init

    fn init(free_index: Index, parent: Parent, name: []const u8, estimated_total_items: usize) Node {
        assert(parent == .none or @backingInt(parent) < node_storage_buffer_len);

        const storage = storageByIndex(free_index);
        @atomicStore(u32, &storage.completed_count, 0, .monotonic);
        // Avoid u32 max int which is used to indicate a special state.
        const saturated_total_count = @min(std.math.maxInt(u32) - 1, estimated_total_items);
        @atomicStore(u32, &storage.estimated_total_count, saturated_total_count, .monotonic);
        const name_len = @min(max_name_len, name.len);
        copyAtomicStore(storage.name[0..name_len], name[0..name_len]);
        if (name_len < storage.name.len)
            @atomicStore(u8, &storage.name[name_len], 0, .monotonic);

        const parent_ptr = parentByIndex(free_index);
        if (std.debug.runtime_safety) {
            assert(@atomicLoad(Node.Parent, parent_ptr, .monotonic) == .unused);
        }
        @atomicStore(Node.Parent, parent_ptr, parent, .monotonic);

        return .{ .index = free_index.toOptional() };
    }