20:55.369084800
available tokens: -7
doSomething Method Called at: 2022-09-01T09:20:55.634133900
available tokens: -8
doSomething Method Called at: 2022-09-01T09:20:55.897683200
available tokens: -8
doSomething Method Called at: 2022-09-01T09:20:56.163242300
available tokens: -9
doSomething Method Called at: 2022-09-01T09:20:56.429173400
available tokens: -10
doSomething Method Called at: 2022-09-01T09:20:56.694414100
available tokens: -10

The expected behavior, based on the documentation i linked, is that it's not possible to have negative numbers of tokens.
I tried to change Bandwith as Bandwidth.classic(30, Refill.intervally(30, Duration.ofSeconds(30))); and make some other attempt using ConsumptionProbe to obtain nanos to reset and do some math, but without success.

Thank you in advance

[vladimir-bukhtoyarov]

It is bug in documentation. I will fix it. You need to use asBlocking instead of asScheduler in case of you need to block current thread until requested amount of tokens become available.

[suchigg]

Thank you for the reply.
Another question. is there a way to start token regeneration only after the first tryConsume call and reset if after a threshold time?
If i understand how the library works, refill time of bandwidth is independent of token consumption, so i think i need to create some type of mechanism to start the bucket when is used for the first time and reset it after a certain time has passed

[vladimir-bukhtoyarov]

is there a way to start token regeneration only after the first tryConsume

No, there is no such functionality.

and reset if after a threshold time

The same. There is no such functionality

[suchigg]

Thank you again for the answer, i suppose i need to implement something custom then, unfortunately.
Anyway, your library looks amazing, good job!

Kind regards,
Luca