📝 Fix policy test and doc

2026-07-27 18:32:20 +00:00 · 2026-07-07 10:28:16 +08:00
parent d3bff1305d
commit 3bac025acf
20 changed files with 844 additions and 60 deletions
@@ -0,0 +1,79 @@
+---
+name: runtime-sink-file-state-or-none
+group: api
+category: runtime
+update-time: 20260707
+description: Read the current file sink snapshot from a RuntimeSink only when it is actually file-backed.
+key-word:
+    - runtime
+    - sink
+    - file
+    - truthful
+---
+
+## Runtime-sink-file-state-or-none
+
+Read the current file sink snapshot from a `RuntimeSink` only when it is actually file-backed.
+
+This is the truthful companion to `file_state()`. Prefer it when diagnostics or recovery logic must not confuse fallback snapshots with real file state.
+
+### Interface
+
+```moonbit
+pub fn RuntimeSink::file_state_or_none(self : RuntimeSink) -> FileSinkState? {
+```
+
+#### input
+
+- `self : RuntimeSink` - Runtime sink whose file state snapshot should be inspected.
+
+#### output
+
+- `FileSinkState?` - `Some(snapshot)` when the runtime sink is file-backed, otherwise `None`.
+
+### Explanation
+
+Detailed rules explaining key parameters and behaviors
+
+- Plain `File` runtime variants return `Some(live_snapshot)`.
+- `QueuedFile` runtime variants forward the wrapped inner file sink snapshot as `Some(live_snapshot)`.
+- Non-file runtime variants return `None`.
+- This helper is broader than individual counters or policy reads because it returns the aggregated file snapshot without fallback synthesis.
+
+### How to Use
+
+Here are some specific examples provided.
+
+#### When Need Truthful File Health Diagnostics
+
+When support output should include file state only for real file-backed sinks:
+```moonbit
+match sink.file_state_or_none() {
+  Some(state) => println(stringify_file_sink_state(state, pretty=true))
+  None => ()
+}
+```
+
+In this example, no compatibility snapshot is fabricated for non-file sinks.
+
+#### When Need State Without Queue Expansion
+
+When code only needs the file snapshot and not queue metadata:
+```moonbit
+let maybe_state = sink.file_state_or_none()
+```
+
+In this example, `None` cleanly signals missing file semantics.
+
+### Error Case
+
+e.g.:
+- If the runtime sink is not file-backed, the method returns `None`.
+
+- If callers also need queue metrics for queued file sinks, prefer `file_runtime_state()`.
+
+### Notes
+
+1. Prefer this helper over `file_state()` for truthful runtime diagnostics.
+
+2. `file_state()` remains available as the compatibility fallback API.