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Nanaloveyuki
77 lines
2.1 KiB
Markdown
77 lines
2.1 KiB
Markdown
---
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name: queued-sink-dropped-count
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group: api
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category: sink
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update-time: 20260613
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description: Read the cumulative dropped-record count from a QueuedSink.
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key-word:
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- sink
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- queue
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- dropped
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- public
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---
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## Queued-sink-dropped-count
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Read the cumulative dropped-record count from a `QueuedSink[S]`. This helper exposes the direct sink-level loss metric when a bounded queue overflows.
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### Interface
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```moonbit
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pub fn[S] QueuedSink::dropped_count(self : QueuedSink[S]) -> Int {
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```
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#### input
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- `self : QueuedSink[S]` - Queued sink whose cumulative dropped-record metric should be inspected.
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#### output
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- `Int` - Number of dropped records reported by the queue wrapper.
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### Explanation
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Detailed rules explaining key parameters and behaviors
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- The counter value comes from `self.dropped_count.val`.
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- It increases when the queue is full and an incoming record cannot be kept without applying overflow handling.
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- The counter is cumulative for the lifetime of the concrete queued sink value.
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- This helper does not explain why drops happened beyond exposing the count.
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### How to Use
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Here are some specific examples provided.
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#### When Need Direct Queue Loss Visibility
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When a bounded queue may discard records under pressure:
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```moonbit
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if sink.dropped_count() > 0 {
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println("queue dropped records")
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}
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```
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In this example, direct queue loss becomes visible without inspecting internal fields manually.
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#### When Compare Overflow Tuning Changes
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When queue capacity or overflow policy should be checked operationally:
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```moonbit
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ignore(sink.dropped_count())
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```
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In this example, callers can compare the cumulative drop metric across different queue settings.
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### Error Case
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e.g.:
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- If the queue never overflows, this counter remains `0`.
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- If callers need a higher-level wrapper around runtime-configured sinks, `RuntimeSink::dropped_count()` or `ConfiguredLogger::dropped_count()` may fit better.
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### Notes
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1. This helper reports cumulative loss, not the exact overflow moment.
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2. Pair it with `pending_count()`, `drain()`, and queue configuration when investigating pressure.
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