File 2347-stdlib-Make-gen_event-callbacks-optional.patch of Package erlang
From db632b91f41c4a01be68d821d6942ff32b86e40b Mon Sep 17 00:00:00 2001
From: Zandra Norman <zandra@erlang.org>
Date: Mon, 23 Jan 2017 16:07:52 +0100
Subject: [PATCH 2/4] stdlib: Make gen_event callbacks optional
---
lib/stdlib/doc/src/gen_event.xml | 18 +++
lib/stdlib/src/gen_event.erl | 19 +++-
lib/stdlib/test/dummy_h.erl | 6 +-
lib/stdlib/test/erl_internal_SUITE.erl | 2 +-
lib/stdlib/test/gen_event_SUITE.erl | 132 +++++++++++++++++++++-
lib/stdlib/test/gen_event_SUITE_data/oc_event.erl | 40 +++++++
6 files changed, 207 insertions(+), 10 deletions(-)
create mode 100644 lib/stdlib/test/gen_event_SUITE_data/oc_event.erl
diff --git a/lib/stdlib/doc/src/gen_event.xml b/lib/stdlib/doc/src/gen_event.xml
index 42e952fd4..56cb7974a 100644
--- a/lib/stdlib/doc/src/gen_event.xml
+++ b/lib/stdlib/doc/src/gen_event.xml
@@ -579,6 +579,13 @@ gen_event:stop -----> Module:terminate/2
<v>Extra = term()</v>
</type>
<desc>
+ <note>
+ <p>This callback is optional, so callback modules need not export it.
+ If a release upgrade/downgrade with <c>Change={advanced,Extra}</c>
+ specified in the <c>.appup</c> file is made when <c>code_change/3</c>
+ isn't implemented the event handler will crash with an <c>undef</c> error
+ reason.</p>
+ </note>
<p>This function is called for an installed event handler that
is to update its internal state during a release
upgrade/downgrade, that is, when the instruction
@@ -759,6 +766,12 @@ gen_event:stop -----> Module:terminate/2
<v> Id = term()</v>
</type>
<desc>
+ <note>
+ <p>This callback is optional, so callback modules need not
+ export it. The <c>gen_event</c> module provides a default
+ implementation of this function that logs about the unexpected
+ <c>Info</c> message, drops it and returns <c>{noreply, State}</c>.</p>
+ </note>
<p>This function is called for each installed event handler when
an event manager receives any other message than an event or
a synchronous request (or a system message).</p>
@@ -815,6 +828,11 @@ gen_event:stop -----> Module:terminate/2
<v> Args = Reason = Term = term()</v>
</type>
<desc>
+ <note>
+ <p>This callback is optional, so callback modules need not
+ export it. The <c>gen_event</c> module provides a default
+ implementation without cleanup.</p>
+ </note>
<p>Whenever an event handler is deleted from an event manager,
this function is called. It is to be the opposite of
<seealso marker="#Module:init/1"><c>Module:init/1</c></seealso>
diff --git a/lib/stdlib/src/gen_event.erl b/lib/stdlib/src/gen_event.erl
index 0aebf1bdc..0c50b2aa0 100644
--- a/lib/stdlib/src/gen_event.erl
+++ b/lib/stdlib/src/gen_event.erl
@@ -109,7 +109,8 @@
State :: term(),
Status :: term().
--optional_callbacks([format_status/2]).
+-optional_callbacks(
+ [handle_info/2, terminate/2, code_change/3, format_status/2]).
%%---------------------------------------------------------------------------
@@ -577,6 +578,10 @@ server_update(Handler1, Func, Event, SName) ->
do_terminate(Mod1, Handler1, remove_handler, State,
remove, SName, normal),
no;
+ {'EXIT', {undef, [{Mod1, handle_info, [_,_], _}|_]}} ->
+ error_logger:warning_msg("** Undefined handle_info in ~p~n"
+ "** Unhandled message: ~p~n", [Mod1, Event]),
+ {ok, Handler1};
Other ->
do_terminate(Mod1, Handler1, {error, Other}, State,
Event, SName, crash),
@@ -698,9 +703,15 @@ server_call_update(Handler1, Query, SName) ->
end.
do_terminate(Mod, Handler, Args, State, LastIn, SName, Reason) ->
- Res = (catch Mod:terminate(Args, State)),
- report_terminate(Handler, Reason, Args, State, LastIn, SName, Res),
- Res.
+ case erlang:function_exported(Mod, terminate, 2) of
+ true ->
+ Res = (catch Mod:terminate(Args, State)),
+ report_terminate(Handler, Reason, Args, State, LastIn, SName, Res),
+ Res;
+ false ->
+ report_terminate(Handler, Reason, Args, State, LastIn, SName, ok),
+ ok
+ end.
report_terminate(Handler, crash, {error, Why}, State, LastIn, SName, _) ->
report_terminate(Handler, Why, State, LastIn, SName);
diff --git a/lib/stdlib/test/dummy_h.erl b/lib/stdlib/test/dummy_h.erl
index bc89cb4fd..70c0eafbd 100644
--- a/lib/stdlib/test/dummy_h.erl
+++ b/lib/stdlib/test/dummy_h.erl
@@ -26,6 +26,8 @@
init(make_error) ->
{error, my_error};
+init({state, State}) ->
+ {ok, State};
init([Parent]) ->
{ok, Parent}; %% We will send special responses for every handled event.
init([Parent,hibernate]) ->
@@ -83,7 +85,9 @@ terminate(swap, State) ->
{ok, State};
terminate({error, {return, faulty}}, Parent) ->
Parent ! {dummy_h, returned_error};
+terminate(_Reason, {undef_in_terminate, {Mod, Fun}}) ->
+ Mod:Fun(),
+ ok;
terminate(_Reason, _State) ->
ok.
