#pragma once

// The event-loop wakeup primitive (docs/adr/0020, docs/08-porting.md). EventLoop uses this
// to interrupt a blocked poll() from another thread or a signal handler — the eventfd
// mechanics themselves are Linux-only; every other OS backend just needs something
// poll()-able that signal()/drain() can drive the same way (docs/08 §"The seams": a
// self-pipe on macOS, an event object on Windows).
//
// One implementation file per OS under platform/<os>/wakeup.cpp; this header carries no
// OS types and no #ifdef (ADR 0020 decision 1).

namespace velox::daemon::rpc::platform {

class Wakeup {
public:
    Wakeup();
    ~Wakeup();

    Wakeup(const Wakeup&) = delete;
    Wakeup& operator=(const Wakeup&) = delete;

    // The fd to register with poll(2) for readability.
    int pollfd() const noexcept { return fd_; }

    // Make pollfd() readable. Async-signal-safe and thread-safe.
    void signal() noexcept;

    // Drain whatever signal() queued so pollfd() stops being readable. Call this from the
    // loop thread once pollfd() fires.
    void drain() noexcept;

private:
    int fd_ = -1;
};

}  // namespace velox::daemon::rpc::platform