From fcbc24440945a13b379b2b6135599c982bf8bdf0 Mon Sep 17 00:00:00 2001
From: Dan Gudmundsson <dgud@erlang.org>
Date: Tue, 7 Jul 2015 10:38:38 +0200
Subject: wx: Add event callback fastpath

Avoids spawn but can deadlock
---
 lib/wx/api_gen/wx_extra/wxEvtHandler.erl |  2 ++
 lib/wx/src/gen/wxEvtHandler.erl          |  2 ++
 lib/wx/src/wxe_server.erl                | 35 ++++++++++++++++++--------------
 lib/wx/test/wx_event_SUITE.erl           | 11 +++++++---
 4 files changed, 32 insertions(+), 18 deletions(-)

(limited to 'lib/wx')

diff --git a/lib/wx/api_gen/wx_extra/wxEvtHandler.erl b/lib/wx/api_gen/wx_extra/wxEvtHandler.erl
index c9726fd475..85ebc093f5 100644
--- a/lib/wx/api_gen/wx_extra/wxEvtHandler.erl
+++ b/lib/wx/api_gen/wx_extra/wxEvtHandler.erl
@@ -70,6 +70,8 @@ connect(This=#wx_ref{type=ThisT}, EventType, Options) ->
 parse_opts([{callback,Fun}|R], Opts) when is_function(Fun) ->
     %% Check Fun Arity?
     parse_opts(R, Opts#evh{cb=Fun});
+parse_opts([{callback,CB={nospawn, Fun}}|R], Opts) when is_function(Fun) ->
+    parse_opts(R, Opts#evh{cb=CB});
 parse_opts([callback|R], Opts) ->
     parse_opts(R, Opts#evh{cb=self()});
 parse_opts([{userData, UserData}|R],Opts) ->
diff --git a/lib/wx/src/gen/wxEvtHandler.erl b/lib/wx/src/gen/wxEvtHandler.erl
index 6e9770bbb6..2d0a87f4dd 100644
--- a/lib/wx/src/gen/wxEvtHandler.erl
+++ b/lib/wx/src/gen/wxEvtHandler.erl
@@ -90,6 +90,8 @@ connect(This=#wx_ref{type=ThisT}, EventType, Options) ->
 parse_opts([{callback,Fun}|R], Opts) when is_function(Fun) ->
     %% Check Fun Arity?
     parse_opts(R, Opts#evh{cb=Fun});
+parse_opts([{callback,CB={nospawn, Fun}}|R], Opts) when is_function(Fun) ->
+    parse_opts(R, Opts#evh{cb=CB});
 parse_opts([callback|R], Opts) ->
     parse_opts(R, Opts#evh{cb=self()});
 parse_opts([{userData, UserData}|R],Opts) ->
diff --git a/lib/wx/src/wxe_server.erl b/lib/wx/src/wxe_server.erl
index 6679fcfbe1..cc253b1143 100644
--- a/lib/wx/src/wxe_server.erl
+++ b/lib/wx/src/wxe_server.erl
@@ -240,6 +240,8 @@ handle_connect(Object, EvData=#evh{handler=Handler},
 invoke_cb({{Ev=#wx{}, Ref=#wx_ref{}}, FunId,_}, _S) ->
     %% Event callbacks
     case get(FunId) of
+	{{nospawn, Fun}, _} when is_function(Fun) ->
+	    invoke_callback_fun(fun() -> Fun(Ev, Ref), <<>> end);
 	{Fun,_} when is_function(Fun) ->
 	    invoke_callback(fun() -> Fun(Ev, Ref), <<>> end);
 	{Pid,_} when is_pid(Pid) -> %% wx_object sync event
@@ -258,21 +260,10 @@ invoke_cb({FunId, Args, _}, _S) when is_list(Args), is_integer(FunId) ->
 
