monitor: rename *_pop_one to *_pop_any

The old names are confusing since both of the old functions are popping
an item from multiple queues rather than a single queue.  In that
sense, *_pop_any() suites better than *_pop_one().

Since at it, touch up the function monitor_qmp_response_pop_any() a bit
to let the callers pass in a QMPResponse struct instead of returning a
struct.  Change the return value to boolean to mark whether we have
popped a valid response instead.

Suggested-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20180620073223.31964-3-peterx@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
diff --git a/monitor.c b/monitor.c
index 7b473aa..2881345 100644
--- a/monitor.c
+++ b/monitor.c
@@ -542,10 +542,10 @@
 typedef struct QMPResponse QMPResponse;
 
 /*
- * Return one QMPResponse.  The response is only valid if
- * response.data is not NULL.
+ * Pop a QMPResponse from any monitor's response queue into @response.
+ * Return false if all the queues are empty; else true.
  */
-static QMPResponse monitor_qmp_response_pop_one(void)
+static bool monitor_qmp_response_pop_any(QMPResponse *response)
 {
     Monitor *mon;
     QObject *data = NULL;
@@ -556,22 +556,20 @@
         data = g_queue_pop_head(mon->qmp.qmp_responses);
         qemu_mutex_unlock(&mon->qmp.qmp_queue_lock);
         if (data) {
+            response->mon = mon;
+            response->data = data;
             break;
         }
     }
     qemu_mutex_unlock(&monitor_lock);
-    return (QMPResponse) { .mon = mon, .data = data };
+    return data != NULL;
 }
 
 static void monitor_qmp_bh_responder(void *opaque)
 {
     QMPResponse response;
 
-    while (true) {
-        response = monitor_qmp_response_pop_one();
-        if (!response.data) {
-            break;
-        }
+    while (monitor_qmp_response_pop_any(&response)) {
         monitor_json_emitter_raw(response.mon, response.data);
         qobject_unref(response.data);
     }
@@ -4199,7 +4197,7 @@
  * when we process one request on a specific monitor, we put that
  * monitor to the end of mon_list queue.
  */
-static QMPRequest *monitor_qmp_requests_pop_one(void)
+static QMPRequest *monitor_qmp_requests_pop_any(void)
 {
     QMPRequest *req_obj = NULL;
     Monitor *mon;
@@ -4231,7 +4229,7 @@
 
 static void monitor_qmp_bh_dispatcher(void *data)
 {
-    QMPRequest *req_obj = monitor_qmp_requests_pop_one();
+    QMPRequest *req_obj = monitor_qmp_requests_pop_any();
 
     if (req_obj) {
         trace_monitor_qmp_cmd_in_band(qobject_get_try_str(req_obj->id) ?: "");