Wait for data availability when stopping a session

[lttng-tools.git] / src / lib / lttng-ctl / lttng-ctl.c

diff --git a/src/lib/lttng-ctl/lttng-ctl.c b/src/lib/lttng-ctl/lttng-ctl.c
index edaebf59c8654515ac7872d0888e4a84dd6ab0ad..67c5972191016d8eafbf74d1e34faea0e8221e7f 100644 (file)
--- a/src/lib/lttng-ctl/lttng-ctl.c
+++ b/src/lib/lttng-ctl/lttng-ctl.c
@@ -69,8 +69,6 @@ static int connected;
  * Those two variables are used by error.h to silent or control the verbosity of
  * error message. They are global to the library so application linking with it
  * are able to compile correctly and also control verbosity of the library.
- *
- * Note that it is *not* possible to silent ERR() and PERROR() macros.
  */
 int lttng_opt_quiet;
 int lttng_opt_verbose;
@@ -682,11 +680,11 @@ int lttng_start_tracing(const char *session_name)
 }
 
 /*
- *  Stop tracing for all traces of the session.
- *  Returns size of returned session payload data or a negative error code.
+ * Stop tracing for all traces of the session.
  */
-int lttng_stop_tracing(const char *session_name)
+static int _lttng_stop_tracing(const char *session_name, int wait)
 {
+       int ret, data_ret;
        struct lttcomm_session_msg lsm;
 
        if (session_name == NULL) {
@@ -697,7 +695,57 @@ int lttng_stop_tracing(const char *session_name)
 
        copy_string(lsm.session.name, session_name, sizeof(lsm.session.name));
 
-       return ask_sessiond(&lsm, NULL);
+       ret = ask_sessiond(&lsm, NULL);
+       if (ret < 0 && ret != -LTTNG_ERR_TRACE_ALREADY_STOPPED) {
+               goto error;
+       }
+
+       if (!wait) {
+               goto end;
+       }
+
+       _MSG("Waiting for data availability");
+
+       /* Check for data availability */
+       do {
+               data_ret = lttng_data_available(session_name);
+               if (data_ret < 0) {
+                       /* Return the data available call error. */
+                       ret = data_ret;
+                       goto error;
+               }
+
+               /*
+                * Data sleep time before retrying (in usec). Don't sleep if the call
+                * returned value indicates availability.
+                */
+               if (!data_ret) {
+                       usleep(DEFAULT_DATA_AVAILABILITY_WAIT_TIME);
+                       _MSG(".");
+               }
+       } while (data_ret != 1);
+
+       MSG("");
+
+end:
+error:
+       return ret;
+}
+
+/*
+ * Stop tracing and wait for data availability.
+ */
+int lttng_stop_tracing(const char *session_name)
+{
+       return _lttng_stop_tracing(session_name, 1);
+}
+
+/*
+ * Stop tracing but _don't_ wait for data availability.
+ */
+int lttng_stop_tracing_no_wait(const char *session_name)
+{
+       return _lttng_stop_tracing(session_name, 0);
 }
 
 /*
@@ -1590,6 +1638,38 @@ int _lttng_create_session_ext(const char *name, const char *url,
                        NULL);
 }
 
+/*
+ * 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.
+ */
+int lttng_data_available(const char *session_name)
+{
+       int ret;
+       struct lttcomm_session_msg lsm;
+
+       if (session_name == NULL) {
+               return -LTTNG_ERR_INVALID;
+       }
+
+       lsm.cmd_type = LTTNG_DATA_AVAILABLE;
+
+       copy_string(lsm.session.name, session_name, sizeof(lsm.session.name));
+
+       ret = ask_sessiond(&lsm, NULL);
+
+       /*
+        * The ask_sessiond function negate the return code if it's not LTTNG_OK so
+        * getting -1 means that the reply ret_code was 1 thus meaning that the
+        * data is available. Yes it is hackish but for now this is the only way.
+        */
+       if (ret == -1) {
+               ret = 1;
+       }
+
+       return ret;
+}
+
 /*
  * lib constructor
  */