Add custom deleter for plugin admissioner

Author: AlexSutila

src/export_admissioner.cpp

@@ -30,18 +30,33 @@ pypluginAdmissioner_params {
 static bool pypluginAdmissioner_admit(admissioner_t *, const request_t *);
 static admissioner_t *pypluginAdmissioner_clone(admissioner_t *);
 static void pypluginAdmissioner_free(admissioner_t *);
-static void pypluginAdmissioner_update(admissioner_t *, const request_t *, const uint64_t);
+static void pypluginAdmissioner_update(admissioner_t *, const request_t *,
+                                       const uint64_t);
+
+struct PypluginAdmissionerParamsDeleter {
+  void operator()(pypluginAdmissioner_params_t *ptr) const {
+    if (ptr != nullptr) {
+      if (!ptr->admissioner_free_hook.is_none()) {
+        try {
+          ptr->admissioner_free_hook(ptr->data);
+        } catch (...) { }
+      }
+      delete ptr;
+    }
+  }
+};
 
-// TODO: Free hook is currently not invoked at all, see export_cache.cpp and follow
-// their implementation pattern of using a custom deleter alongside std::unique_ptr
 admissioner_t *create_plugin_admissioner(std::string admissioner_name,
-                                        py::function admissioner_init_hook,
-                                        py::function admissioner_admit_hook,
-                                        py::function admissioner_clone_hook,
-                                        py::function admissioner_update_hook,
-                                        py::function admissioner_free_hook) {
+                                         py::function admissioner_init_hook,
+                                         py::function admissioner_admit_hook,
+                                         py::function admissioner_clone_hook,
+                                         py::function admissioner_update_hook,
+                                         py::function admissioner_free_hook) {
+  std::unique_ptr<pypluginAdmissioner_params_t,
+                  PypluginAdmissionerParamsDeleter>
+      params;
   admissioner_t *admissioner = nullptr;
-  try{
+  try {
     admissioner = (admissioner_t *)malloc(sizeof(admissioner_t));
     if (!admissioner) {
       throw std::runtime_error("Failed to initialize admissioner structure");
@@ -55,9 +70,9 @@ admissioner_t *create_plugin_admissioner(std::string admissioner_name,
     admissioner->update = pypluginAdmissioner_update;
 
     // Initialize pointers to python hook functions
-    std::unique_ptr<pypluginAdmissioner_params_t> params =
-        std::make_unique<pypluginAdmissioner_params_t>(
-            pypluginAdmissioner_params_t());
+    params = std::unique_ptr<pypluginAdmissioner_params_t,
+                             PypluginAdmissionerParamsDeleter>(
+        new pypluginAdmissioner_params_t(), PypluginAdmissionerParamsDeleter());
     params->data = admissioner_init_hook();
     params->admissioner_admit_hook = admissioner_admit_hook;
     params->admissioner_clone_hook = admissioner_clone_hook;
@@ -68,37 +83,36 @@ admissioner_t *create_plugin_admissioner(std::string admissioner_name,
     // Transfer ownership of params to admissioner
     admissioner->params = params.release();
     return admissioner;
-
   } catch (...) {
-    if (admissioner)
-      free(admissioner);
+    if (admissioner) free(admissioner);
     throw;
   }
 }
 
-static bool pypluginAdmissioner_admit(admissioner_t *admissioner, const request_t *req) {
-  pypluginAdmissioner_params_t* params =
-      (pypluginAdmissioner_params_t*)admissioner->params;
+static bool pypluginAdmissioner_admit(admissioner_t *admissioner,
+                                      const request_t *req) {
+  pypluginAdmissioner_params_t *params =
+      (pypluginAdmissioner_params_t *)admissioner->params;
   return params->admissioner_admit_hook(params->data, req).cast<bool>();
 }
 
 static admissioner_t *pypluginAdmissioner_clone(admissioner_t *admissioner) {
-  pypluginAdmissioner_params_t* params =
-      (pypluginAdmissioner_params_t*)admissioner->params;
+  pypluginAdmissioner_params_t *params =
+      (pypluginAdmissioner_params_t *)admissioner->params;
   return params->admissioner_clone_hook(params->data).cast<admissioner_t *>();
 }
 
 static void pypluginAdmissioner_free(admissioner_t *admissioner) {
-  pypluginAdmissioner_params_t* params =
-      (pypluginAdmissioner_params_t*)admissioner->params;
+  pypluginAdmissioner_params_t *params =
+      (pypluginAdmissioner_params_t *)admissioner->params;
   params->admissioner_free_hook(params->data);
 }
 
 static void pypluginAdmissioner_update(admissioner_t *admissioner,
                                        const request_t *req,
                                        const uint64_t cache_size) {
-  pypluginAdmissioner_params_t* params =
-      (pypluginAdmissioner_params_t*)admissioner->params;
+  pypluginAdmissioner_params_t *params =
+      (pypluginAdmissioner_params_t *)admissioner->params;
   params->admissioner_update_hook(params->data, req, cache_size);
 }
 
@@ -204,18 +218,10 @@ void export_admissioner(py::module &m) {
       m, "create_size_probabilistic_admissioner");
   export_admissioner_creator<create_adaptsize_admissioner>(
       m, "create_adaptsize_admissioner");
-
-  m.def(
-    "create_plugin_admissioner",
-    &create_plugin_admissioner,
-    "admissioner_name",
-    "admissioner_init_hook",
-    "admissioner_admit_hook",
-    "admissioner_clone_hook",
-    "admissioner_update_hook",
-    "admissioner_free_hook",
-    py::return_value_policy::take_ownership
-  );
+  m.def("create_plugin_admissioner", &create_plugin_admissioner,
+        "admissioner_name", "admissioner_init_hook", "admissioner_admit_hook",
+        "admissioner_clone_hook", "admissioner_update_hook",
+        "admissioner_free_hook", py::return_value_policy::take_ownership);
 }
 
 }  // namespace libcachesim