 invoke_callback(Fun) ->
     Env = get(?WXE_IDENTIFIER),
-    CB = fun() ->
-		 wx:set_env(Env),
-		 wxe_util:cast(?WXE_CB_START, <<>>),
-		 Res = try
-			   Return = Fun(),
-			   true = is_binary(Return),
-			   Return
-		       catch _:Reason ->
-			       ?log("Callback fun crashed with {'EXIT, ~p, ~p}~n",
-				    [Reason, erlang:get_stacktrace()]),
-			       <<>>
-		       end,
-		 wxe_util:cast(?WXE_CB_RETURN, Res)
-	 end,
-    spawn(CB),
+    spawn(fun() ->
+		  wx:set_env(Env),
+		  invoke_callback_fun(Fun)
+	  end),
     ok.
 
 invoke_callback(Pid, Ev, Ref) ->
@@ -302,6 +293,20 @@ invoke_callback(Pid, Ev, Ref) ->
     spawn(CB),
     ok.
 
+invoke_callback_fun(Fun) ->
+    wxe_util:cast(?WXE_CB_START, <<>>),
+    Res = try
+	      Return = Fun(),
+	      true = is_binary(Return),
+	      Return
+	  catch _:Reason ->
+		  ?log("Callback fun crashed with {'EXIT, ~p, ~p}~n",
+		       [Reason, erlang:get_stacktrace()]),
+		  <<>>
+	  end,
+    wxe_util:cast(?WXE_CB_RETURN, Res).
+
+
 get_wx_object_state(Pid) ->
     case process_info(Pid, dictionary) of
 	{dictionary, Dict} ->
diff --git a/lib/wx/test/wx_event_SUITE.erl b/lib/wx/test/wx_event_SUITE.erl
index 2d6f7b6aaa..7e71d6ca69 100644
--- a/lib/wx/test/wx_event_SUITE.erl
+++ b/lib/wx/test/wx_event_SUITE.erl
@@ -78,7 +78,6 @@ connect(Config) ->
 		 Tester ! {got_size, UserD}
 	 end,
     
-    ?m(ok, wxFrame:connect(Frame,  size)),
     ?m(ok, wxEvtHandler:connect(Panel, size,[{skip, true},{userData, panel}])),
     ?m(ok, wxEvtHandler:connect(Panel, size,[{callback,CB},{userData, panel}])),
 
@@ -91,12 +90,16 @@ connect(Config) ->
     ?m(ok, wxWindow:connect(Window, size,[{callback,CB},{userData, window}])),
     ?m(ok, wxWindow:connect(Window, size,[{skip,true},{userData, window}])),
 
+    %% For trivial side effect free callbacks, can deadlock easily otherwise
+    CB1 = fun(_,_) -> Tester ! {got_size, nospawn_cb} end,
+    ?m(ok, wxWindow:connect(Frame,  size, [{callback,{nospawn, CB1}}])),
+    ?m(ok, wxFrame:connect(Frame,  size, [{skip, true}])),
     ?m(true, wxFrame:show(Frame)),
 
     wxWindow:setSize(Panel, {200,100}),
     wxWindow:setSize(Window, {200,100}),
 
-    get_size_messages(Frame, [frame, panel_cb, window_cb, window]),
+    get_size_messages(Frame, [frame, panel_cb, window_cb, window, nospawn_cb]),
     
     wx_test_lib:wx_destroy(Frame, Config).
 
@@ -115,7 +118,9 @@ get_size_messages(Frame, Msgs) ->
 	    ?m(false, lists:member(window, Msgs)),
 	    get_size_messages(Frame, lists:delete(window_cb, Msgs));
 	{got_size,panel} -> 
-	    get_size_messages(Frame, lists:delete(panel_cb, Msgs));	
+	    get_size_messages(Frame, lists:delete(panel_cb, Msgs));
+	{got_size,nospawn_cb} ->
+	    get_size_messages(Frame, lists:delete(nospawn_cb, Msgs));
 	Other ->
 	    ?error("Got unexpected msg ~p ~p~n", [Other,Msgs])
     after 1000 ->
-- 
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