Clarify empty string/NULL filter errors

[lttng-tools.git] / include / lttng / lttng.h

diff --git a/include/lttng/lttng.h b/include/lttng/lttng.h
index 0a12d9be75e4b97be6728bad11727105f4e68b8c..515e07c4e9703653c600e633d887ccae6f194957 100644 (file)
--- a/include/lttng/lttng.h
+++ b/include/lttng/lttng.h
@@ -509,16 +509,20 @@ extern int lttng_enable_event(struct lttng_handle *handle,
                struct lttng_event *ev, const char *channel_name);
 
 /*
- * Apply a filter expression to an event.
+ * Create or enable an event with a specific filter.
  *
- * If event_name is NULL, the filter is applied to all events of the channel.
- * If channel_name is NULL, a lookup of the event's channel is done.
- * If both are NULL, the filter is applied to all events of all channels.
- */
-extern int lttng_set_event_filter(struct lttng_handle *handle,
-               const char *event_name,
-               const char *channel_name,
+ * If the event you are trying to enable does not exist, it will be created,
+ * else it is enabled.
+ * If event_name is NULL, all events are enabled with that filter.
+ * If channel_name is NULL, the default channel is used (channel0) and created
+ * if not found.
+ * If filter_expression is NULL, an event without associated filter is
+ * created.
+ */
+extern int lttng_enable_event_with_filter(struct lttng_handle *handle,
+               struct lttng_event *event, const char *channel_name,
                const char *filter_expression);
+
 /*
  * Create or enable a channel.
  * The channel name cannot be NULL.
@@ -594,13 +598,15 @@ extern int lttng_health_check(enum lttng_health_component c);
 
 /*
  * For a given session name, this call checks if the data is ready to be read
- * or is still being extracted by the consumer(s) hence not ready to be used by
- * any readers.
+ * or is still being extracted by the consumer(s) (pending) hence not ready to
+ * be used by any readers.
  *
- * Return 0 if the data is _NOT_ available else 1 if the data is ready. On
- * error, a negative value is returned and readable by lttng_strerror().
+ * Return 0 if there is _no_ data pending in the buffers thus having a
+ * guarantee that the data can be read safely. Else, return 1 if there is still
+ * traced data is pending. On error, a negative value is returned and readable
+ * by lttng_strerror().
  */
-extern int lttng_data_available(const char *session_name);
+extern int lttng_data_pending(const char *session_name);
 
 #ifdef __cplusplus
 }