* Christian Babeux ([email protected]) wrote:
> When using the enable-event command in conjunction with the --filter option,
> a user can specify a filter expression to refine the trace output.
> 
> As stated in the lttng(1) man page, only the first activation of a filter on
> an event will work. Subsequent activation of any filter expression on the
> same event will fail.
> 
> e.g:
> 
> > lttng enable-event app:tp -s session -u --filter 'somefield > 42'
> 
> # Case: invalid filter expression
> > lttng enable-event app:tp -s session -u --filter 'invalid expression'
>   Error: Error setting filter
>   Warning: Some command(s) went wrong
> 
> > ...
> 
> # Case: filter already enabled for event app:tp
> > lttng enable-event app:tp -s session -u --filter 'someotherfield < 42'
>   Error: Error setting filter
>   Warning: Some command(s) went wrong
> 
> This commit differentiate the case where a filter was already set for the
> specified event from the generic 'Error setting filter' error message.
> 
> e.g:
> 
> > lttng enable-event app:tp -s session -u --filter 'somefield > 42'
> 
> # Case: invalid filter expression
> > lttng enable-event app:tp -s session -u --filter 'invalid expression'
>   Error: Error setting filter
>   Warning: Some command(s) went wrong
> 
> > ...
> 
> # Case: filter already enabled for event app:tp
> > lttng enable-event app:tp -s session -u --filter 'someotherfield < 42'
>   Error: Filter on event app:tp is already enabled (channel 0, session 
> session)
>   Warning: Some command(s) went wrong
> 
> Signed-off-by: Christian Babeux <[email protected]>

Acked-by: Mathieu Desnoyers <[email protected]>

Thanks!

Mathieu

> ---
>  src/bin/lttng/commands/enable_events.c | 22 ++++++++++++++++++++--
>  1 file changed, 20 insertions(+), 2 deletions(-)
> 
> diff --git a/src/bin/lttng/commands/enable_events.c 
> b/src/bin/lttng/commands/enable_events.c
> index a2c8a68..5a81fdb 100644
> --- a/src/bin/lttng/commands/enable_events.c
> +++ b/src/bin/lttng/commands/enable_events.c
> @@ -384,7 +384,16 @@ static int enable_events(char *session_name)
>                       ret = lttng_set_event_filter(handle, ev.name, 
> channel_name,
>                                               opt_filter);
>                       if (ret < 0) {
> -                             ERR("Error setting filter");
> +                             switch (-ret) {
> +                             case LTTCOMM_FILTER_EXIST:
> +                                     ERR("Filter on events is already 
> enabled (channel %s, session %s)",
> +                                             channel_name, session_name);
> +                                     break;
> +                             default:
> +                                     ERR("Error setting filter");
> +                                     break;
> +                             }
> +
>                               ret = -1;
>                               goto error;
>                       }
> @@ -554,7 +563,16 @@ static int enable_events(char *session_name)
>                       ret = lttng_set_event_filter(handle, ev.name,
>                               channel_name, opt_filter);
>                       if (ret < 0) {
> -                             ERR("Error setting filter");
> +                             switch (-ret) {
> +                             case LTTCOMM_FILTER_EXIST:
> +                                     ERR("Filter on event %s is already 
> enabled (channel %s, session %s)",
> +                                             event_name, channel_name, 
> session_name);
> +                                     break;
> +                             default:
> +                                     ERR("Error setting filter");
> +                                     break;
> +                             }
> +
>                               ret = -1;
>                               goto error;
>                       }
> -- 
> 1.7.11.4
> 

-- 
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com

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