[lttng-dev] [LTTNG-TOOLS PATCH v2 1/2] Command to detach a live viewer session

[Jérémie Galarneau]

Would you mind rebasing both patches on master? These will not apply
on the relayd refactor introduced in 2.7.

Jérémie

On Thu, Jul 30, 2015 at 11:52 AM, Julien Desfossez
<jdesfossez at efficios.com> wrote:
> The LTTNG_VIEWER_DETACH_SESSION command allows the viewer to detach from
> the session it is currently attached to without requiring it to close
> the network connection. This allows the relayd to release its reference
> on the session and eventually clear it if it is destroyed on the
> consumer.
>
> Fixes: #853
>
> Signed-off-by: Julien Desfossez <jdesfossez at efficios.com>
> ---
>  src/bin/lttng-relayd/live.c             | 73 +++++++++++++++++++++++++++++++++
>  src/bin/lttng-relayd/lttng-viewer-abi.h | 18 ++++++++
>  2 files changed, 91 insertions(+)
>
> diff --git a/src/bin/lttng-relayd/live.c b/src/bin/lttng-relayd/live.c
> index 562a7fa..221ec43 100644
> --- a/src/bin/lttng-relayd/live.c
> +++ b/src/bin/lttng-relayd/live.c
> @@ -1733,6 +1733,76 @@ end:
>         return ret;
>  }
>
> +/*
> + * Detach a viewer session.
> + *
> + * Return 0 on success or else a negative value.
> + */
> +static
> +int viewer_detach_session(struct relay_connection *conn)
> +{
> +       int ret, found;
> +       struct lttng_viewer_detach_session_response resp;
> +       struct lttng_viewer_detach_session_request request;
> +       struct relay_session *session, *tmp_session;
> +       uint64_t to_close;
> +
> +       DBG("Viewer detach session received");
> +
> +       assert(conn);
> +
> +       health_code_update();
> +
> +       /* Receive the request from the connected client. */
> +       ret = recv_request(conn->sock, &request, sizeof(request));
> +       if (ret < 0) {
> +               goto end;
> +       }
> +       to_close = be64toh(request.session_id);
> +
> +       if (!conn->viewer_session) {
> +               resp.status = htobe32(LTTNG_VIEWER_DETACH_SESSION_ERR);
> +               goto send_reply;
> +       }
> +
> +       health_code_update();
> +
> +       memset(&resp, 0, sizeof(resp));
> +       DBG("Cleaning connection of session ID %" PRIu64, to_close);
> +
> +       found = 0;
> +       rcu_read_lock();
> +       cds_list_for_each_entry_safe(session, tmp_session,
> +                       &conn->viewer_session->sessions_head,
> +                       viewer_session_list) {
> +               if (session->id == to_close) {
> +                       DBG("Cleaning connection of session ID %" PRIu64, session->id);
> +                       cleanup_session(conn, session);
> +                       found = 1;
> +                       break;
> +               }
> +       }
> +       rcu_read_unlock();
> +
> +       if (!found) {
> +               resp.status = htobe32(LTTNG_VIEWER_DETACH_SESSION_ERR);
> +       } else {
> +               resp.status = htobe32(LTTNG_VIEWER_DETACH_SESSION_OK);
> +       }
> +
> +send_reply:
> +       health_code_update();
> +       ret = send_response(conn->sock, &resp, sizeof(resp));
> +       if (ret < 0) {
> +               goto end;
> +       }
> +       health_code_update();
> +       ret = 0;
> +
> +end:
> +       return ret;
> +}
> +
>
>  /*
>   * live_relay_unknown_command: send -1 if received unknown command
> @@ -1797,6 +1867,9 @@ int process_control(struct lttng_viewer_cmd *recv_hdr,
>         case LTTNG_VIEWER_CREATE_SESSION:
>                 ret = viewer_create_session(conn);
>                 break;
> +       case LTTNG_VIEWER_DETACH_SESSION:
> +               ret = viewer_detach_session(conn);
> +               break;
>         default:
>                 ERR("Received unknown viewer command (%u)", be32toh(recv_hdr->cmd));
>                 live_relay_unknown_command(conn);
> diff --git a/src/bin/lttng-relayd/lttng-viewer-abi.h b/src/bin/lttng-relayd/lttng-viewer-abi.h
> index f9bce98..9b4bc1a 100644
> --- a/src/bin/lttng-relayd/lttng-viewer-abi.h
> +++ b/src/bin/lttng-relayd/lttng-viewer-abi.h
> @@ -48,6 +48,7 @@ enum lttng_viewer_command {
>         LTTNG_VIEWER_GET_METADATA       = 6,
>         LTTNG_VIEWER_GET_NEW_STREAMS    = 7,
>         LTTNG_VIEWER_CREATE_SESSION     = 8,
> +       LTTNG_VIEWER_DETACH_SESSION     = 9,
>  };
>
>  enum lttng_viewer_attach_return_code {
> @@ -105,6 +106,11 @@ enum lttng_viewer_create_session_return_code {
>         LTTNG_VIEWER_CREATE_SESSION_ERR         = 2,
>  };
>
> +enum lttng_viewer_detach_session_return_code {
> +       LTTNG_VIEWER_DETACH_SESSION_OK          = 1,
> +       LTTNG_VIEWER_DETACH_SESSION_ERR         = 2,
> +};
> +
>  struct lttng_viewer_session {
>         uint64_t id;
>         uint32_t live_timer;
> @@ -232,4 +238,16 @@ struct lttng_viewer_create_session_response {
>         uint32_t status;
>  } __attribute__((__packed__));
>
> +/*
> + * LTTNG_VIEWER_DETACH_SESSION payload.
> + */
> +struct lttng_viewer_detach_session_request {
> +       uint64_t session_id;
> +} __attribute__((__packed__));
> +
> +struct lttng_viewer_detach_session_response {
> +       /* enum lttng_viewer_detach_session_return_code */
> +       uint32_t status;
> +} __attribute__((__packed__));
> +
>  #endif /* LTTNG_VIEWER_ABI_H */
> --
> 1.9.1
>



-- 
Jérémie Galarneau
EfficiOS Inc.
http://www.efficios.com