validate: Add a plugin with potential extra checks

And add a way to check that a configured number of instances of a particular
element is used, this is useful to make sure for example that playing a
particular stream doesn't lead to several decoders being instanciated.

validate/plugins/extra_checks/gstvalidateextrachecks.c

@@ -0,0 +1,168 @@
+#include <gst/gst.h>
+#include "../../gst/validate/validate.h"
+#include "../../gst/validate/gst-validate-utils.h"
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#define EXTRA_CHECKS_WRONG_NUMBER_OF_INSTANCES g_quark_from_static_string ("extrachecks::wrong-number-of-instances")
+
+typedef struct
+{
+  gchar *pname;
+  gchar *klass;
+  gint expected_n_instances;
+  gint n_instances;
+} CheckNumInstanceData;
+
+static CheckNumInstanceData *
+gst_validate_check_num_instances_data_new (GstStructure * check)
+{
+  CheckNumInstanceData *data = g_new0 (CheckNumInstanceData, 1);
+
+  if (!gst_structure_get_int (check, "num-instances",
+          &data->expected_n_instances)) {
+    g_error ("[CONFIG ERROR] Mandatory field `num-instances` not found in "
+        "extra-check `num-instances`");
+    goto failed;
+  }
+
+  data->pname = g_strdup (gst_structure_get_string (check, "pipeline-name"));
+  if (!data->pname) {
+    g_error ("[CONFIG ERROR] Mandatory field `pipeline` not found in "
+        "extra-check `num-instances`");
+    goto failed;
+  }
+
+  data->klass = g_strdup (gst_structure_get_string (check, "element-klass"));
+  if (!data->klass) {
+    g_error ("[CONFIG ERROR] Mandatory field `element-klass` not found in "
+        "extra-check `num-instances`");
+    goto failed;
+  }
+
+  return data;
+
+failed:
+  g_free (data);
+  g_free (data->klass);
+
+  return NULL;
+}
+
+static void
+gst_validate_check_num_instances_data_free (CheckNumInstanceData * data)
+{
+  g_free (data->pname);
+  g_free (data);
+}
+
+static void
+gst_validate_check_num_instances (GstValidateOverride * o,
+    GstValidateMonitor * monitor, GstElement * nelem)
+{
+  gchar *pname;
+  CheckNumInstanceData *data = g_object_get_data (G_OBJECT (o), "check-data");
+  GstPipeline *pipe = gst_validate_monitor_get_pipeline (monitor);
+
+  if (!pipe)
+    return;
+
+  pname = gst_object_get_name (GST_OBJECT (pipe));
+  if (g_strcmp0 (data->pname, pname))
+    goto done;
+
+  if (!gst_validate_element_has_klass (nelem, data->klass))
+    return;
+
+  data->n_instances++;
+
+  if (data->n_instances > data->expected_n_instances) {
+    GST_VALIDATE_REPORT (o, EXTRA_CHECKS_WRONG_NUMBER_OF_INSTANCES,
+        "%d instances allows in pipeline %s but already %d where added.",
+        data->expected_n_instances, pname, data->n_instances);
+  }
+  GST_ERROR_OBJECT (nelem, "HERE I AM %d", data->n_instances);
+
+done:
+  g_free (pname);
+  gst_object_unref (pipe);
+}
+
+static void
+runner_stopping (GstValidateRunner * runner, GstValidateOverride * o)
+{
+  CheckNumInstanceData *data = g_object_get_data (G_OBJECT (o), "check-data");
+
+  if (data->expected_n_instances != data->n_instances) {
+    GST_VALIDATE_REPORT (o, EXTRA_CHECKS_WRONG_NUMBER_OF_INSTANCES,
+        "%d instances expected in pipeline %s but %d where added.",
+        data->expected_n_instances, data->pname, data->n_instances);
+  }
+}
+
+static void
+_runner_set (GObject * object, GParamSpec * pspec, gpointer user_data)
+{
+  GstValidateRunner *runner =
+      gst_validate_reporter_get_runner (GST_VALIDATE_REPORTER (object));
+
+  g_signal_connect (runner, "stopping", G_CALLBACK (runner_stopping), object);
+  gst_object_unref (runner);
+}
+
+static void
+gst_validate_add_num_instances_check (GstStructure * structure)
+{
+  CheckNumInstanceData *data =
+      gst_validate_check_num_instances_data_new (structure);
+  GstValidateOverride *o = gst_validate_override_new ();
+
+  g_object_set_data_full (G_OBJECT (o), "check-data", data,
+      (GDestroyNotify) gst_validate_check_num_instances_data_free);
+
+  gst_validate_override_set_element_added_handler (o,
+      gst_validate_check_num_instances);
+
+  g_signal_connect (o, "notify::validate-runner", G_CALLBACK (_runner_set),
+      NULL);
+
+  gst_validate_override_register_by_type (GST_TYPE_BIN, o);
+  gst_object_unref (o);
+}
+
+static gboolean
+gst_validate_extra_checks_init (GstPlugin * plugin)
+{
+  GList *config, *tmp;
+  config = gst_validate_plugin_get_config (plugin);
+
+  if (!config)
+    return TRUE;
+
+  for (tmp = config; tmp; tmp = tmp->next) {
+    GstStructure *check = tmp->data;
+
+    if (gst_structure_has_field (check, "num-instances"))
+      gst_validate_add_num_instances_check (check);
+  }
+
+  gst_validate_issue_register (gst_validate_issue_new
+      (EXTRA_CHECKS_WRONG_NUMBER_OF_INSTANCES,
+          "The configured number of possible instances of an element type"
+          " in a pipeline is not respected.",
+          "The `num-instances` extra checks allow user to make sure that"
+          " a previously defined number of instances of an element is added"
+          " in a given pipeline, that test failed.",
+          GST_VALIDATE_REPORT_LEVEL_CRITICAL));
+
+  return TRUE;
+}
+
+GST_PLUGIN_DEFINE (GST_VERSION_MAJOR,
+    GST_VERSION_MINOR,
+    extrachecks,
+    "GstValidate plugin that implements extra, configurable tests.",
+    gst_validate_extra_checks_init, VERSION, "LGPL", GST_PACKAGE_NAME,
+    GST_PACKAGE_ORIGIN)

validate/plugins/extra_checks/meson.build

@@ -0,0 +1,10 @@
+shared_library('gstextrachecks',
+               'gstvalidateextrachecks.c',
+                include_directories : inc_dirs,
+                c_args: ['-DHAVE_CONFIG_H'],
+                install: true,
+                install_dir: validate_plugins_install_dir,
+                dependencies : [gst_dep, gst_pbutils_dep],
+                link_with : [gstvalidate]
+               )
+

validate/plugins/meson.build

@@ -1,6 +1,7 @@
 subdir('fault_injection')
 subdir('gapplication')
 subdir('ssim')
+subdir('extra_checks')
 
 if gtk_dep.found()
     subdir('gtk')