Struct StderrTail 

pub struct StderrTail { /* private fields */ }

A background drain of one stderr stream. Keeps the most recent lines whose total size is at most max_bytes; older lines fall off the front.

Implementations

impl StderrTail

pub fn capture<R: Read + Send + 'static>( stderr: R, max_bytes: usize, map: impl Fn(&str) -> Option<String> + Send + 'static, on_line: impl Fn(&str) + Send + 'static, ) -> Self

Drain stderr on a thread. map sees every line first and returns the text to keep (redaction), or None to drop it. on_line receives the kept text as it arrives (forward to logs/telemetry).

pub fn plain<R: Read + Send + 'static>(stderr: R, max_bytes: usize) -> Self

Capture with no redaction and no forwarding.

pub fn snapshot(&self) -> String

The retained lines, oldest first, joined by newlines.

pub fn finish_within(&mut self, timeout: Duration) -> String

Like Self::finish but gives up after timeout (a grandchild that inherited stderr can keep the stream open after the child is gone) and returns what was captured so far.

pub fn finish(&mut self) -> String

Wait for the stream to end (the child exited) so the tail is complete.