add heartbeat_fire_on_set variable to fire heartbeat instantly when its first…

add heartbeat_fire_on_set variable to fire heartbeat instantly when its first enabled (legacy behavior)

src/switch_core_session.c

@@ -1524,9 +1524,16 @@ SWITCH_DECLARE(void) switch_core_session_unsched_heartbeat(switch_core_session_t
 
 SWITCH_DECLARE(void) switch_core_session_sched_heartbeat(switch_core_session_t *session, uint32_t seconds)
 {
+	time_t when;
 
 	switch_core_session_unsched_heartbeat(session);
-	session->track_id = switch_scheduler_add_task(switch_epoch_time_now(NULL) + session->track_duration, sch_heartbeat_callback, (char *) __SWITCH_FUNC__,
+	if (switch_true(switch_channel_get_variable(session->channel, "heartbeat_fire_on_set"))) {
+		when = switch_epoch_time_now(NULL);
+	} else {
+		when = switch_epoch_time_now(NULL) + session->track_duration;
+	}
+
+	session->track_id = switch_scheduler_add_task(when, sch_heartbeat_callback, (char *) __SWITCH_FUNC__,
 												  switch_core_session_get_uuid(session), 0, strdup(switch_core_session_get_uuid(session)), SSHF_FREE_ARG);
 }
 
@@ -1550,8 +1557,11 @@ SWITCH_DECLARE(void) switch_core_session_enable_heartbeat(switch_core_session_t
 		return;
 	}
 
-	session->read_frame_count = (session->read_impl.samples_per_second / session->read_impl.samples_per_packet) * seconds;
-
+	if (switch_true(switch_channel_get_variable(session->channel, "heartbeat_fire_on_set"))) {
+		session->read_frame_count = 0;
+	} else {
+		session->read_frame_count = (session->read_impl.samples_per_second / session->read_impl.samples_per_packet) * seconds;
+	}
 
 	switch_core_session_unsched_heartbeat(session);