sleep

fn sleep(userdata: ?*anyopaque, timeout: Io.Timeout) Io.Cancelable!void {
    const ev: *Evented = @ptrCast(@alignCast(userdata));

    const timespec: linux.kernel_timespec, const clock: Io.Clock, const timeout_flags: u32 = timespec: switch (timeout) {
        .none => .{
            .{
                .sec = std.math.maxInt(i64),
                .nsec = std.time.ns_per_s - 1,
            },
            .awake,
            linux.IORING_TIMEOUT_ABS,
        },
        .duration => |duration| {
            const ns = duration.raw.toNanoseconds();
            break :timespec .{
                .{
                    .sec = @intCast(@divFloor(ns, std.time.ns_per_s)),
                    .nsec = @intCast(@mod(ns, std.time.ns_per_s)),
                },
                duration.clock,
                0,
            };
        },
        .deadline => |deadline| {
            const ns = deadline.raw.toNanoseconds();
            break :timespec .{
                .{
                    .sec = @intCast(@divFloor(ns, std.time.ns_per_s)),
                    .nsec = @intCast(@mod(ns, std.time.ns_per_s)),
                },
                deadline.clock,
                linux.IORING_TIMEOUT_ABS,
            };
        },
    };
    var cancel_region: CancelRegion = .init();
    defer cancel_region.deinit();
    const thread = try cancel_region.awaitIoUring();
    thread.enqueue().* = .{
        .opcode = .TIMEOUT,
        .flags = 0,
        .ioprio = 0,
        .fd = 0,
        .off = 0,
        .addr = @intFromPtr(&timespec),
        .len = 1,
        .rw_flags = timeout_flags | @as(u32, switch (clock) {
            .real => linux.IORING_TIMEOUT_REALTIME,
            else => 0,
            .boot => linux.IORING_TIMEOUT_BOOTTIME,
        }),
        .user_data = @intFromPtr(cancel_region.fiber),
        .buf_index = 0,
        .personality = 0,
        .splice_fd_in = 0,
        .addr3 = 0,
        .resv = 0,
    };
    ev.yield(null, .nothing);
    // Handles SUCCESS as well as clock not available and unexpected
    // errors. The user had a chance to check clock resolution before
    // getting here, which would have reported 0, making this a legal
    // amount of time to sleep.
}