Add 'query-events' command to QMP to query async events

Sometimes it is neccessary for an application to determine
whether a particular QMP event is available, so they can
decide whether to use compatibility code instead. This
introduces a new 'query-events' command to QMP to do just
that

 { "execute": "query-events" }
 {"return": [{"name": "WAKEUP"},
             {"name": "SUSPEND"},
             {"name": "DEVICE_TRAY_MOVED"},
             {"name": "BLOCK_JOB_CANCELLED"},
             {"name": "BLOCK_JOB_COMPLETED"},
             ...snip...
             {"name": "SHUTDOWN"}]}

* monitor.c: Turn MonitorEvent -> string conversion
  into a lookup from a static table of constant strings.
  Add impl of qmp_query_events monitor command handler
* qapi-schema.json, qmp-commands.hx: Define contract of
  query-events command

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>

1 files changed, 22 insertions, 0 deletions

diff --git a/qapi-schema.json b/qapi-schema.json
index bb1f806532..3b6e3468b4 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -228,6 +228,28 @@
 { 'command': 'query-commands', 'returns': ['CommandInfo'] }
 
 ##
+# @EventInfo:
+#
+# Information about a QMP event
+#
+# @name: The event name
+#
+# Since: 1.2.0
+##
+{ 'type': 'EventInfo', 'data': {'name': 'str'} }
+
+##
+# @query-events:
+#
+# Return a list of supported QMP events by this server
+#
+# Returns: A list of @EventInfo for all supported events
+#
+# Since: 1.2.0
+##
+{ 'command': 'query-events', 'returns': ['EventInfo'] }
+
+##
 # @MigrationStats
 #
 # Detailed migration status.