📝 document runtime sink append path methods

2026-07-27 18:32:20 +00:00 · 2026-06-13 22:59:12 +08:00
parent bf7512d113
commit 65605f6b59
4 changed files with 228 additions and 0 deletions
@@ -0,0 +1,76 @@
+---
+name: runtime-sink-file-set-append-mode
+group: api
+category: runtime
+update-time: 20260613
+description: Update the append-mode policy used by a file-backed RuntimeSink for later reopen behavior.
+key-word:
+    - runtime
+    - sink
+    - file
+    - public
+---
+
+## Runtime-sink-file-set-append-mode
+
+Update the append-mode policy used by a file-backed `RuntimeSink`. This helper changes future reopen behavior without forcing an immediate reopen on the runtime sink.
+
+### Interface
+
+```moonbit
+pub fn RuntimeSink::file_set_append_mode(self : RuntimeSink, append : Bool) -> Bool {
+```
+
+#### input
+
+- `self : RuntimeSink` - Runtime sink whose append-mode policy should change.
+- `append : Bool` - New append-mode policy.
+
+#### output
+
+- `Bool` - Whether the policy update was applied.
+
+### Explanation
+
+Detailed rules explaining key parameters and behaviors
+
+- Plain `File` runtime variants update their stored append policy and return `true`.
+- `QueuedFile` runtime variants forward the policy update to the wrapped inner `FileSink` and return `true`.
+- This helper updates policy only; it does not force immediate reopen.
+- Non-file runtime variants return `false`.
+
+### How to Use
+
+Here are some specific examples provided.
+
+#### When Need To Change Future Reopen Behavior On A Runtime Sink
+
+When runtime recovery should later prefer append mode explicitly:
+```moonbit
+ignore(sink.file_set_append_mode(true))
+```
+
+In this example, later reopen operations will use the updated append policy.
+
+#### When Want To Separate Policy Mutation From Reopen Timing
+
+When code should update policy now and reopen later:
+```moonbit
+ignore(sink.file_set_append_mode(false))
+ignore(sink.file_reopen_with_current_policy())
+```
+
+In this example, policy mutation and reopen timing remain separate decisions on the runtime sink.
+
+### Error Case
+
+e.g.:
+- If the runtime sink is not file-backed, the method returns `false`.
+
+- If callers need an immediate reopen as part of the same operation, one of the reopen helpers should be used afterward.
+
+### Notes
+
+1. This helper changes stored policy, not live file-handle state by itself.
+
+2. It is useful when recovery logic wants to stage reopen behavior in advance.