Re: [Qemu-devel] [PATCH] tests: make filemonitor test more robust to event ordering

[Wei Yang]

On Wed, Aug 21, 2019 at 04:53:27PM +0100, Daniel P. Berrangé wrote:
>The ordering of events that are emitted during the rmdir
>test have changed with kernel >= 5.3. Semantically both
>new & old orderings are correct, so we must be able to
>cope with either.
>
>To cope with this, when we see an unexpected event, we
>push it back onto the queue and look and the subsequent
>event to see if that matches instead.
>
>Signed-off-by: Daniel P. Berrangé <address@hidden>

Tested-by: Wei Yang <address@hidden>

>---
> tests/test-util-filemonitor.c | 43 +++++++++++++++++++++++++++--------
> 1 file changed, 34 insertions(+), 9 deletions(-)
>
>diff --git a/tests/test-util-filemonitor.c b/tests/test-util-filemonitor.c
>index 46e781c022..301cd2db61 100644
>--- a/tests/test-util-filemonitor.c
>+++ b/tests/test-util-filemonitor.c
>@@ -45,6 +45,11 @@ typedef struct {
>     const char *filedst;
>     int64_t *watchid;
>     int eventid;
>+    /*
>+     * Only valid with OP_EVENT - this event might be
>+     * swapped with the next OP_EVENT
>+     */
>+    bool swapnext;
> } QFileMonitorTestOp;
> 
> typedef struct {
>@@ -98,6 +103,10 @@ qemu_file_monitor_test_handler(int64_t id,
>     QFileMonitorTestData *data = opaque;
>     QFileMonitorTestRecord *rec = g_new0(QFileMonitorTestRecord, 1);
> 
>+    if (debug) {
>+        g_printerr("Queue event id %" PRIx64 " event %d file %s\n",
>+                   id, event, filename);
>+    }
>     rec->id = id;
>     rec->event = event;
>     rec->filename = g_strdup(filename);
>@@ -125,7 +134,8 @@ qemu_file_monitor_test_record_free(QFileMonitorTestRecord 
>*rec)
>  * to wait for the event to be queued for us.
>  */
> static QFileMonitorTestRecord *
>-qemu_file_monitor_test_next_record(QFileMonitorTestData *data)
>+qemu_file_monitor_test_next_record(QFileMonitorTestData *data,
>+                                   QFileMonitorTestRecord *pushback)
> {
>     GTimer *timer = g_timer_new();
>     QFileMonitorTestRecord *record = NULL;
>@@ -139,9 +149,15 @@ qemu_file_monitor_test_next_record(QFileMonitorTestData 
>*data)
>     }
>     if (data->records) {
>         record = data->records->data;
>-        tmp = data->records;
>-        data->records = g_list_remove_link(data->records, tmp);
>-        g_list_free(tmp);
>+        if (pushback) {
>+            data->records->data = pushback;
>+        } else {
>+            tmp = data->records;
>+            data->records = g_list_remove_link(data->records, tmp);
>+            g_list_free(tmp);
>+        }
>+    } else if (pushback) {
>+        qemu_file_monitor_test_record_free(pushback);
>     }
>     qemu_mutex_unlock(&data->lock);
> 
>@@ -158,13 +174,15 @@ static bool
> qemu_file_monitor_test_expect(QFileMonitorTestData *data,
>                               int64_t id,
>                               QFileMonitorEvent event,
>-                              const char *filename)
>+                              const char *filename,
>+                              bool swapnext)
> {
>     QFileMonitorTestRecord *rec;
>     bool ret = false;
> 
>-    rec = qemu_file_monitor_test_next_record(data);
>+    rec = qemu_file_monitor_test_next_record(data, NULL);
> 
>+ retry:
>     if (!rec) {
>         g_printerr("Missing event watch id %" PRIx64 " event %d file %s\n",
>                    id, event, filename);
>@@ -172,6 +190,11 @@ qemu_file_monitor_test_expect(QFileMonitorTestData *data,
>     }
> 
>     if (id != rec->id) {
>+        if (swapnext) {
>+            rec = qemu_file_monitor_test_next_record(data, rec);
>+            swapnext = false;
>+            goto retry;
>+        }
>         g_printerr("Expected watch id %" PRIx64 " but got %" PRIx64 "\n",
>                    id, rec->id);
>         goto cleanup;
>@@ -347,7 +370,8 @@ test_file_monitor_events(void)
>           .filesrc = "fish", },
>         { .type = QFILE_MONITOR_TEST_OP_EVENT,
>           .filesrc = "", .watchid = &watch4,
>-          .eventid = QFILE_MONITOR_EVENT_IGNORED },
>+          .eventid = QFILE_MONITOR_EVENT_IGNORED,
>+          .swapnext = true },
>         { .type = QFILE_MONITOR_TEST_OP_EVENT,
>           .filesrc = "fish", .watchid = &watch0,
>           .eventid = QFILE_MONITOR_EVENT_DELETED },
>@@ -493,8 +517,9 @@ test_file_monitor_events(void)
>                 g_printerr("Event id=%" PRIx64 " event=%d file=%s\n",
>                            *op->watchid, op->eventid, op->filesrc);
>             }
>-            if (!qemu_file_monitor_test_expect(
>-                    &data, *op->watchid, op->eventid, op->filesrc))
>+            if (!qemu_file_monitor_test_expect(&data, *op->watchid,
>+                                               op->eventid, op->filesrc,
>+                                               op->swapnext))
>                 goto cleanup;
>             break;
>         case QFILE_MONITOR_TEST_OP_CREATE:
>-- 
>2.21.0

-- 
Wei Yang
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