queue: add new BackpressureQueue[T] variant #9838
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Roasbeef
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queue/back_pressure_test.go
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| t, res.IsOk(), "Enqueue of 42 should not error: %v", res.Err(), | ||
| ) | ||
| require.True(t, | ||
| res.UnwrapOrFail(t), "Item 42 should have been dropped by "+ |
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nit. I was confused, because this can never fail, since you checked res.IsOk() above. But we are checking the success case of the result, which should be true. Maybe consider res.UnwrapOr(false)?
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I think can remove the above check, and just have it be UnwrapOrFail.
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With Enqueue returning an error now this makes so much more sense. 👍
In this commit, we add a new type of queue: the back pressure queue. This is a bounded queue based on a simple channel, that will consult a predicate to decide if we should preemptively drop a message or not. We then provide a sample predicate for this use case, based on random early dropping. Given a min and max threshold, we'll start to drop message randomly once we get past the min threshold, ramping up to the max threshold where we'll start to always drop the message.
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Pushed up a new version. PTAL. |
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Did a second pass. Mainly nits (line length! 😄) and some clarifications from my side about the use of generics in the tests.
Suffice to say that I really like this. I already used it in #10219 so I would love to see this merged.
@yyforyongyu Could you have a go at this as well?
queue/back_pressure_test.go
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| t, res.IsOk(), "Enqueue of 42 should not error: %v", res.Err(), | ||
| ) | ||
| require.True(t, | ||
| res.UnwrapOrFail(t), "Item 42 should have been dropped by "+ |
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With Enqueue returning an error now this makes so much more sense. 👍
| } | ||
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| // intQueueMachine is a concrete wrapper for queueMachine[int] for rapid. | ||
| type intQueueMachine struct { |
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No, I meant
type intQueueMachine struct {
tb rapid.TB
capacity int
queue *BackpressureQueue[int]
modelQueue []int
dropPredicate DropPredicate[int]
itemGenerator *rapid.Generator[int]
}
and take it from there.
| } | ||
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| // intQueueMachine is a concrete wrapper for queueMachine[int] for rapid. | ||
| type intQueueMachine struct { |
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This is what copilot came up with. Github doesn't allow me to upload .diff files, hence the .txt extension. no-generics.txt
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| // queueMachine is the generic state machine logic for testing | ||
| // BackpressureQueue. T must be comparable for use in assertions. | ||
| type queueMachine[T comparable] struct { |
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nit: line length
Will stop making these comments to not swamp the review with it, but there are several places where the max line length is exceeded.
| // | ||
| // This smooth ramp helps avoid tail-drop spikes, smooths queue occupancy, | ||
| // and gives early back-pressure signals to senders. | ||
| func RandomEarlyDrop[T any](minThreshold, maxThreshold int, opts ...REDOption) DropPredicate[T] { |
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@yyforyongyu: review reminder |
In this commit, we add a new type of queue: the back pressure queue. This is a bounded queue based on a simple channel, that will consult a predicate to decide if we should preemptively drop a message or not.
We then provide a sample predicate for this use case, based on random early dropping. Given a min and max threshold, we'll start to drop message randomly once we get past the min threshold, ramping up to the max threshold where we'll start to always drop the message.