sleepWasi

fn sleepWasi(t: *Threaded, timeout: Io.Timeout) Io.Cancelable!void {
    const t_io = io(t);
    const w = std.os.wasi;

    const clock: w.subscription_clock_t = if (timeout.toDurationFromNow(t_io)) |d| .{
        .id = clockToWasi(d.clock),
        .timeout = std.math.lossyCast(u64, d.raw.nanoseconds),
        .precision = 0,
        .flags = 0,
    } else .{
        .id = .MONOTONIC,
        .timeout = std.math.maxInt(u64),
        .precision = 0,
        .flags = 0,
    };
    const in: w.subscription_t = .{
        .userdata = 0,
        .u = .{
            .tag = .CLOCK,
            .u = .{ .clock = clock },
        },
    };
    var event: w.event_t = undefined;
    var nevents: usize = undefined;
    const syscall: Syscall = try .start();
    _ = w.poll_oneoff(&in, &event, 1, &nevents);
    syscall.finish();
}