optimize LuaInstance::get_action_state, LuaInstance::get_hook_state

Lua serialize() is called recursively and concatenates strings.
(in Lua that results in a new string on the stack, with 2 unused old
strings). Collecting garbage every time becomes expensive, so do it
only once at the end. GUI scripts are not memory limited anyway.

diff --git a/gtk2_ardour/luainstance.cc b/gtk2_ardour/luainstance.cc
index b7963737ccc606ef4d6def4b55ec5c5d045579a9..e83bef93eecd8f489ba1ab38b1c740a1caa2280b 100644 (file)
--- a/gtk2_ardour/luainstance.cc
+++ b/gtk2_ardour/luainstance.cc
@@ -977,7 +977,6 @@ LuaInstance::init ()
                        ""
                        "  local function serialize (name, value)"
                        "   local rv = name .. ' = '"
-                       "   collectgarbage()"
                        "   if type(value) == \"number\" or type(value) == \"string\" or type(value) == \"nil\" then"
                        "    return rv .. basic_serialize(value) .. ' '"
                        "   elseif type(value) == \"table\" then"
@@ -985,7 +984,6 @@ LuaInstance::init ()
                        "    for k,v in pairs(value) do"
                        "     local fieldname = string.format(\"%s[%s]\", name, basic_serialize(k))"
                        "     rv = rv .. serialize(fieldname, v) .. ' '"
-                       "     collectgarbage()" // string concatenation allocates a new string
                        "    end"
                        "    return rv;"
                        "   elseif type(value) == \"function\" then"
@@ -1600,7 +1598,15 @@ LuaCallback::get_state (void)
                luabridge::LuaRef savedstate ((*_lua_save)());
                saved = savedstate.cast<std::string>();
        }
-       lua.collect_garbage ();
+
+       lua.collect_garbage (); // this may be expensive:
+       /* Editor::instant_save() calls Editor::get_state() which
+        * calls LuaInstance::get_hook_state() which in turn calls
+        * this LuaCallback::get_state() for every registered hook.
+        *
+        * serialize in _lua_save() allocates many small strings
+        * on the lua-stack, collecting them all may take a ms.
+        */
 
        gchar* b64 = g_base64_encode ((const guchar*)saved.c_str (), saved.size ());
        std::string b64s (b64);
@@ -1676,7 +1682,6 @@ LuaCallback::init (void)
                        ""
                        "  local function serialize (name, value)"
                        "   local rv = name .. ' = '"
-                       "   collectgarbage()"
                        "   if type(value) == \"number\" or type(value) == \"string\" or type(value) == \"nil\" then"
                        "    return rv .. basic_serialize(value) .. ' '"
                        "   elseif type(value) == \"table\" then"
@@ -1684,7 +1689,6 @@ LuaCallback::init (void)
                        "    for k,v in pairs(value) do"
                        "     local fieldname = string.format(\"%s[%s]\", name, basic_serialize(k))"
                        "     rv = rv .. serialize(fieldname, v) .. ' '"
-                       "     collectgarbage()" // string concatenation allocates a new string
                        "    end"
                        "    return rv;"
                        "   elseif type(value) == \"function\" then"