Update lttng_clear_session relevant error code return

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

diff --git a/include/lttng/session.h b/include/lttng/session.h
index e0594d2e82e452bf072d90899b945b2afc31be3c..a73c7a2580376152837f8d779c141688bbcb0ca9 100644 (file)
--- a/include/lttng/session.h
+++ b/include/lttng/session.h
@@ -32,7 +32,7 @@ extern "C" {
  */
 #define LTTNG_SESSION_PADDING1             12
 struct lttng_session {
-       char name[NAME_MAX];
+       char name[LTTNG_NAME_MAX];
        /* The path where traces are written */
        char path[PATH_MAX];
        uint32_t enabled;       /* enabled/started: 1, disabled/stopped: 0 */
@@ -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_RELAY_DISALLOW
+ *    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.
  *