Struct WakePipe 

pub struct WakePipe { /* private fields */ }

Wake notification built on pipe(2).

The pattern is:

• one thread blocks on the read end with poll(2)
• another thread writes one byte to the write end to signal “work exists”
• the waiter drains pending bytes before going back to sleep

Why use a pipe here:

• it gives us a real file descriptor that integrates with poll(2)
• it works on the Unix platforms smolvm targets
• it is simpler than building a custom condvar + timeout scheme around the smoltcp loop and Unix-stream writer

Implementations

impl WakePipe

pub fn new() -> Self

Create a non-blocking wake pipe.

Low-level steps:

pipe()               -> create read/write fds
fcntl(F_SETFL)       -> add O_NONBLOCK
fcntl(F_SETFD)       -> add FD_CLOEXEC
wrap in OwnedFd      -> move fd lifetime into Rust ownership

pub fn wake(&self)

Signal the waiting side.

Writing one byte is enough. The byte value itself does not matter; only readability of the pipe matters. Multiple writes coalesce naturally into “there is pending wake state”.

pub fn drain(&self)

Drain all pending wake bytes.

This resets the readiness state after a wake. Because the pipe is non-blocking, read <= 0 means “nothing more to drain right now”.

pub fn wait(&self, timeout: Option<Duration>) -> Result<bool>

Wait until the pipe is readable or the timeout elapses.

This is the low-level equivalent of “sleep until another thread signals me or the timeout expires”, but implemented in file-descriptor space so it composes with other polling logic.

pub fn as_raw_fd(&self) -> RawFd

File descriptor for poll(2).

Callers should treat this as a borrowed readiness handle, not as an fd they own or may close.

Trait Implementations

impl Clone for WakePipe

fn clone(&self) -> Self

Clone by duplicating both file descriptors.

Each clone refers to the same underlying pipe objects, so waking or draining from any clone affects the shared readiness state.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for WakePipe

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for WakePipe

fn default() -> Self

Returns the “default value” for a type.