init

pub fn init(k: *Kqueue, gpa: Allocator, options: InitOptions) !void {
    assert(options.n_threads != 0);

    const n_threads = @max(1, options.n_threads orelse std.Thread.getCpuCount() catch 1);
    const threads_size = n_threads * @sizeOf(Thread);
    const idle_stack_end_offset = std.mem.alignForward(usize, threads_size + idle_stack_size, std.heap.page_size_max);
    const allocated_slice = try gpa.alignedAlloc(u8, .of(Thread), idle_stack_end_offset);
    errdefer gpa.free(allocated_slice);
    k.* = .{
        .gpa = gpa,
        .mutex = .init,
        .main_fiber_buffer = undefined,
        .threads = .{
            .allocated = @ptrCast(allocated_slice[0..threads_size]),
            .reserved = 1,
            .active = 1,
        },
    };
    const main_fiber: *Fiber = @ptrCast(&k.main_fiber_buffer);
    main_fiber.* = .{
        .required_align = {},
        .context = undefined,
        .awaiter = null,
        .queue_next = null,
        .cancel_thread = null,
        .awaiting_completions = .empty,
    };
    const main_thread = &k.threads.allocated[0];
    Thread.self = main_thread;
    const idle_stack_end: [*]align(16) usize = @ptrCast(@alignCast(allocated_slice[idle_stack_end_offset..].ptr));
    (idle_stack_end - 1)[0..1].* = .{@intFromPtr(k)};
    main_thread.* = .{
        .thread = undefined,
        .idle_context = switch (builtin.cpu.arch) {
            .aarch64 => .{
                .sp = @intFromPtr(idle_stack_end),
                .fp = 0,
                .pc = @intFromPtr(&mainIdleEntry),
            },
            .x86_64 => .{
                .rsp = @intFromPtr(idle_stack_end - 1),
                .rbp = 0,
                .rip = @intFromPtr(&mainIdleEntry),
            },
            else => @compileError("unimplemented architecture"),
        },
        .current_context = &main_fiber.context,
        .ready_queue = null,
        .kq_fd = try createFileDescriptor(),
        .idle_search_index = 1,
        .steal_ready_search_index = 1,
        .wait_queues = .empty,
    };
    errdefer closeFd(main_thread.kq_fd);
    std.log.debug("created main idle {*}", .{&main_thread.idle_context});
    std.log.debug("created main {*}", .{main_fiber});
}