Struct LineSink 

pub struct LineSink { /* private fields */ }

A rotating file sink for bytes the caller has already framed as complete lines — captured child output, forwarded worker rings, anything that is already a log line and must not be re-formatted.

The tracing layer is process-global by construction: one init per process, one destination. A supervisor needs one rotating file PER CHILD, and those bytes must reach the child’s own file unchanged rather than becoming events in the supervisor’s log. Without this type the only options are duplicating the rotation code (which then drifts from the crate that owns the policy) or shipping unrotated files (which is how a log reaches 936 MB unnoticed).

The caller owns framing: write_line appends a single trailing newline if the bytes do not already end with one, and writes exactly once so two pipes feeding one sink cannot interleave a partial line. Rotation and pruning are the same policy the layer uses, because it is the same code.

Implementations

impl LineSink

pub fn open(path: &Path, retention: Retention) -> Result<Self>

Opens (or creates) path with retention, pruning aged generations the way the layer’s own sink does on open.

pub fn open_at( path: &Path, retention: Retention, now: SystemTime, ) -> Result<Self>

open with an explicit clock, so a caller can test rotation and age pruning without sleeping.

pub fn write_line(&mut self, line: &[u8]) -> Result<()>

Writes one complete line, rotating first if it would exceed the cap.

pub fn write_line_at(&mut self, line: &[u8], now: SystemTime) -> Result<()>

write_line with an explicit clock.