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authorBjörn Gustavsson <[email protected]>2016-05-03 06:51:25 +0200
committerBjörn Gustavsson <[email protected]>2016-05-04 10:21:30 +0200
commit7a1ff887383674e786a7c22aceefb0365ed91818 (patch)
tree4135603ed3372a6eb464f6ff20e05bfac5730130 /lib/kernel/src
parentf8e4ac533d388b39d5980092e5dd7a9d4ffee60b (diff)
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Correctly handle multiple load attempts when on_load is pending
If an on_load function had not yet returned, the code server would only correctly handle calls to code:ensure_loaded/1. That is, each process that called code:ensured_loaded/1 for the module in question would be suspended until the on_load function had returned. The code server handled calls to code:load_binary/1, code:load_file/1, and code:load_abs/1 in the same way as for code:ensure_loaded/1. That means that if call to one those functions attempted to load *different* code for the module, that code would not get loaded. Note that code:finish_loading/1 (code:atomic_load/1) will still return {error,pending_on_load} if there is a pending on_load function for one of the modules that are about to be loaded. The reason is that code:finish_loading/1 is meant to either succeed directly, or fail quickly if there is any problem.
Diffstat (limited to 'lib/kernel/src')
-rw-r--r--lib/kernel/src/code_server.erl131
1 files changed, 77 insertions, 54 deletions
diff --git a/lib/kernel/src/code_server.erl b/lib/kernel/src/code_server.erl
index 10264382eb..6174136507 100644
--- a/lib/kernel/src/code_server.erl
+++ b/lib/kernel/src/code_server.erl
@@ -32,8 +32,12 @@
-import(lists, [foreach/2]).
+-type on_load_action() ::
+ fun((term(), state()) -> {'reply',term(),state()} |
+ {'noreply',state()}).
+
-type on_load_item() :: {{pid(),reference()},module(),
- file:name_all(),[pid()]}.
+ [{pid(),on_load_action()}]}.
-record(state, {supervisor :: pid(),
root :: file:name_all(),
@@ -304,7 +308,7 @@ handle_call({ensure_loaded,Mod}, From, St) when is_atom(Mod) ->
true ->
{reply,{module,Mod},St};
false when St#state.mode =:= interactive ->
- load_file(Mod, From, St);
+ ensure_loaded(Mod, From, St);
false ->
{reply,{error,embedded},St}
end;
@@ -1084,13 +1088,11 @@ load_abs(File, Mod, From, St) ->
{reply,{error,nofile},St}
end.
-try_load_module(File, Mod, Bin, From, St0) ->
- case pending_on_load(Mod, From, St0) of
- no ->
- try_load_module_1(File, Mod, Bin, From, St0);
- {yes,St} ->
- {noreply,St}
- end.
+try_load_module(File, Mod, Bin, From, St) ->
+ Action = fun(_, S) ->
+ try_load_module_1(File, Mod, Bin, From, S)
+ end,
+ handle_pending_on_load(Action, Mod, From, St).
try_load_module_1(File, Mod, Bin, From, #state{moddb=Db}=St) ->
case is_sticky(Mod, Db) of
@@ -1117,19 +1119,19 @@ try_load_module_2(File, Mod, Bin, From, Architecture,
{reply,ok,St}
end.
-try_load_module_3(File, Mod, Bin, From, Architecture,
- #state{moddb=Db}=St) ->
- case erlang:load_module(Mod, Bin) of
- {module,Mod} = Module ->
- ets:insert(Db, {Mod,File}),
- post_beam_load([Mod], Architecture, St),
- {reply,Module,St};
- {error,on_load} ->
- handle_on_load(Mod, File, From, St);
- {error,What} = Error ->
- error_msg("Loading of ~ts failed: ~p\n", [File, What]),
- {reply,Error,St}
- end.
+try_load_module_3(File, Mod, Bin, From, Architecture, St0) ->
+ Action = fun({module,_}=Module, #state{moddb=Db}=S) ->
+ ets:insert(Db, {Mod,File}),
+ post_beam_load([Mod], Architecture, S),
+ {reply,Module,S};
+ ({error,on_load_failure}=Error, S) ->
+ {reply,Error,S};
+ ({error,What}=Error, S) ->
+ error_msg("Loading of ~ts failed: ~p\n", [File, What]),
+ {reply,Error,S}
+ end,
+ Res = erlang:load_module(Mod, Bin),
+ handle_on_load(Res, Action, Mod, From, St0).
hipe_result_to_status(Result, #state{moddb=Db}) ->
case Result of
@@ -1154,11 +1156,22 @@ int_list([H|T]) when is_integer(H) -> int_list(T);
int_list([_|_]) -> false;
int_list([]) -> true.
+ensure_loaded(Mod, From, St0) ->
+ Action = fun(_, S) ->
+ case erlang:module_loaded(Mod) of
+ true ->
+ {reply,{module,Mod},S};
+ false ->
+ load_file_1(Mod, From, S)
+ end
+ end,
+ handle_pending_on_load(Action, Mod, From, St0).
+
load_file(Mod, From, St0) ->
- case pending_on_load(Mod, From, St0) of
- no -> load_file_1(Mod, From, St0);
- {yes,St} -> {noreply,St}
- end.
