This removes the need for using monitor_is_qmp() to check the
subclass type, which is an anti-pattern.

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Tested-by: Peter Krempa <pkrempa@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
---
 include/monitor/monitor.h  |  1 +
 monitor/monitor-internal.h |  5 +++++
 monitor/monitor.c          | 15 +++------------
 monitor/qmp.c              | 20 ++++++++++++++++++++
 4 files changed, 29 insertions(+), 12 deletions(-)

diff --git a/include/monitor/monitor.h b/include/monitor/monitor.h
index bfbeedec9b..821465f17e 100644
--- a/include/monitor/monitor.h
+++ b/include/monitor/monitor.h
@@ -3,6 +3,7 @@
 
 #include "block/block.h"
 #include "qapi/qapi-types-misc.h"
+#include "qapi/qapi-emit-events.h"
 #include "qemu/readline.h"
 #include "exec/hwaddr.h"
 #include "qom/object.h"
diff --git a/monitor/monitor-internal.h b/monitor/monitor-internal.h
index 23cef68153..763b5c9625 100644
--- a/monitor/monitor-internal.h
+++ b/monitor/monitor-internal.h
@@ -111,6 +111,11 @@ struct MonitorClass {
      */
     int (*vprintf)(Monitor *mon, const char *fmt, va_list ap)
         G_GNUC_PRINTF(2, 0);
+    /*
+     * If non-NULL, the monitor is able to send event
+     * notifications back to the client
+     */
+    void (*emit_event)(Monitor *mon, QAPIEvent event, QDict *qdict);
 };
 
 struct Monitor {
diff --git a/monitor/monitor.c b/monitor/monitor.c
index 0cb0930bf4..90cfb59c66 100644
--- a/monitor/monitor.c
+++ b/monitor/monitor.c
@@ -348,22 +348,13 @@ static inline QEMUClockType monitor_get_event_clock(void)
 static void monitor_qapi_event_emit(QAPIEvent event, QDict *qdict)
 {
     Monitor *mon;
-    MonitorQMP *qmp_mon;
 
     trace_monitor_protocol_event_emit(event, qdict);
     QTAILQ_FOREACH(mon, &mon_list, entry) {
-        if (!monitor_is_qmp(mon)) {
-            continue;
+        MonitorClass *cls = MONITOR_GET_CLASS(mon);
+        if (cls->emit_event) {
+            cls->emit_event(mon, event, qdict);
         }
-
-        qmp_mon = container_of(mon, MonitorQMP, parent_obj);
-        {
-            QEMU_LOCK_GUARD(&mon->mon_lock);
-            if (qmp_mon->commands == &qmp_cap_negotiation_commands) {
-                continue;
-            }
-        }
-        qmp_send_response(qmp_mon, qdict);
     }
 }
 
diff --git a/monitor/qmp.c b/monitor/qmp.c
index 3574b9a339..d732fff9a3 100644
--- a/monitor/qmp.c
+++ b/monitor/qmp.c
@@ -99,11 +99,17 @@ static void monitor_qmp_set_pretty(Object *obj, bool val, Error **errp)
     mon->pretty = val;
 }
 
+static void monitor_qmp_emit_event(Monitor *mon, QAPIEvent event, QDict *qdict);
+
 static void monitor_qmp_class_init(ObjectClass *cls, const void *data)
 {
+    MonitorClass *moncls = MONITOR_CLASS(cls);
+
     object_class_property_add_bool(cls, "pretty",
                                    monitor_qmp_get_pretty,
                                    monitor_qmp_set_pretty);
+
+    moncls->emit_event = monitor_qmp_emit_event;
 }
 
 static void handle_qmp_command(void *opaque, QObject *req, Error *err);
@@ -117,6 +123,20 @@ static void monitor_qmp_init(Object *obj)
     json_message_parser_init(&mon->parser, handle_qmp_command, mon, NULL);
 }
 
+static void monitor_qmp_emit_event(Monitor *mon, QAPIEvent event, QDict *qdict)
+{
+    MonitorQMP *qmp = MONITOR_QMP(mon);
+
+    WITH_QEMU_LOCK_GUARD(&mon->mon_lock) {
+        if (qmp->commands == &qmp_cap_negotiation_commands) {
+            return;
+        }
+    }
+
+    qmp_send_response(qmp, qdict);
+}
+
+
 static bool qmp_oob_enabled(MonitorQMP *mon)
 {
     return mon->capab[QMP_CAPABILITY_OOB];
-- 
2.55.0