Fix: lttng-sessiond: output stream metadata before events

[lttng-tools.git] / src / bin / lttng-sessiond / ust-metadata.cpp

diff --git a/src/bin/lttng-sessiond/ust-metadata.cpp b/src/bin/lttng-sessiond/ust-metadata.cpp
index d08cb40ae7f10ade8a8add223997a2e7aa884bed..566799efd08b2016e7ce24edeeadb3cd70937d04 100644 (file)
--- a/src/bin/lttng-sessiond/ust-metadata.cpp
+++ b/src/bin/lttng-sessiond/ust-metadata.cpp
@@ -15,6 +15,7 @@
 #include <inttypes.h>
 #include <common/common.hpp>
 #include <common/time.hpp>
+#include <vector>
 
 #include "ust-registry.hpp"
 #include "ust-clock.hpp"
@@ -841,6 +842,16 @@ int ust_metadata_event_statedump(struct ust_registry_session *session,
        if (chan->chan_id == -1U)
                return 0;
 
+       /*
+        * We don't want to output an event's metadata before its parent
+        * stream's metadata.  If the stream's metadata hasn't been output yet,
+        * skip this event.  Its metadata will be output when we output the
+        * stream's metadata.
+        */
+       if (!chan->metadata_dumped || event->metadata_dumped) {
+               return 0;
+       }
+
        ret = lttng_metadata_printf(session,
                "event {\n"
                "       name = \"%s\";\n"
@@ -951,6 +962,31 @@ int ust_metadata_channel_statedump(struct ust_registry_session *session,
        /* Flag success of metadata dump. */
        chan->metadata_dumped = 1;
 
+       /*
+        * Output the metadata of any existing event.
+        *
+        * Sort the events by id.  This is not necessary, but it's nice to have
+        * a more predictable order in the metadata file.
+        */
+       std::vector<ust_registry_event *> events;
+       {
+               cds_lfht_iter event_iter;
+               ust_registry_event *event;
+               cds_lfht_for_each_entry(chan->events->ht, &event_iter, event,
+                               node.node) {
+                       events.push_back(event);
+               }
+       }
+
+       std::sort(events.begin(), events.end(),
+               [] (ust_registry_event *a, ust_registry_event *b) {
+                       return a->id < b->id;
+               });
+
+       for (ust_registry_event *event : events) {
+               ust_metadata_event_statedump(session, chan, event);
+       }
+
        return 0;
 }