+ Action = fun(_, S) ->
+ load_file_1(Mod, From, S)
+ end,
+ handle_pending_on_load(Action, Mod, From, St0).
load_file_1(Mod, From, #state{path=Path}=St) ->
case mod_to_bin(Path, Mod) of
@@ -1308,55 +1321,56 @@ run([F|Fs], Data0) ->
%% The on_load functionality.
%% -------------------------------------------------------
-handle_on_load(Mod, File, From, #state{on_load=OnLoad0}=St0) ->
+handle_on_load({error,on_load}, Action, Mod, From, St0) ->
+ #state{on_load=OnLoad0} = St0,
Fun = fun() ->
Res = erlang:call_on_load_function(Mod),
exit(Res)
end,
PidRef = spawn_monitor(Fun),
- OnLoad = [{PidRef,Mod,File,[From]}|OnLoad0],
+ PidAction = {From,Action},
+ OnLoad = [{PidRef,Mod,[PidAction]}|OnLoad0],
St = St0#state{on_load=OnLoad},
- {noreply,St}.
+ {noreply,St};
+handle_on_load(Res, Action, _, _, St) ->
+ Action(Res, St).
-pending_on_load(_, _, #state{on_load=[]}) ->
- no;
-pending_on_load(Mod, From, #state{on_load=OnLoad0}=St) ->
+handle_pending_on_load(Action, Mod, From, #state{on_load=OnLoad0}=St) ->
case lists:keyfind(Mod, 2, OnLoad0) of
false ->
- no;
- {{From,_Ref},Mod,_File,_Pids} ->
+ Action(ok, St);
+ {{From,_Ref},Mod,_Pids} ->
%% The on_load function tried to make an external
%% call to its own module. That would be a deadlock.
%% Fail the call. (The call is probably from error_handler,
%% and it will ignore the actual error reason and cause
%% an undef execption.)
- _ = reply(From, {error,deadlock}),
- {yes,St};
- {_,_,_,_} ->
- OnLoad = pending_on_load_1(Mod, From, OnLoad0),
- {yes,St#state{on_load=OnLoad}}
+ {reply,{error,deadlock},St};
+ {_,_,_} ->
+ OnLoad = handle_pending_on_load_1(Mod, {From,Action}, OnLoad0),
+ {noreply,St#state{on_load=OnLoad}}
end.
-pending_on_load_1(Mod, From, [{PidRef,Mod,File,Pids}|T]) ->
- [{PidRef,Mod,File,[From|Pids]}|T];
-pending_on_load_1(Mod, From, [H|T]) ->
- [H|pending_on_load_1(Mod, From, T)];
-pending_on_load_1(_, _, []) -> [].
+handle_pending_on_load_1(Mod, From, [{PidRef,Mod,Pids}|T]) ->
+ [{PidRef,Mod,[From|Pids]}|T];
+handle_pending_on_load_1(Mod, From, [H|T]) ->
+ [H|handle_pending_on_load_1(Mod, From, T)];
+handle_pending_on_load_1(_, _, []) -> [].
-finish_on_load(PidRef, OnLoadRes, #state{on_load=OnLoad0,moddb=Db}=State) ->
+finish_on_load(PidRef, OnLoadRes, #state{on_load=OnLoad0}=St0) ->
case lists:keyfind(PidRef, 1, OnLoad0) of
false ->
%% Since this process in general silently ignores messages
%% it doesn't understand, it should also ignore a 'DOWN'
%% message with an unknown reference.
- State;
- {PidRef,Mod,File,WaitingPids} ->
- finish_on_load_1(Mod, File, OnLoadRes, WaitingPids, Db),
- OnLoad = [E || {R,_,_,_}=E <- OnLoad0, R =/= PidRef],
- State#state{on_load=OnLoad}
+ St0;
+ {PidRef,Mod,Waiting} ->
+ St = finish_on_load_1(Mod, OnLoadRes, Waiting, St0),
+ OnLoad = [E || {R,_,_}=E <- OnLoad0, R =/= PidRef],
+ St#state{on_load=OnLoad}
end.
-finish_on_load_1(Mod, File, OnLoadRes, WaitingPids, Db) ->
+finish_on_load_1(Mod, OnLoadRes, Waiting, St) ->
Keep = OnLoadRes =:= ok,
erlang:finish_after_on_load(Mod, Keep),
Res = case Keep of
@@ -1365,11 +1379,20 @@ finish_on_load_1(Mod, File, OnLoadRes, WaitingPids, Db) ->
_ = erts_code_purger:purge(Mod),
{error,on_load_failure};
true ->
- ets:insert(Db, {Mod,File}),
{module,Mod}
end,
- _ = [reply(Pid, Res) || Pid <- WaitingPids],
- ok.
+ finish_on_load_2(Waiting, Res, St).
+
+finish_on_load_2([{Pid,Action}|T], Res, St0) ->
+ case Action(Res, St0) of
+ {reply,Rep,St} ->
+ _ = reply(Pid, Rep),
+ finish_on_load_2(T, Res, St);
+ {noreply,St} ->
+ finish_on_load_2(T, Res, St)
+ end;
+finish_on_load_2([], _, St) ->
+ St.
finish_on_load_report(_Mod, Atom) when is_atom(Atom) ->
%% No error reports for atoms.