[sheepdog] [PATCH V4 1/2] sheep: refactor gateway_forward_request

[Yunkai Zhang]

On Mon, Sep 3, 2012 at 6:20 PM, Liu Yuan <namei.unix at gmail.com> wrote:
> On 09/02/2012 08:59 PM, Yunkai Zhang wrote:
>> +static int forward_request_concurrently(struct sd_req *hdr,
>> +                                     void *data, unsigned int *wlen,
>> +                                     struct sd_vnode *target_vnodes[],
>> +                                     struct sd_rsp target_rsps[],
>> +                                     void *target_data[],
>> +                                     int nr_targets)
>
> This interface looks unnecessarily complex to me. I'd suggest changes like following
> untested patch , it is more generic and simpler, simply adding one more caller provided
> buffer to read response data if any.
>
> Thanks,
> Yuan
>
> =====================================================
> diff --git a/sheep/gateway.c b/sheep/gateway.c
> index 41d712b..690f0ac 100644
> --- a/sheep/gateway.c
> +++ b/sheep/gateway.c
> @@ -150,10 +150,12 @@ static inline void pfd_info_init(struct write_info *wi, struct pfd_info *pi)
>   *
>   * Return error code if any one request fails.
>   */
> -static int wait_forward_request(struct write_info *wi, struct sd_rsp *rsp)
> +static int wait_forward_request(struct write_info *wi, void *read_buffer)
>  {
>         int nr_sent, err_ret = SD_RES_SUCCESS, ret, pollret, i;
> -       struct pfd_info pi;;
> +       struct pfd_info pi;
> +       struct sd_rsp rsp;
> +       char *rb_pos = (char *)read_buffer;
>  again:
>         pfd_info_init(wi, &pi);
>         pollret = poll(pi.pfds, pi.nr, -1);
> @@ -174,23 +176,37 @@ again:
>                 if (re & (POLLERR | POLLHUP | POLLNVAL)) {
>                         err_ret = SD_RES_NETWORK_ERROR;
>                         finish_one_write_err(wi, i);
> -               } else if (re & POLLIN) {
> -                       if (do_read(pi.pfds[i].fd, rsp, sizeof(*rsp))) {
> +                       goto finish_write;
> +               }
> +               if (!(re & POLLIN)) {
> +                       eprintf("unhandled poll event\n");
> +                       goto finish_write;
> +               }
> +               if (do_read(pi.pfds[i].fd, &rsp, sizeof(rsp))) {
> +                       eprintf("remote node might have gone away\n");
> +                       err_ret = SD_RES_NETWORK_ERROR;
> +                       finish_one_write_err(wi, i);
> +                       goto finish_write;
> +               }
> +
> +               if (rsp.data_length && read_buffer) {
> +                       memcpy(rb_pos, wi->ent[i].nid, sizeof(wi->ent[i].nid));
> +                       rb_pos += sizeof(wi->ent[i].nid);
> +                       if (do_read(pi.pfds[i].fd, &read_buffer,
> +                                   rsp.data_length)) {
>                                 eprintf("remote node might have gone away\n");
>                                 err_ret = SD_RES_NETWORK_ERROR;
>                                 finish_one_write_err(wi, i);
>                                 goto finish_write;
>                         }
> -
> -                       ret = rsp->result;
> -                       if (ret != SD_RES_SUCCESS) {
> -                               eprintf("fail %"PRIx32"\n", ret);
> -                               err_ret = ret;
> -                       }
> -                       finish_one_write(wi, i);
> -               } else {
> -                       eprintf("unhandled poll event\n");
> +                       rb_pos += rsp.data_length;
>                 }
> +               ret = rsp.result;
> +               if (ret != SD_RES_SUCCESS) {
> +                       eprintf("fail %"PRIx32"\n", ret);
> +                       err_ret = ret;
> +               }
> +               finish_one_write(wi, i);
>         }
>  finish_write:
>         if (wi->nr_sent > 0)
> @@ -225,11 +241,10 @@ static inline void gateway_init_fwd_hdr(struct sd_req *fwd, struct sd_req *hdr)
>         fwd->proto_ver = SD_SHEEP_PROTO_VER;
>  }
>
> -static int gateway_forward_request(struct request *req)
> +static int gateway_forward_request(struct request *req, void *read_buffer)
>  {
> -       int i, err_ret = SD_RES_SUCCESS, ret, local = -1;
> +       int i, err_ret = SD_RES_SUCCESS, ret;
>         unsigned wlen;
> -       struct sd_rsp *rsp = (struct sd_rsp *)&req->rp;
>         struct sd_vnode *v;
>         struct sd_vnode *obj_vnodes[SD_MAX_COPIES];
>         uint64_t oid = req->rq.obj.oid;
> @@ -253,10 +268,6 @@ static int gateway_forward_request(struct request *req)
>                 struct sockfd *sfd;
>
>                 v = obj_vnodes[i];
> -               if (vnode_is_local(v)) {
> -                       local = i;
> -                       continue;
> -               }
>
>                 sfd = sheep_get_sockfd(&v->nid);
>                 if (!sfd) {
> @@ -274,21 +285,9 @@ static int gateway_forward_request(struct request *req)
>                 write_info_advance(&wi, v, sfd);
>         }
>
> -       if (local != -1 && err_ret == SD_RES_SUCCESS) {
> -               v = obj_vnodes[local];
> -
> -               assert(op);
> -               ret = sheep_do_op_work(op, req);
> -
> -               if (ret != SD_RES_SUCCESS) {
> -                       eprintf("fail to write local %"PRIx32"\n", ret);
> -                       err_ret = ret;
> -               }
> -       }
> -
>         dprintf("nr_sent %d, err %x\n", wi.nr_sent, err_ret);
>         if (wi.nr_sent > 0) {
> -               ret = wait_forward_request(&wi, rsp);
> +               ret = wait_forward_request(&wi, read_buffer);
>                 if (ret != SD_RES_SUCCESS)
>                         err_ret = ret;
>         }
> @@ -301,7 +300,7 @@ int gateway_write_obj(struct request *req)
>         if (sys->enable_write_cache && !req->local && !bypass_object_cache(req))
>                 return object_cache_handle_request(req);
>
> -       return gateway_forward_request(req);
> +       return gateway_forward_request(req, NULL);
>  }
>
>  int gateway_create_and_write_obj(struct request *req)
> @@ -309,10 +308,10 @@ int gateway_create_and_write_obj(struct request *req)
>         if (sys->enable_write_cache && !req->local && !bypass_object_cache(req))
>                 return object_cache_handle_request(req);
>
> -       return gateway_forward_request(req);
> +       return gateway_forward_request(req, NULL);
>  }
>
>  int gateway_remove_obj(struct request *req)
>  {
> -       return gateway_forward_request(req);
> +       return gateway_forward_request(req, NULL);
>  }


It's ok for me.


-- 
Yunkai Zhang
Work at Taobao