qtest: Reintroduce qtest_qmp_receive with QMP event buffering

The new qtest_qmp_receive buffers all the received qmp events, allowing
qtest_qmp_eventwait_ref to return them.

This is intended to solve the race in regard to ordering of qmp events
vs qmp responses, as soon as the callers start using the new interface.

In addition to that, define qtest_qmp_event_ref a function which only scans
the buffer that qtest_qmp_receive stores the events to.  This is intended
for callers that are only interested in events that were received during
the last call to the qtest_qmp_receive.

Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20201006123904.610658-3-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/tests/qtest/libqos/libqtest.h b/tests/qtest/libqos/libqtest.h
index 9b3f99b322307dcfeb9ff4c38be1fd29c1436803..b7a776068c76965981a07e34ef08ae40d0f34f93 100644 (file)
--- a/tests/qtest/libqos/libqtest.h
+++ b/tests/qtest/libqos/libqtest.h
@@ -198,6 +198,16 @@ void qtest_qmp_vsend(QTestState *s, const char *fmt, va_list ap)
  */
 QDict *qtest_qmp_receive_dict(QTestState *s);
 
+/**
+ * qtest_qmp_receive:
+ * @s: #QTestState instance to operate on.
+ *
+ * Reads a QMP message from QEMU and returns the response.
+ * Buffers all the events received meanwhile, until a
+ * call to qtest_qmp_eventwait
+ */
+QDict *qtest_qmp_receive(QTestState *s);
+
 /**
  * qtest_qmp_eventwait:
  * @s: #QTestState instance to operate on.
@@ -217,6 +227,19 @@ void qtest_qmp_eventwait(QTestState *s, const char *event);
  */
 QDict *qtest_qmp_eventwait_ref(QTestState *s, const char *event);
 
+/**
+ * qtest_qmp_event_ref:
+ * @s: #QTestState instance to operate on.
+ * @event: event to return.
+ *
+ * Removes non-matching events from the buffer that was set by
+ * qtest_qmp_receive, until an event bearing the given name is found,
+ * and returns it.
+ * If no event matches, clears the buffer and returns NULL.
+ *
+ */
+QDict *qtest_qmp_event_ref(QTestState *s, const char *event);
+
 /**
  * qtest_qmp_receive_success:
  * @s: #QTestState instance to operate on

diff --git a/tests/qtest/libqtest.c b/tests/qtest/libqtest.c
index dadc46582571d5f9c82cdb3e693d51c4569591f6..d4c49a52fff79dc71220d66d74564769f08d6049 100644 (file)
--- a/tests/qtest/libqtest.c
+++ b/tests/qtest/libqtest.c
@@ -63,6 +63,7 @@ struct QTestState
     bool irq_level[MAX_IRQ];
     GString *rx;
     QTestTransportOps ops;
+    GList *pending_events;
 };
 
 static GHookList abrt_hooks;
@@ -279,6 +280,7 @@ QTestState *qtest_init_without_qmp_handshake(const char *extra_args)
 
     g_test_message("starting QEMU: %s", command);
 
+    s->pending_events = NULL;
     s->wstatus = 0;
     s->expected_status = 0;
     s->qemu_pid = fork();
@@ -386,6 +388,13 @@ void qtest_quit(QTestState *s)
     close(s->fd);
     close(s->qmp_fd);
     g_string_free(s->rx, true);
+
+    for (GList *it = s->pending_events; it != NULL; it = it->next) {
+        qobject_unref((QDict *)it->data);
+    }
+
+    g_list_free(s->pending_events);
+
     g_free(s);
 }
 
@@ -603,6 +612,19 @@ QDict *qmp_fd_receive(int fd)
     return qmp.response;
 }
 
+QDict *qtest_qmp_receive(QTestState *s)
+{
+    while (true) {
+        QDict *response = qtest_qmp_receive_dict(s);
+
+        if (!qdict_get_try_str(response, "event")) {
+            return response;
+        }
+        /* Stash the event for a later consumption */
+        s->pending_events = g_list_prepend(s->pending_events, response);
+    }
+}
+
 QDict *qtest_qmp_receive_dict(QTestState *s)
 {
     return qmp_fd_receive(s->qmp_fd);
@@ -771,10 +793,34 @@ void qtest_qmp_send_raw(QTestState *s, const char *fmt, ...)
     va_end(ap);
 }
 
-QDict *qtest_qmp_eventwait_ref(QTestState *s, const char *event)
+QDict *qtest_qmp_event_ref(QTestState *s, const char *event)
 {
+    GList *next = NULL;
     QDict *response;
 
+    for (GList *it = s->pending_events; it != NULL; it = next) {
+
+        next = it->next;
+        response = (QDict *)it->data;
+
+        s->pending_events = g_list_remove_link(s->pending_events, it);
+
+        if (!strcmp(qdict_get_str(response, "event"), event)) {
+            return response;
+        }
+        qobject_unref(response);
+    }
+    return NULL;
+}
+
+QDict *qtest_qmp_eventwait_ref(QTestState *s, const char *event)
+{
+    QDict *response = qtest_qmp_event_ref(s, event);
+
+    if (response) {
+        return response;
+    }
+
     for (;;) {
         response = qtest_qmp_receive_dict(s);
         if ((qdict_haskey(response, "event")) &&
@@ -1403,6 +1449,7 @@ QTestState *qtest_inproc_init(QTestState **s, bool log, const char* arch,
 {
     QTestState *qts;
     qts = g_new0(QTestState, 1);
+    qts->pending_events = NULL;
     *s = qts; /* Expose qts early on, since the query endianness relies on it */
     qts->wstatus = 0;
     for (int i = 0; i < MAX_IRQ; i++) {