Trait LogSink

Source

pub trait LogSink: Send + Sync {
    // Required methods
    fn emit(&self, lvl: Level, msg: &str);
    fn emit_error(&self, msg: &str);
}

Expand description

Pluggable destination for diagnostic emissions. The default StderrSink preserves the linesmith [<level>]: <msg> format external scripts grep for; the TUI swaps in a CapturedSink for the duration of the alt-screen so macro emissions land in the warnings panel instead of corrupting the painted frame.

&self (not &mut self) so a sink instance can be shared via Arc<dyn LogSink>. The Send + Sync bound is what Arc<dyn _> requires and lets background plugin emitters share the slot safely with the render thread. The active-sink slot is an RwLock: emits take read locks (concurrent) and install_sink takes the write lock, which waits for in-flight emits to drain before swapping. This applies only to dispatches that go through emit / emit_error — a thread that holds its own Arc<dyn LogSink> (the prior returned by install_sink, or a future plugin handle) can still drive that sink directly after a swap.

Implementations must not call back into emit / emit_error or the lsm_warn! / lsm_debug! / lsm_error! macros from within their own emit / emit_error. The slot’s read lock is held across the dispatch, and std::sync::RwLock’s reentrancy is platform-defined — a recursive read can deadlock against a pending install_sink on writer-preferring runtimes (musl, Windows SRW). lsm-261p tracks evaluating a fair RwLock so this invariant can relax.

Required Methods§

Source

fn emit(&self, lvl: Level, msg: &str)

Emit a level-gated diagnostic. The caller has already confirmed the level is enabled — the sink writes unconditionally. Implementations defensively no-op on Level::Off rather than relying on the caller; the macros never pass Off, but emit() is pub.

Source

fn emit_error(&self, msg: &str)

Emit a structural-failure diagnostic. Always fires regardless of the configured level — LINESMITH_LOG=off users still see “the statusline broke” because there’s no other channel.