File-sink-type

FileSink is the public native file sink type used for file-backed synchronous logging. It is the concrete sink type returned by file_sink(...), and it stores runtime file policy, availability state, formatter behavior, and failure counters.

Interface

pub struct FileSink {
  path : String
  append : Ref[Bool]
  default_append : Bool
  handle : Ref[FileHandle?]
  formatter : RecordFormatter
  auto_flush : Ref[Bool]
  default_auto_flush : Bool
  rotation : Ref[FileRotation?]
  default_rotation : FileRotation?
  open_failures : Ref[Int]
  write_failures : Ref[Int]
  flush_failures : Ref[Int]
  rotation_failures : Ref[Int]
}

output

• FileSink - Public native file sink type with runtime policy, state, and failure tracking.

Explanation

Detailed rules explaining key parameters and behaviors

• This is a public root struct, not a type alias.
• The current fields cover path, append mode, handle state, formatter, auto-flush policy, optional rotation policy, and failure counters.
• file_sink(...) constructs this type directly from path and policy inputs.
• The type exposes runtime helpers such as flush(), close(), reopen(), policy(), state(), and failure-counter accessors.

How to Use

Here are some specific examples provided.

When Need A Typed Native File Sink Value

When code should keep the concrete file sink type visible:

let sink : FileSink = file_sink("app.log")

In this example, the sink value stays explicit and keeps the file-backed runtime controls available.

When Need A Typed File-backed Logger

When logging should preserve the native file sink type in the logger:

let logger : Logger[FileSink] = Logger::new(file_sink("app.log"), target="file")

In this example, the concrete file sink remains part of the logger type.

Error Case

e.g.:

• FileSink itself does not have a runtime failure mode.

• Actual file availability, writes, flushes, and reopen behavior still depend on backend support and filesystem state.

Notes

1. Use file_sink(...) when you need a value of this type.

2. Use FileSinkState, FileSinkPolicy, and RuntimeFileState when you need exported snapshots or higher-level diagnostics rather than the live sink type itself.