Allow persistent option on set_env/4 and unset_env/3

An environment key set with the persistent option will not
be overridden by the ones configured in the application resource
file on load. This means persistent values will stick after the
application is loaded and also on application reload.

2 files changed, 48 insertions, 20 deletions

diff --git a/lib/kernel/src/application.erl b/lib/kernel/src/application.erl
index 4e8ba1b78a..b797d7d362 100644
--- a/lib/kernel/src/application.erl
+++ b/lib/kernel/src/application.erl
@@ -285,16 +285,18 @@ info() ->
 set_env(Application, Key, Val) -> 
     application_controller:set_env(Application, Key, Val).
 
--spec set_env(Application, Par, Val, Timeout) -> 'ok' when
+-spec set_env(Application, Par, Val, Opts) -> 'ok' when
       Application :: atom(),
       Par :: atom(),
       Val :: term(),
-      Timeout :: timeout().
+      Opts :: [{timeout, timeout()} | {persistent, boolean()}].
 
 set_env(Application, Key, Val, infinity) ->
-    application_controller:set_env(Application, Key, Val, infinity);
+    set_env(Application, Key, Val, [{timeout, infinity}]);
 set_env(Application, Key, Val, Timeout) when is_integer(Timeout), Timeout>=0 ->
-    application_controller:set_env(Application, Key, Val, Timeout).
+    set_env(Application, Key, Val, [{timeout, Timeout}]);
+set_env(Application, Key, Val, Opts) when is_list(Opts) ->
+    application_controller:set_env(Application, Key, Val, Opts).
 
 -spec unset_env(Application, Par) -> 'ok' when
       Application :: atom(),
@@ -303,15 +305,17 @@ set_env(Application, Key, Val, Timeout) when is_integer(Timeout), Timeout>=0 ->
 unset_env(Application, Key) -> 
     application_controller:unset_env(Application, Key).
 
--spec unset_env(Application, Par, Timeout) -> 'ok' when
+-spec unset_env(Application, Par, Opts) -> 'ok' when
       Application :: atom(),
       Par :: atom(),
-      Timeout :: timeout().
+      Opts :: [{timeout, timeout()} | {persistent, boolean()}].
 
 unset_env(Application, Key, infinity) ->
-    application_controller:unset_env(Application, Key, infinity);
+    unset_env(Application, Key, [{timeout, infinity}]);
 unset_env(Application, Key, Timeout) when is_integer(Timeout), Timeout>=0 ->
-    application_controller:unset_env(Application, Key, Timeout).
+    unset_env(Application, Key, [{timeout, Timeout}]);
+unset_env(Application, Key, Opts) when is_list(Opts) ->
+    application_controller:unset_env(Application, Key, Opts).
 
 -spec get_env(Par) -> 'undefined' | {'ok', Val} when
       Par :: atom(),
diff --git a/lib/kernel/src/application_controller.erl b/lib/kernel/src/application_controller.erl
index 9ed2c7a7d9..9e3c746f6e 100644
--- a/lib/kernel/src/application_controller.erl
+++ b/lib/kernel/src/application_controller.erl
@@ -461,14 +461,16 @@ permit_application(ApplName, Flag) ->
 
 
 set_env(AppName, Key, Val) ->
-    gen_server:call(?AC, {set_env, AppName, Key, Val}).
-set_env(AppName, Key, Val, Timeout) ->
-    gen_server:call(?AC, {set_env, AppName, Key, Val}, Timeout).
+    gen_server:call(?AC, {set_env, AppName, Key, Val, []}).
+set_env(AppName, Key, Val, Opts) ->
+    Timeout = proplists:get_value(timeout, Opts, 5000),
+    gen_server:call(?AC, {set_env, AppName, Key, Val, Opts}, Timeout).
 
 unset_env(AppName, Key) ->
-    gen_server:call(?AC, {unset_env, AppName, Key}).
-unset_env(AppName, Key, Timeout) ->
-    gen_server:call(?AC, {unset_env, AppName, Key}, Timeout).
+    gen_server:call(?AC, {unset_env, AppName, Key, []}).
+unset_env(AppName, Key, Opts) ->
+    Timeout = proplists:get_value(timeout, Opts, 5000),
+    gen_server:call(?AC, {unset_env, AppName, Key, Opts}, Timeout).
 
 %%%-----------------------------------------------------------------
 %%% call-back functions from gen_server
@@ -609,8 +611,8 @@ check_para([Else | _ParaList], AppName) ->
                | {'change_application_data', _, _}
                | {'permit_application', atom() | {'application',atom(),_},_}
                | {'start_application', _, _}
-               | {'unset_env', _, _}
-               | {'set_env', _, _, _}.
+               | {'unset_env', _, _, _}
+               | {'set_env', _, _, _, _}.
 
 -spec handle_call(calls(), {pid(), term()}, state()) ->
         {'noreply', state()} | {'reply', term(), state()}.
@@ -858,13 +860,25 @@ handle_call(which_applications, _From, S) ->
 	       end, S#state.running),
     {reply, Reply, S};
 
-handle_call({set_env, AppName, Key, Val}, _From, S) ->
+handle_call({set_env, AppName, Key, Val, Opts}, _From, S) ->
     ets:insert(ac_tab, {{env, AppName, Key}, Val}),
-    {reply, ok, S};
+    case proplists:get_value(persistent, Opts, false) of
+	true ->
+	    Fun = fun(Env) -> lists:keystore(Key, 1, Env, {Key, Val}) end,
+	    {reply, ok, S#state{conf_data = change_app_env(S#state.conf_data, AppName, Fun)}};
+	false ->
+	    {reply, ok, S}
+    end;
 
-handle_call({unset_env, AppName, Key}, _From, S) ->
+handle_call({unset_env, AppName, Key, Opts}, _From, S) ->
     ets:delete(ac_tab, {env, AppName, Key}),
-    {reply, ok, S};
+    case proplists:get_value(persistent, Opts, false) of
+	true ->
+	    Fun = fun(Env) -> lists:keydelete(Key, 1, Env) end,
+	    {reply, ok, S#state{conf_data = change_app_env(S#state.conf_data, AppName, Fun)}};
+	false ->
+	    {reply, ok, S}
+    end;
 
 handle_call({control_application, AppName}, {Pid, _Tag}, S) ->
     Control = S#state.control,
@@ -1640,6 +1654,16 @@ merge_env([{App, AppEnv1} | T], Env2, Res) ->
 merge_env([], Env2, Res) ->
     Env2 ++ Res.
 
+%% Changes the environment for the given application
+%% If there is no application, an empty one is created
+change_app_env(Env, App, Fun) ->
+    case get_env_key(App, Env) of
+	{value, AppEnv, RestEnv} ->
+	    [{App, Fun(AppEnv)} | RestEnv];
+	_ ->
+	    [{App, Fun([])} | Env]
+    end.
+
 %% Merges envs for an application.  Env2 overrides Env1
 merge_app_env(Env1, Env2) ->
     merge_app_env(Env1, Env2, []).