Lttng-ctl: Expose sessiond cmd_clear_session command

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

diff --git a/include/lttng/session.h b/include/lttng/session.h
index 4e515ad7703bc03b3bb5530118063f29ac7051f5..dff6b45d40dedcf09001d76c1c7124f10c5e49d9 100644 (file)
--- a/include/lttng/session.h
+++ b/include/lttng/session.h
@@ -84,18 +84,66 @@ extern int lttng_create_session_snapshot(const char *name,
 extern int lttng_create_session_live(const char *name, const char *url,
                unsigned int timer_interval);
 
+/*
+ * Clear a tracing session.
+ *
+ * Clear the data buffers and trace data.
+ *
+ * For sessions saving trace data to disk and streaming over the network to a
+ * relay daemon, the buffers content and existing stream files are cleared when
+ * the clear command is issued.
+ *
+ * For snapshot sessions (flight recorder), only the buffer content is cleared.
+ * Prior snapshots are individually recorded to disk, and are therefore
+ * untouched by this "clear" command.
+ *
+ * For live sessions streaming over network to a relay daemon, the buffers
+ * will be cleared, and the files on the relay daemon side will be cleared as
+ * well. However, any active live trace viewer currently reading an existing
+ * trace packet will be able to proceed to read that packet entirely before
+ * skipping over cleared stream data.
+ *
+ * The clear command guarantees that no trace data preceding the instant it is
+ * called will be in the resulting trace.
+ *
+ * Trace data produced from the moment it is called and when the
+ * function returned might be present in the resulting trace.
+ *
+ * Return 0 on success else a negative LTTng error code.
+ *
+ * Important error codes:
+ *    LTTNG_ERR_CLEAR_DISALLOWED_RELAY
+ *    LTTNG_ERR_CLEAR_NOT_AVAILABLE
+ *    LTTNG_ERR_CLEAR_NOT_AVAILABLE_RELAY
+ *    LTTNG_ERR_CLEAR_FAIL_CONSUMER
+*/
+extern int lttng_clear_session(const char *name);
+
 /*
  * Destroy a tracing session.
  *
  * The session will not be usable, tracing will be stopped thus buffers will be
  * flushed.
  *
+ * This call will wait for data availability for each domain of the session,
+ * which can take an arbitrary amount of time. However, when returning the
+ * tracing data is guaranteed to be ready to be read and analyzed.
+ *
+ * lttng_destroy_session_no_wait() may be used if such a guarantee is not
+ * needed.
+ *
  * The name can't be NULL here.
  *
  * Return 0 on success else a negative LTTng error code.
  */
 extern int lttng_destroy_session(const char *name);
 
+/*
+ * Behaves exactly like lttng_destroy_session but does not wait for data
+ * availability.
+ */
+extern int lttng_destroy_session_no_wait(const char *name);
+
 /*
  * List all the tracing sessions.
  *