[Qemu-devel] [PATCH 1/3] monitor: split MonitorQAPIEventState

[marcandre.lureau@redhat.com]

From: Marc-André Lureau <marcandre.lureau@redhat.com>

Create a separate pending event structure MonitorQAPIEventPending.
Use a MonitorQAPIEventDelay callback to handle the delaying. This
allows other implementations of throttling.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
---
 monitor.c    | 124 +++++++++++++++++++++++++++++++++++++----------------------
 trace-events |   2 +-
 2 files changed, 79 insertions(+), 47 deletions(-)

diff --git a/monitor.c b/monitor.c
index fc32f12..0a6a16a 100644
--- a/monitor.c
+++ b/monitor.c
@@ -170,18 +170,27 @@ typedef struct {
     bool in_command_mode;       /* are we in command mode? */
 } MonitorQMP;
 
+typedef struct {
+    QAPIEvent event;    /* Event being tracked */
+    int64_t last;       /* QEMU_CLOCK_REALTIME value at last emission */
+    QEMUTimer *timer;   /* Timer for handling delayed events */
+    QObject *data;      /* Event pending delayed dispatch */
+} MonitorQAPIEventPending;
+
+typedef struct MonitorQAPIEventState MonitorQAPIEventState;
+
+typedef bool (*MonitorQAPIEventDelay) (MonitorQAPIEventState *evstate,
+                                       QDict *data);
 /*
  * To prevent flooding clients, events can be throttled. The
  * throttling is calculated globally, rather than per-Monitor
  * instance.
  */
-typedef struct MonitorQAPIEventState {
-    QAPIEvent event;    /* Event being tracked */
+struct MonitorQAPIEventState {
     int64_t rate;       /* Minimum time (in ns) between two events */
-    int64_t last;       /* QEMU_CLOCK_REALTIME value at last emission */
-    QEMUTimer *timer;   /* Timer for handling delayed events */
-    QObject *data;      /* Event pending delayed dispatch */
-} MonitorQAPIEventState;
+    MonitorQAPIEventDelay delay;
+    void *data;
+};
 
 struct Monitor {
     CharDriverState *chr;
@@ -452,6 +461,39 @@ static void monitor_qapi_event_emit(QAPIEvent event, QObject *data)
     }
 }
 
+static bool
+monitor_qapi_event_delay(MonitorQAPIEventState *evstate, QDict *data)
+{
+    int64_t now = qemu_clock_get_ns(QEMU_CLOCK_REALTIME);
+    MonitorQAPIEventPending *p = evstate->data;
+    int64_t delta = now - p->last;
+
+    /* Rate limit of 0 indicates no throttling */
+    if (!evstate->rate) {
+        p->last = now;
+        return false;
+    }
+
+    if (p->data || delta < evstate->rate) {
+        /* If there's an existing event pending, replace
+         * it with the new event, otherwise schedule a
+         * timer for delayed emission
+         */
+        if (p->data) {
+            qobject_decref(p->data);
+        } else {
+            int64_t then = p->last + evstate->rate;
+            timer_mod_ns(p->timer, then);
+        }
+        p->data = QOBJECT(data);
+        qobject_incref(p->data);
+        return true;
+    }
+
+    p->last = now;
+    return false;
+}
+
 /*
  * Queue a new event for emission to Monitor instances,
  * applying any rate limiting if required.
@@ -467,35 +509,15 @@ monitor_qapi_event_queue(QAPIEvent event, QDict *data, Error **errp)
     trace_monitor_protocol_event_queue(event,
                                        data,
                                        evstate->rate,
-                                       evstate->last,
                                        now);
 
-    /* Rate limit of 0 indicates no throttling */
     qemu_mutex_lock(&monitor_lock);
-    if (!evstate->rate) {
+
+    if (!evstate->delay ||
+        !evstate->delay(evstate, data)) {
         monitor_qapi_event_emit(event, QOBJECT(data));
-        evstate->last = now;
-    } else {
-        int64_t delta = now - evstate->last;
-        if (evstate->data ||
-            delta < evstate->rate) {
-            /* If there's an existing event pending, replace
-             * it with the new event, otherwise schedule a
-             * timer for delayed emission
-             */
-            if (evstate->data) {
-                qobject_decref(evstate->data);
-            } else {
-                int64_t then = evstate->last + evstate->rate;
-                timer_mod_ns(evstate->timer, then);
-            }
-            evstate->data = QOBJECT(data);
-            qobject_incref(evstate->data);
-        } else {
-            monitor_qapi_event_emit(event, QOBJECT(data));
-            evstate->last = now;
-        }
     }
+
     qemu_mutex_unlock(&monitor_lock);
 }
 
