Originally QMP is going throw these steps:
JSON Parser --> QMP Dispatcher --> Respond
/|\ (2) (3) |
(1) | \|/ (4)
+--------- main thread --------+
This patch does this:
JSON Parser QMP Dispatcher --> Respond
/|\ | /|\ (4) |
| | (2) | (3) | (5)
(1) | +-----> | \|/
+--------- main thread <-------+
So the parsing job and the dispatching job is isolated now. It gives us
a chance in following up patches to totally move the parser outside.
The isloation is done using one QEMUBH. Only one dispatcher BH for all
the monitors.
Signed-off-by: Peter Xu <pet...@redhat.com>
---
monitor.c | 122 ++++++++++++++++++++++++++++++++++++++++++++++++++------------
1 file changed, 99 insertions(+), 23 deletions(-)
diff --git a/monitor.c b/monitor.c
index aa0c384..f649d6a 100644
--- a/monitor.c
+++ b/monitor.c
@@ -213,6 +213,10 @@ struct MonitorGlobal {
QemuThread mon_io_thread;
GMainContext *mon_context;
GMainLoop *mon_loop;
+ /* Bottom half to dispatch the requests received from IO thread */
+ QEMUBH *qmp_dispatcher_bh;
+ /* Input queue that hangs all the parsed QMP requests */
+ GQueue *qmp_requests;
};
static struct MonitorGlobal mon_global;
@@ -3858,29 +3862,31 @@ static void monitor_qmp_respond(Monitor *mon, QObject
*rsp,
qobject_decref(rsp);
}
-static void handle_qmp_command(JSONMessageParser *parser, GQueue *tokens,
- void *opaque)
+struct QMPRequest {
+ /* Owner of the request */
+ Monitor *mon;
+ /* "id" field of the request */
+ QObject *id;
+ /* Request object to be handled */
+ QObject *req;
+};
+typedef struct QMPRequest QMPRequest;
+
+/*
+ * Dispatch one single QMP request. The function will free the req_obj
+ * and objects inside it before return.
+ */
+static void monitor_qmp_dispatch_one(QMPRequest *req_obj)
{
- QObject *req, *rsp = NULL, *id = NULL;
+ Monitor *mon, *old_mon;
+ QObject *req, *rsp = NULL, *id;
QDict *qdict = NULL;
- Monitor *mon = opaque, *old_mon;
- Error *err = NULL;
- req = json_parser_parse_err(tokens, NULL, &err);
- if (!req && !err) {
- /* json_parser_parse_err() sucks: can fail without setting @err */
- error_setg(&err, QERR_JSON_PARSING);
- }
- if (err) {
- goto err_out;
- }
+ req = req_obj->req;
+ mon = req_obj->mon;
+ id = req_obj->id;
- qdict = qobject_to_qdict(req);
- if (qdict) {
- id = qdict_get(qdict, "id");
- qobject_incref(id);
- qdict_del(qdict, "id");
- } /* else will fail qmp_dispatch() */
+ g_free(req_obj);
if (trace_event_get_state_backends(TRACE_HANDLE_QMP_COMMAND)) {
QString *req_json = qobject_to_json(req);
@@ -3891,7 +3897,7 @@ static void handle_qmp_command(JSONMessageParser *parser,
GQueue *tokens,
old_mon = cur_mon;
cur_mon = mon;
- rsp = qmp_dispatch(cur_mon->qmp.commands, req);
+ rsp = qmp_dispatch(mon->qmp.commands, req);
cur_mon = old_mon;
@@ -3907,12 +3913,66 @@ static void handle_qmp_command(JSONMessageParser
*parser, GQueue *tokens,
}
}
-err_out:
- monitor_qmp_respond(mon, rsp, err, id);
-
+ /* Respond if necessary */
+ monitor_qmp_respond(mon, rsp, NULL, id);
qobject_decref(req);
}
+static void monitor_qmp_bh_dispatcher(void *data)
+{
+ QMPRequest *req_obj;
+
+ while (true) {
+ req_obj = g_queue_pop_head(mon_global.qmp_requests);
+ if (!req_obj) {
+ break;
+ }
+ monitor_qmp_dispatch_one(req_obj);
+ }
+}
+
+static void handle_qmp_command(JSONMessageParser *parser, GQueue *tokens,
+ void *opaque)
+{
+ QObject *req, *id = NULL;
+ QDict *qdict = NULL;
+ Monitor *mon = opaque;
+ Error *err = NULL;
+ QMPRequest *req_obj;
+
+ req = json_parser_parse_err(tokens, NULL, &err);
+ if (!req && !err) {
+ /* json_parser_parse_err() sucks: can fail without setting @err */
+ error_setg(&err, QERR_JSON_PARSING);
+ }
+ if (err) {
+ monitor_qmp_respond(mon, NULL, err, NULL);
+ qobject_decref(req);
+ }
+
+ qdict = qobject_to_qdict(req);
+ if (qdict) {
+ id = qdict_get(qdict, "id");
+ qobject_incref(id);
+ qdict_del(qdict, "id");
+ } /* else will fail qmp_dispatch() */
+
+ req_obj = g_new0(QMPRequest, 1);
+ req_obj->mon = mon;
+ req_obj->id = id;
+ req_obj->req = req;
+
+ /*
+ * Put the request to the end of queue so that requests will be
+ * handled in time order. Ownership for req_obj, req, id,
+ * etc. will be delivered to the handler side.
+ */
+ g_queue_push_tail(mon_global.qmp_requests, req_obj);
+
+ /* Kick the dispatcher routine */
+ qemu_bh_schedule(mon_global.qmp_dispatcher_bh);
+}
+
static void monitor_qmp_read(void *opaque, const uint8_t *buf, int size)
{
Monitor *mon = opaque;
@@ -4085,6 +4145,16 @@ static void monitor_io_thread_init(void)
mon_global.mon_loop = g_main_loop_new(mon_global.mon_context, TRUE);
qemu_thread_create(&mon_global.mon_io_thread, "mon-io-thr",
monitor_io_thread, NULL, QEMU_THREAD_JOINABLE);
+
+ /*
+ * This MUST be on main loop thread since we have commands that
+ * have assumption to be run on main loop thread (Yeah, we'd
+ * better remove this assumption in the future).
+ */
+ mon_global.qmp_dispatcher_bh = aio_bh_new(qemu_get_aio_context(),
+ monitor_qmp_bh_dispatcher,
+ NULL);
+ mon_global.qmp_requests = g_queue_new();
}
void monitor_init_globals(void)
@@ -4213,6 +4283,12 @@ void monitor_cleanup(void)
qemu_mutex_unlock(&monitor_lock);
monitor_io_thread_destroy();
+
+ qemu_bh_delete(mon_global.qmp_dispatcher_bh);
+ mon_global.qmp_dispatcher_bh = NULL;
+
+ g_queue_free(mon_global.qmp_requests);
+ mon_global.qmp_requests = NULL;
}
QemuOptsList qemu_mon_opts = {
--
2.7.4
