[Sheepdog] [PATCH] sheep: retry read other copy in failure

[Liu Yuan]

On 04/18/2012 10:43 AM, Liu Yuan wrote:

> From: Liu Yuan <tailai.ly at taobao.com>
> 
> We have strong consistency for writing objects, so we can read
> any copy for data. In recovery stage, read cluser might fail and
> we should retry it.
> 
> - ask fix_object_consistency() to CREATE instead of WRITE in the case
> of object not found.
> 
> Signed-off-by: Liu Yuan <tailai.ly at taobao.com>
> ---
>  sheep/store.c |   48 ++++++++++++++++++++++++++++--------------------
>  1 files changed, 28 insertions(+), 20 deletions(-)
> 
> diff --git a/sheep/store.c b/sheep/store.c
> index ab21bd8..d4546cd 100644
> --- a/sheep/store.c
> +++ b/sheep/store.c
> @@ -306,7 +306,7 @@ static int do_local_io(struct request *req, uint32_t epoch);
>  
>  static int forward_read_obj_req(struct request *req)
>  {
> -	int i, n, nr, fd, ret;
> +	int i, n, nr, fd, ret = SD_RES_SUCCESS;
>  	unsigned wlen, rlen;
>  	struct sd_obj_req hdr = *(struct sd_obj_req *)&req->rq;
>  	struct sd_obj_rsp *rsp = (struct sd_obj_rsp *)&hdr;
> @@ -333,31 +333,39 @@ static int forward_read_obj_req(struct request *req)
>  
>  		if (is_myself(e[n].addr, e[n].port)) {
>  			ret = do_local_io(req, hdr.epoch);
> -			goto out;
> +			if (ret != SD_RES_SUCCESS)
> +				goto read_remote;
> +			return ret;
>  		}
>  	}
>  
> -	n = obj_to_sheep(e, nr, oid, 0);
> +read_remote:
> +	for (i = 0; i < copies; i++) {
> +		n = obj_to_sheep(e, nr, oid, i);
> +		if (is_myself(e[n].addr, e[n].port))
> +			continue;
>  
> -	fd = get_sheep_fd(e[n].addr, e[n].port, e[n].node_idx, hdr.epoch);
> -	if (fd < 0) {
> -		ret = SD_RES_NETWORK_ERROR;
> -		goto out;
> -	}
> +		fd = get_sheep_fd(e[n].addr, e[n].port, e[n].node_idx, hdr.epoch);
> +		if (fd < 0) {
> +			ret = SD_RES_NETWORK_ERROR;
> +			continue;
> +		}
>  
> -	wlen = 0;
> -	rlen = hdr.data_length;
> +		wlen = 0;
> +		rlen = hdr.data_length;
>  
> -	ret = exec_req(fd, (struct sd_req *)&hdr, req->data, &wlen, &rlen);
> +		ret = exec_req(fd, (struct sd_req *)&hdr, req->data, &wlen, &rlen);
>  
> -	if (ret) { /* network errors */
> -		del_sheep_fd(fd);
> -		ret = SD_RES_NETWORK_ERROR;
> -	} else {
> -		memcpy(&req->rp, rsp, sizeof(*rsp));
> -		ret = rsp->result;
> +		if (ret) { /* network errors */
> +			del_sheep_fd(fd);
> +			ret = SD_RES_NETWORK_ERROR;
> +			continue;
> +		} else {
> +			memcpy(&req->rp, rsp, sizeof(*rsp));
> +			ret = rsp->result;
> +			break;
> +		}
>  	}
> -out:
>  	return ret;
>  }
>  
> @@ -822,10 +830,10 @@ static int fix_object_consistency(struct request *req)
>  		goto out;
>  	}
>  
> -	hdr->opcode = SD_OP_WRITE_OBJ;
> +	hdr->opcode = SD_OP_CREATE_AND_WRITE_OBJ;
>  	hdr->flags = SD_FLAG_CMD_WRITE;
>  	hdr->oid = oid;
> -	req->op = get_sd_op(SD_OP_WRITE_OBJ);
> +	req->op = get_sd_op(hdr->opcode);
>  	ret = forward_write_obj_req(req);
>  	if (ret != SD_RES_SUCCESS) {
>  		eprintf("failed to write object %d\n", ret);


Applied.

Thanks,
Yuan