Async Executor

descriptors. Currently sshd inlines syscall3(SYS_POLL, ...) directly — a. Why it matters: The reactor needs poll() to block on multiple file. Focus on `PollFd` and `poll` in `userspace/syscall-lib/src/lib.rs` while you trace the snippet.

View on GitHub

userspace daemon, not just sshd. The dual std/no_std feature flag pattern. Why it matters: A dedicated crate keeps the executor reusable by any. Focus on `async_rt` and `std` in `userspace/async-rt/Cargo.toml` while you trace the snippet.

[features]
default = ["std"]
std = ["libc"]
alloc = []

[dependencies]
syscall-lib = { path = "../syscall-lib" }
libc = { version = "0.2", optional = true }

[dev-dependencies]
libc = "0.2"

View on GitHub

waker.wake() when it has data ready, and the executor must know which task. Why it matters: The Waker is the core async primitive — sunset calls. Focus on `Task` and `task_waker` in `userspace/async-rt/src/task.rs` while you trace the snippet.

/// A single-threaded async task wrapping a future and its waker state.
///
/// This is a compatibility shim that wraps the new `TaskHeader`.
/// It will be removed when the executor is rewritten in Phase 2.
pub struct Task {
    #[allow(dead_code)]
    pub(crate) future: Pin<Box<dyn Future<Output = ()>>>,
    pub(crate) header: Arc<TaskHeader>,
}

View on GitHub