Re: [dpdk-dev] [PATCH] lib/librte_hash: add rte_hash_del_key_fixed without compact

["Wang, Yipeng1" <yipeng1.wang@intel.com>]

> -----Original Message-----
> From: Lilijun (Jerry) <jerry.lilijun@huawei.com>
> Sent: Tuesday, May 12, 2020 6:28 PM
> To: Wang, Yipeng1 <yipeng1.wang@intel.com>; Honnappa Nagarahalli
> <Honnappa.Nagarahalli@arm.com>; 'dev@dpdk.org' <dev@dpdk.org>
> Cc: wangyunjian <wangyunjian@huawei.com>; xudingke
> <xudingke@huawei.com>; 'stable@dpdk.org' <stable@dpdk.org>; nd
> <nd@arm.com>; nd <nd@arm.com>
> Subject: 答复: [dpdk-dev] [PATCH] lib/librte_hash: add
> rte_hash_del_key_fixed without compact

<...>

> > [Yipeng]
> > Could you tell me more on the use case? Since insertion would also
> > invalidate the Iterator, do you insert keys only to new table during resizing?
> >
> [Lilijun (Jerry)]
> Yes, Insert only to new table. Because the resize process need take a write
> lock and the old table's key insertion are prevented by the lock now.
> Do you mean the key insertion may change other key's position by cuckoo
> hash algorithm and invalidate the iterator?
> That maybe a new question I haven't met yet.

[Wang, Yipeng] 
For cuckoo algorithm, if the table is relatively full, new inserted key could move other keys around in the table.
For example, when I insert A, A could move B to B's alternative bucket to make
space for A, that’s where the name "cuckoo" comes from. 😊
So if you insert keys into table, the iterators should be invalidated too. But as you said you only insert keys
to new table while you iterate only the old table right?