[sheepdog] [PATCH v1] sheep/http: fix error in bucket_delete

[朱炳鹏]

Sorry, I'm confused and I can't agree with you. You said that bnode_lookup() will check every objects, but the code doesn't seem like it.  
Here is the code of bnode_lookup() that I taken from the master branch.
static int bnode_lookup(struct kv_bnode *bnode, uint32_t vid, const char *name)
{
	uint64_t hval, i;
	int ret;


	hval = sd_hash(name, strlen(name));
	for (i = 0; i < MAX_DATA_OBJS; i++) {
		uint32_t idx = (hval + i) % MAX_DATA_OBJS;
		uint64_t oid = vid_to_data_oid(vid, idx);


		ret = sd_read_object(oid, (char *)bnode, sizeof(*bnode), 0);
		if (ret != SD_RES_SUCCESS)
			goto out;
		if (strcmp(bnode->name, name) == 0)
			break;
	}


	if (i == MAX_DATA_OBJS)
		ret = SD_RES_NO_OBJ;
out:
	return ret;
}

Suppose container A and B has the same sd_hash() value, their bnodes will be stored in adjacent data objects. Then,
we delete container A and its bnode. When we call bnode_lookup() for container B,  sd_read_object() will return error.‍
I have read your another replied email. Do you mean we should just ignore the hash collision since it is really rare in practical‍ use?‍


------------------ Original ------------------
From:  "Liu Yuan";<namei.unix at gmail.com>;
Date:  Wed, Aug 6, 2014 04:17 PM
To:  "朱炳鹏"<nkuzbp at foxmail.com>; 
Cc:  "sheepdog"<sheepdog at lists.wpkg.org>; "Yu Fang"<bingpeng.zbp at alibaba-inc.com>; 
Subject:  Re: [sheepdog] [PATCH v1] sheep/http: fix error in bucket_delete



On Tue, Aug 05, 2014 at 08:33:46PM +0800, Bingpeng Zhu wrote:
> From: NankaiZBP <nkuzbp at foxmail.com>
> 
> In current implementation, When we create a bucket, we decide
> the bnode's location in account VDI using sd_hash(bucket_name)
> as key. We handle hash conflict by linear probing hash table.
> Here is the bug:
> When we delete a bucket, we can't discard its bnode. Because
> bnode_lookup() need it to find if some bucket exists or not
> by checking adjacent bnodes. Therefore, we just zero its
> bnode.name when client want to delete a bucket. When we create
> a bucket later, we can reuse the deleted bnode if they hash to
> the same location in account VDI.

No, bnode_lookup() will check every objects. What your said just applied to
onode_lookup(). There is no bug as your described for bnode_lookup().

Thanks
Yuan
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