Struct DrainState 

pub struct DrainState<F>
where
    F: FnMut(&[u8]) -> bool,
{ /* private fields */ }

Orchestrates non-blocking process I/O.

DrainState tracks the state of stdin, stdout, and stderr pipes for a single process. It handles the multiplexing of data between these pipes and internal buffers.

Example

while !drain.is_done() {
    let mut events = Vec::new();
    reactor.wait(&mut events, 64, -1)?;
    for ev in events {
        // Map event tokens to drain calls...
    }
}

Implementations

impl<F> DrainState<F>

where F: FnMut(&[u8]) -> bool,

pub fn new( stdin_fd: Option<Fd>, stdin_buf: Option<Box<[u8]>>, stdout_fd: Option<Fd>, stderr_fd: Option<Fd>, limit: usize, early_exit: Option<F>, ) -> Result<Self, CoreError>

Initialize a new drain state for the provided descriptors.

This consumes the descriptors and sets them to non-blocking mode.

Errors

• EBADF: One of the provided file descriptors is invalid.

pub fn is_done(&self) -> bool

Returns true if all pipes have been closed or fully drained.

pub fn write_stdin(&mut self) -> Result<bool, CoreError>

Perform a non-blocking write to stdin if pending.

Returns Ok(true) if the write buffer is empty or the descriptor is closed.

Errors

• EPIPE: The child process closed its reading end of the pipe.
• EIO: Low-level I/O error.

pub fn read_fd(&mut self, is_stdout: bool) -> Result<bool, CoreError>

Perform a non-blocking read from stdout or stderr.

Returns Ok(true) if the stream reached EOF or the early-exit condition was met.

Errors

• EOVERFLOW: The captured output exceeded the specified limit.
• EIO: Low-level I/O error.

pub fn into_parts(self) -> (Vec<u8>, Vec<u8>)

Consume the state and return (stdout, stderr) buffers.

pub fn output_limit_exceeded(&self) -> bool

Return whether the combined stdout+stderr output limit was exceeded.

pub fn stdout_early_exited(&self) -> bool

Return whether stdout was explicitly stopped by the early-exit predicate.