daemon/ffimodule: simplified pointer to layer capi

previously the pointer for C layer API was stored in Lua, it is stored directly in module data now for fast access. this doesn’t disturb VM when processing requests.

diff --git a/daemon/ffimodule.c b/daemon/ffimodule.c
index 920b125072b603f0c40e687377d9a763c46dfe45..2a4e1129f93a6fb433bc341610ce3d5d3d433a96 100644 (file)
--- a/daemon/ffimodule.c
+++ b/daemon/ffimodule.c
@@ -51,7 +51,7 @@ static void set_metatable(lua_State *L, const char *tname)
 /** @internal Helper for retrieving the right function entrypoint. */
 static inline lua_State *l_ffi_preface(struct kr_module *module, const char *call) {
        lua_State *L = module->lib;
-       lua_rawgeti(L, LUA_REGISTRYINDEX, (intptr_t)module->data);
+       lua_getglobal(L, module->name);
        lua_getfield(L, -1, call);
        lua_remove(L, -2);
        if (lua_isnil(L, -1)) {
@@ -128,10 +128,8 @@ static int l_ffi_deinit(struct kr_module *module)
        if (l_ffi_preface(module, "deinit")) {
                ret = l_ffi_call(L, 1);
        }
-       /* Free the layer API wrapper */
-       lua_rawgeti(L, LUA_REGISTRYINDEX, (intptr_t)module->data);
-       lua_getfield(L, -1, "_layer_capi");
-       knot_layer_api_t* api = lua_touserdata(L, -1);
+       /* Free the layer API wrapper (unconst it) */
+       knot_layer_api_t* api = module->data;
        if (api) {
                LAYER_UNREGISTER(L, api, begin);
                LAYER_UNREGISTER(L, api, finish);
@@ -140,11 +138,6 @@ static int l_ffi_deinit(struct kr_module *module)
                LAYER_UNREGISTER(L, api, reset);
                free(api);
        }
-       lua_pop(L, 2);
-       /* Unref module and unset 'lib', so the module
-        * interface doesn't attempt to close it.
-        */
-       luaL_unref(L, LUA_REGISTRYINDEX, (intptr_t)module->data);
        module->lib = NULL;
        return ret;
 }
@@ -211,59 +204,49 @@ static int l_ffi_layer_produce(knot_layer_t *ctx, knot_pkt_t *pkt)
 }
 #undef LAYER_FFI_CALL
 
-/** Conditionally register layer trampoline */
+/** @internal Conditionally register layer trampoline
+  * @warning Expects 'module.layer' to be on top of Lua stack. */
 #define LAYER_REGISTER(L, api, name) do { \
        int *cb_slot = (int *)((char *)api + sizeof(knot_layer_api_t)); \
-       lua_getfield((L), -1, "layer"); \
        lua_getfield((L), -1, #name); \
        if (!lua_isnil((L), -1)) { \
                (api)->name = l_ffi_layer_ ## name; \
-               cb_slot[SLOT_ ## name] = luaL_ref(L, LUA_REGISTRYINDEX); \
+               cb_slot[SLOT_ ## name] = luaL_ref((L), LUA_REGISTRYINDEX); \
        } else { \
                lua_pop((L), 1); \
        } \
-       lua_pop((L), 1); \
 } while(0)
 
-/** @internal Retrieve C layer api wrapper. */
-static const knot_layer_api_t* l_ffi_layer(struct kr_module *module)
+/** @internal Create C layer api wrapper. */
+static knot_layer_api_t *l_ffi_layer_create(lua_State *L, struct kr_module *module)
 {
-       lua_State *L = module->lib;
-       lua_rawgeti(L, LUA_REGISTRYINDEX, (intptr_t)module->data);
-       lua_getfield(L, -1, "_layer_capi");
-       knot_layer_api_t *api = lua_touserdata(L, -1);
-       lua_pop(L, 1);
-       if (!api) {
-               /* Fabricate layer API wrapping the Lua functions
-                * reserve slots after it for references to Lua callbacks. */
-               const size_t api_length = sizeof(*api) + (SLOT_count * SLOT_size);
-               api = malloc(api_length);
-               if (api) {
-                       memset(api, 0, api_length);
-                       LAYER_REGISTER(L, api, begin);
-                       LAYER_REGISTER(L, api, finish);
-                       LAYER_REGISTER(L, api, consume);
-                       LAYER_REGISTER(L, api, produce);
-                       LAYER_REGISTER(L, api, reset);
-                       /* Begin is always set, as it initializes layer baton. */
-                       api->begin = l_ffi_layer_begin;
-                       api->data = module;
-               }
-               /* Store the api in the registry. */
-               lua_pushlightuserdata(L, api);
-               lua_setfield(L, -2, "_layer_capi");
+       /* Fabricate layer API wrapping the Lua functions
+        * reserve slots after it for references to Lua callbacks. */
+       const size_t api_length = sizeof(knot_layer_api_t) + (SLOT_count * SLOT_size);
+       knot_layer_api_t *api = malloc(api_length);
+       if (api) {
+               memset(api, 0, api_length);
+               LAYER_REGISTER(L, api, begin);
+               LAYER_REGISTER(L, api, finish);
+               LAYER_REGISTER(L, api, consume);
+               LAYER_REGISTER(L, api, produce);
+               LAYER_REGISTER(L, api, reset);
+               /* Begin is always set, as it initializes layer baton. */
+               api->begin = l_ffi_layer_begin;
+               api->data = module;
        }
-       lua_pop(L, 1); /* Clear module table */
        return api;
 }
-#undef LAYER_REGISTER
 
-/** @internal Helper macro for function presence check. */
-#define REGISTER_FFI_CALL(L, attr, name, cb) do { \
-       lua_getfield((L), -1, (name)); \
-       if (!lua_isnil((L), -1)) { attr = cb; } \
-       lua_pop((L), 1); \
-} while (0)
+/** @internal Retrieve C layer api wrapper. */
+static const knot_layer_api_t *l_ffi_layer(struct kr_module *module)
+{
+       if (module) {
+               return (const knot_layer_api_t *)module->data;
+       }
+       return NULL;
+}
+#undef LAYER_REGISTER
 
 int ffimodule_register_lua(struct engine *engine, struct kr_module *module, const char *name)
 {
@@ -284,14 +267,16 @@ int ffimodule_register_lua(struct engine *engine, struct kr_module *module, cons
        module->name = strdup(name);
        module->init = &l_ffi_init;
        module->deinit = &l_ffi_deinit;
-       REGISTER_FFI_CALL(L, module->layer,  "layer",  &l_ffi_layer);
-       module->data = (void *)(intptr_t)luaL_ref(L, LUA_REGISTRYINDEX);
+       /* Bake layer API if defined in module */
+       lua_getfield(L, -1, "layer");
+       if (!lua_isnil(L, -1)) {
+               module->layer = &l_ffi_layer;
+               module->data = l_ffi_layer_create(L, module);
+       }
        module->lib = L;
-       lua_pop(L, 1); /* Clear the module global */
+       lua_pop(L, 2); /* Clear the layer + module global */
        if (module->init) {
                return module->init(module);
        }
        return kr_ok();
 }
-
-#undef REGISTER_FFI_CALL
\ No newline at end of file