[Qemu-devel] [RFC 5/6] monitor: Throttle event VSERPORT_CHANGE separately by "id"

[Markus Armbruster <armbru@redhat.com>]

VSERPORT_CHANGE is emitted when the guest opens or closes a
virtio-serial port.  The event's member "id" identifies the port.

When several events arrive quickly, throttling drops all but the last
of them.  Because of that, a QMP client must assume that *any* port
may have changed state when it receives a VSERPORT_CHANGE event and
throttling may have happened.

Make the event more useful by throttling it for each port separately.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
---
 monitor.c | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/monitor.c b/monitor.c
index 9807a5b..7e21407 100644
--- a/monitor.c
+++ b/monitor.c
@@ -567,8 +567,13 @@ static void monitor_qapi_event_handler(void *opaque)
 static unsigned int qapi_event_throttle_hash(const void *key)
 {
     const MonitorQAPIEventState *evstate = key;
+    unsigned int hash = evstate->event * 255;
 
-    return evstate->event * 255;
+    if (evstate->event == QAPI_EVENT_VSERPORT_CHANGE) {
+        hash += g_str_hash(qdict_get_str(evstate->qdict, "id"));
+    }
+
+    return hash;
 }
 
 static gboolean qapi_event_throttle_equal(const void *a, const void *b)
@@ -576,7 +581,16 @@ static gboolean qapi_event_throttle_equal(const void *a, const void *b)
     const MonitorQAPIEventState *eva = a;
     const MonitorQAPIEventState *evb = b;
 
-    return eva->event == evb->event;
+    if (eva->event != evb->event) {
+        return FALSE;
+    }
+
+    if (eva->event == QAPI_EVENT_VSERPORT_CHANGE) {
+        return !strcmp(qdict_get_str(eva->qdict, "id"),
+                       qdict_get_str(evb->qdict, "id"));
+    }
+
+    return TRUE;
 }
 
 static void monitor_qapi_event_init(void)
-- 
2.4.3