[sheepdog] [PATCH v3 3/8] sheep: make gateway to retry when received SD_RES_OLD_NODE_VER

[Liu Yuan]

On 05/24/2012 11:37 AM, levin li wrote:

> From: levin li <xingke.lwp at taobao.com>
> 
> When gateway requests get SD_RES_OLD_NODE_VER in io_op_done(),
> it means epoch of gateway is older than peer, and peer has set
> response's epoch with its system epoch, then gateway should check
> whether its system epoch has reach peer's system epoch which in
> req->rp.epoch, and whether the result is SD_RES_OLD_NODE_VER,
> if so, the request should be pushed into wait_epoch_queue to
> wait until system epoch change, but if system epoch has reached
> peer's system epoch, retry this request at once.
> 
> Signed-off-by: levin li <xingke.lwp at taobao.com>
> ---
>  sheep/sdnet.c |   29 +++++++++++++++++++++++------
>  1 file changed, 23 insertions(+), 6 deletions(-)
> 
> diff --git a/sheep/sdnet.c b/sheep/sdnet.c
> index cd3311e..efdd1bf 100644
> --- a/sheep/sdnet.c
> +++ b/sheep/sdnet.c
> @@ -105,8 +105,14 @@ static void io_op_done(struct work *work)
>  	case SD_RES_NETWORK_ERROR:
>  	case SD_RES_WAIT_FOR_JOIN:
>  	case SD_RES_WAIT_FOR_FORMAT:
> -		if (!(req->rq.flags & SD_FLAG_CMD_IO_LOCAL))
> -			goto retry;
> +		if (!(req->rq.flags & SD_FLAG_CMD_IO_LOCAL)) {
> +			if (req->rp.epoch > sys->epoch &&
> +				req->rp.result == SD_RES_OLD_NODE_VER) {
> +				list_add_tail(&req->request_list,
> +						&sys->wait_rw_queue);
> +			} else
> +				goto retry;
> +		}
>  		break;
>  	case SD_RES_EIO:
>  		if (is_access_local(req, hdr->obj.oid)) {
> @@ -264,11 +270,22 @@ void resume_wait_epoch_requests(void)
>  
>  	list_for_each_entry_safe(req, t, &sys->wait_rw_queue,
>  				 request_list) {
> -
> -		list_del(&req->request_list);
> -		list_add_tail(&req->request_list, &sys->request_queue);
> -		process_request_event_queues();
> +		switch (req->rp.result) {
> +		case SD_RES_OLD_NODE_VER:
> +			/* retry as gateway. */
> +			req->rq.epoch = sys->epoch;
> +			put_vnode_info(req->vnodes);
> +			req->vnodes = get_vnode_info();
> +			setup_access_to_local_objects(req);
> +		case SD_RES_NEW_NODE_VER:
> +			list_del(&req->request_list);
> +			list_add_tail(&req->request_list, &sys->request_queue);
> +			break;
> +		default:
> +			break;
> +		}
>  	}


Both sender and receiver use the same wait_rw_queue, we'd better comment
out which code is for which one.

> +	process_request_event_queues();
>  }
>  
>  static void queue_request(struct request *req)