@@ -505,23 +527,37 @@ monitor_qapi_event_queue(QAPIEvent event, QDict *data, Error **errp)
  */
 static void monitor_qapi_event_handler(void *opaque)
 {
-    MonitorQAPIEventState *evstate = opaque;
+    MonitorQAPIEventPending *p = opaque;
     int64_t now = qemu_clock_get_ns(QEMU_CLOCK_REALTIME);
 
-    trace_monitor_protocol_event_handler(evstate->event,
-                                         evstate->data,
-                                         evstate->last,
+    trace_monitor_protocol_event_handler(p->event,
+                                         p->data,
+                                         p->last,
                                          now);
     qemu_mutex_lock(&monitor_lock);
-    if (evstate->data) {
-        monitor_qapi_event_emit(evstate->event, evstate->data);
-        qobject_decref(evstate->data);
-        evstate->data = NULL;
+    if (p->data) {
+        monitor_qapi_event_emit(p->event, p->data);
+        qobject_decref(p->data);
+        p->data = NULL;
     }
-    evstate->last = now;
+    p->last = now;
     qemu_mutex_unlock(&monitor_lock);
 }
 
+static MonitorQAPIEventPending *
+monitor_qapi_event_pending_new(QAPIEvent event)
+{
+    MonitorQAPIEventPending *p;
+
+    p = g_new0(MonitorQAPIEventPending, 1);
+    p->event = event;
+    p->timer = timer_new(QEMU_CLOCK_REALTIME,
+                         SCALE_MS,
+                         monitor_qapi_event_handler,
+                         p);
+    return p;
+}
+
 /*
  * @event: the event ID to be limited
  * @rate: the rate limit in milliseconds
@@ -539,15 +575,11 @@ monitor_qapi_event_throttle(QAPIEvent event, int64_t rate)
     evstate = &(monitor_qapi_event_state[event]);
 
     trace_monitor_protocol_event_throttle(event, rate);
-    evstate->event = event;
     assert(rate * SCALE_MS <= INT64_MAX);
     evstate->rate = rate * SCALE_MS;
-    evstate->last = 0;
-    evstate->data = NULL;
-    evstate->timer = timer_new(QEMU_CLOCK_REALTIME,
-                               SCALE_MS,
-                               monitor_qapi_event_handler,
-                               evstate);
+
+    evstate->delay = monitor_qapi_event_delay;
+    evstate->data = monitor_qapi_event_pending_new(event);
 }
 
 static void monitor_qapi_event_init(void)
diff --git a/trace-events b/trace-events
index 8f9614a..b1ea596 100644
--- a/trace-events
+++ b/trace-events
@@ -1028,7 +1028,7 @@ handle_qmp_command(void *mon, const char *cmd_name) "mon %p cmd_name \"%s\""
 monitor_protocol_emitter(void *mon) "mon %p"
 monitor_protocol_event_handler(uint32_t event, void *data, uint64_t last, uint64_t now) "event=%d data=%p last=%" PRId64 " now=%" PRId64
 monitor_protocol_event_emit(uint32_t event, void *data) "event=%d data=%p"
-monitor_protocol_event_queue(uint32_t event, void *data, uint64_t rate, uint64_t last, uint64_t now) "event=%d data=%p rate=%" PRId64 " last=%" PRId64 " now=%" PRId64
+monitor_protocol_event_queue(uint32_t event, void *data, uint64_t rate, uint64_t now) "event=%d data=%p rate=%" PRId64 " now=%" PRId64
 monitor_protocol_event_throttle(uint32_t event, uint64_t rate) "event=%d rate=%" PRId64
 
 # hw/net/opencores_eth.c
-- 
2.4.3