tests/qtest/qos-test: dump qos graph if verbose

If qtests were run in verbose mode (i.e. if --verbose CL argument was
provided) then dump the generated qos graph (all nodes and edges,
along with their current individual availability status) to stdout,
which allows to identify problems in the created qos graph e.g. when
writing new qos tests.

See API doc comment on function qos_dump_graph() for details.

Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
Message-Id: <6bffb6e38589fb2c06a2c1b5deed33f3e710fed1.1611704181.git.qemu_oss@crudebyte.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

tests/qtest/libqos/qgraph.c

@@ -805,3 +805,48 @@ void qos_delete_cmd_line(const char *name)
         node->command_line = NULL;
     }
 }
+
+void qos_dump_graph(void)
+{
+    GList *keys;
+    GList *l;
+    QOSGraphEdgeList *list;
+    QOSGraphEdge *e, *next;
+    QOSGraphNode *dest_node, *node;
+
+    qos_printf("ALL QGRAPH EDGES: {\n");
+    keys = g_hash_table_get_keys(edge_table);
+    for (l = keys; l != NULL; l = l->next) {
+        const gchar *key = l->data;
+        qos_printf("\t src='%s'\n", key);
+        list = get_edgelist(key);
+        QSLIST_FOREACH_SAFE(e, list, edge_list, next) {
+            dest_node = g_hash_table_lookup(node_table, e->dest);
+            qos_printf("\t\t|-> dest='%s' type=%d (node=%p)",
+                       e->dest, e->type, dest_node);
+            if (!dest_node) {
+                qos_printf_literal(" <------- ERROR !");
+            }
+            qos_printf_literal("\n");
+        }
+    }
+    g_list_free(keys);
+    qos_printf("}\n");
+
+    qos_printf("ALL QGRAPH NODES: {\n");
+    keys = g_hash_table_get_keys(node_table);
+    for (l = keys; l != NULL; l = l->next) {
+        const gchar *key = l->data;
+        node = g_hash_table_lookup(node_table, key);
+        qos_printf("\t name='%s' ", key);
+        if (node->qemu_name) {
+            qos_printf_literal("qemu_name='%s' ", node->qemu_name);
+        }
+        qos_printf_literal("type=%d cmd_line='%s' [%s]\n",
+                           node->type, node->command_line,
+                           node->available ? "available" : "UNAVAILBLE"
+        );
+    }
+    g_list_free(keys);
+    qos_printf("}\n");
+}

tests/qtest/libqos/qgraph.h

@@ -586,5 +586,25 @@ QOSGraphObject *qos_machine_new(QOSGraphNode *node, QTestState *qts);
 QOSGraphObject *qos_driver_new(QOSGraphNode *node, QOSGraphObject *parent,
                                QGuestAllocator *alloc, void *arg);
 
+/**
+ * Just for debugging purpose: prints all currently existing nodes and
+ * edges to stdout.
+ *
+ * All qtests add themselves to the overall qos graph by calling qgraph
+ * functions that add device nodes and edges between the individual graph
+ * nodes for tests. As the actual graph is assmbled at runtime by the qos
+ * subsystem, it is sometimes not obvious how the overall graph looks like.
+ * E.g. when writing new tests it may happen that those new tests are simply
+ * ignored by the qtest framework.
+ *
+ * This function allows to identify problems in the created qgraph. Keep in
+ * mind: only tests with a path down from the actual test case node (leaf) up
+ * to the graph's root node are actually executed by the qtest framework. And
+ * the qtest framework uses QMP to automatically check which QEMU drivers are
+ * actually currently available, and accordingly qos marks certain pathes as
+ * 'unavailable' in such cases (e.g. when QEMU was compiled without support for
+ * a certain feature).
+ */
+void qos_dump_graph(void);
 
 #endif

tests/qtest/qos-test.c

@@ -322,6 +322,9 @@ int main(int argc, char **argv)
     qos_set_machines_devices_available();
 
     qos_graph_foreach_test_path(walk_path);
+    if (g_test_verbose()) {
+        qos_dump_graph();
+    }
     g_test_run();
     qtest_end();
     qos_graph_destroy();