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https://github.com/aseprite/aseprite.git
synced 2025-03-17 13:20:45 +00:00
lua: Fix memory leak of dialogs with callbacks pointing to itself
Now we store the callbacks in a table that depends of the lifetime of the dialog (instead of the global registry), so when the dialog is not used anymore/closed, the whole "island" of objects (dialog + callbacks) is GC'd.
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@ -33,6 +33,8 @@
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#include <map>
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#include <string>
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#define TRACE_DIALOG(...) // TRACEARGS
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namespace app {
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namespace script {
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@ -64,10 +66,6 @@ struct Dialog {
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int showRef = LUA_REFNIL;
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lua_State* L = nullptr;
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// A reference to a table with pointers to functions for events
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// (e.g. onclick callbacks).
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int callbacksTableRef = LUA_REFNIL;
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Dialog()
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: window(ui::Window::WithTitleBar, "Script"),
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grid(2, false) {
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@ -75,6 +73,9 @@ struct Dialog {
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window.Close.connect([this](ui::CloseEvent&){ unrefShow(); });
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}
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// When we show the dialog, we reference it from the registry to
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// keep the dialog alive in case that the user declared it as a
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// "local" variable but called Dialog:show{wait=false}
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void refShow(lua_State* L) {
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if (showRef == LUA_REFNIL) {
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this->L = L;
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@ -83,6 +84,11 @@ struct Dialog {
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}
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}
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// When the dialog is closed, we unreference it from the registry so
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// now the dialog can be GC'd if there are no other references to it
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// (all references to the dialog itself from callbacks are stored in
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// the same dialog uservalue, so when the dialog+callbacks are not
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// used anymore they are GC'd as a group)
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void unrefShow() {
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if (showRef != LUA_REFNIL) {
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luaL_unref(this->L, LUA_REGISTRYINDEX, showRef);
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@ -90,6 +96,7 @@ struct Dialog {
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L = nullptr;
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}
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}
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};
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template<typename Signal,
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@ -100,21 +107,31 @@ void Dialog_connect_signal(lua_State* L,
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{
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auto dlg = get_obj<Dialog>(L, 1);
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// Add a reference to the onclick function
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const int ref = dlg->callbacksTableRef;
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lua_rawgeti(L, LUA_REGISTRYINDEX, ref);
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// Here we get the uservalue of the dlg (the table with
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// functions/callbacks) and store a copy of the given function in
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// the stack (index=-1) in that table.
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lua_getuservalue(L, 1);
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lua_len(L, -1);
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const int n = 1+lua_tointegerx(L, -1, nullptr);
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lua_pop(L, 1);
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lua_pushvalue(L, -2); // Copy the function in onclick
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lua_seti(L, -2, n); // Put the copy of the function in the callbacksTableRef
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lua_pop(L, 1); // Pop the length of the table
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lua_pushvalue(L, -2); // Copy the function in stack
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lua_rawseti(L, -2, n); // Put the copy of the function in the uservalue
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lua_pop(L, 1); // Pop the uservalue
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signal.connect(
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base::Bind<void>([=]() {
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callback();
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// In case that the dialog is hidden, we cannot access to the
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// global LUA_REGISTRYINDEX to get its reference.
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if (dlg->showRef == LUA_REFNIL)
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return;
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try {
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lua_rawgeti(L, LUA_REGISTRYINDEX, ref);
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lua_geti(L, -1, n);
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// Get the function "n" from the uservalue table of the dialog
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lua_rawgeti(L, LUA_REGISTRYINDEX, dlg->showRef);
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lua_getuservalue(L, -1);
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lua_rawgeti(L, -1, n);
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if (lua_isfunction(L, -1)) {
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if (lua_pcall(L, 0, 0, 0)) {
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@ -124,9 +141,11 @@ void Dialog_connect_signal(lua_State* L,
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->consolePrint(s);
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}
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}
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else
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lua_pop(L, 1);
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lua_pop(L, 1); // Pop table from the registry
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else {
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ASSERT(false);
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lua_pop(L, 1); // Pop the value which should have been a function
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}
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lua_pop(L, 2); // Pop uservalue & userdata
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}
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catch (const std::exception& ex) {
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// This is used to catch unhandled exception or for
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@ -145,25 +164,23 @@ int Dialog_new(lua_State* L)
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if (lua_isstring(L, 1))
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dlg->window.setText(lua_tostring(L, 1));
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// The uservalue of the dialog userdata will contain a table that
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// stores all the callbacks to handle events. As these callbacks can
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// reference the dialog itself, it's important to store callbacks in
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// this table that depends on the dialog lifetime itself
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// (i.e. uservalue) and in the global registry, because in that case
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// we could create a cyclic reference that would be not GC'd.
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lua_newtable(L);
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#if 0 // Make values in callbacksTableRef table weak. (Weak references
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// are lost for onclick= events with local functions when we use
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// showInBackground() and we left the script scope)
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{
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lua_newtable(L);
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lua_pushstring(L, "v");
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lua_setfield(L, -2, "__mode");
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lua_setmetatable(L, -2);
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}
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#endif
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dlg->callbacksTableRef = luaL_ref(L, LUA_REGISTRYINDEX);
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lua_setuservalue(L, -2);
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TRACE_DIALOG("Dialog_new", dlg);
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return 1;
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}
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int Dialog_gc(lua_State* L)
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{
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auto dlg = get_obj<Dialog>(L, 1);
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luaL_unref(L, LUA_REGISTRYINDEX, dlg->callbacksTableRef);
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TRACE_DIALOG("Dialog_gc", dlg);
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dlg->~Dialog();
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return 0;
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}
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