-
diff --git a/lib/stdlib/test/erl_internal_SUITE.erl b/lib/stdlib/test/erl_internal_SUITE.erl
index 23d011e27..c4c4a0408 100644
--- a/lib/stdlib/test/erl_internal_SUITE.erl
+++ b/lib/stdlib/test/erl_internal_SUITE.erl
@@ -101,7 +101,7 @@ optional_callbacks(gen_server) ->
optional_callbacks(gen_fsm) ->
[{format_status,2}];
optional_callbacks(gen_event) ->
- [{format_status,2}];
+ [{handle_info, 2}, {terminate, 2}, {code_change, 3}, {format_status, 2}];
optional_callbacks(supervisor_bridge) ->
[];
optional_callbacks(supervisor) ->
diff --git a/lib/stdlib/test/gen_event_SUITE.erl b/lib/stdlib/test/gen_event_SUITE.erl
index 9a7400c84..3f949ca10 100644
--- a/lib/stdlib/test/gen_event_SUITE.erl
+++ b/lib/stdlib/test/gen_event_SUITE.erl
@@ -22,13 +22,17 @@
-include_lib("common_test/include/ct.hrl").
-export([all/0, suite/0,groups/0,init_per_suite/1, end_per_suite/1,
- init_per_group/2,end_per_group/2]).
+ init_per_group/2,end_per_group/2, init_per_testcase/2,
+ end_per_testcase/2]).
-export([start/1, add_handler/1, add_sup_handler/1,
delete_handler/1, swap_handler/1, swap_sup_handler/1,
notify/1, sync_notify/1, call/1, info/1, hibernate/1,
call_format_status/1, call_format_status_anon/1,
error_format_status/1, get_state/1, replace_state/1,
- start_opt/1]).
+ start_opt/1,
+ undef_init/1, undef_handle_call/1, undef_handle_event/1,
+ undef_handle_info/1, undef_code_change/1, undef_terminate/1,
+ undef_in_terminate/1]).
suite() -> [{ct_hooks,[ts_install_cth]}].
@@ -36,13 +40,16 @@ all() ->
[start, {group, test_all}, hibernate,
call_format_status, call_format_status_anon, error_format_status,
get_state, replace_state,
- start_opt].
+ start_opt, {group, undef_callbacks}, undef_in_terminate].
groups() ->
[{test_all, [],
[add_handler, add_sup_handler, delete_handler,
swap_handler, swap_sup_handler, notify, sync_notify,
- call, info]}].
+ call, info]},
+ {undef_callbacks, [],
+ [undef_init, undef_handle_call, undef_handle_event, undef_handle_info,
+ undef_code_change, undef_terminate]}].
init_per_suite(Config) ->
Config.
@@ -50,12 +57,40 @@ init_per_suite(Config) ->
end_per_suite(_Config) ->
ok.
+init_per_group(undef_callbacks, Config) ->
+ DataDir = ?config(data_dir, Config),
+ Event1 = filename:join(DataDir, "oc_event.erl"),
+ {ok, oc_event} = compile:file(Event1),
+ Config;
init_per_group(_GroupName, Config) ->
Config.
end_per_group(_GroupName, Config) ->
Config.
+init_per_testcase(Case, Config) when Case == undef_handle_call;
+ Case == undef_handle_info;
+ Case == undef_handle_event;
+ Case == undef_code_change;
+ Case == undef_terminate ->
+ {ok, Pid} = oc_event:start(),
+ [{event_pid, Pid}|Config];
+init_per_testcase(undef_init, Config) ->
+ {ok, Pid} = gen_event:start({local, oc_init_event}),
+ [{event_pid, Pid}|Config];
+init_per_testcase(_Case, Config) ->
+ Config.
+
+end_per_testcase(Case, Config) when Case == undef_init;
+ Case == undef_handle_call;
+ Case == undef_handle_info;
+ Case == undef_handle_event;
+ Case == undef_code_change;
+ Case == undef_terminate ->
+ Pid = ?config(event_pid, Config),
+ gen_event:stop(Pid);
+end_per_testcase(_Case, _Config) ->
+ ok.
%% --------------------------------------
%% Start an event manager.
@@ -1055,3 +1090,92 @@ replace_state(Config) when is_list(Config) ->
ok = sys:resume(Pid),
[{dummy1_h,false,NState3}] = sys:get_state(Pid),
ok.
+
+%% No default provided for init, so it should fail
+undef_init(Config) ->
+ Pid = ?config(event_pid, Config),
+ {'EXIT', {undef, [{oc_init_event, init, [_], _}|_]}}
+ = gen_event:add_handler(Pid, oc_init_event, []),
+ ok.
+
+%% No default provided for init, so it should fail
+undef_handle_call(Config) when is_list(Config) ->
+ Pid = ?config(event_pid, Config),
+ {error, {'EXIT', {undef, [{oc_event, handle_call, _, _}|_]}}}
+ = gen_event:call(Pid, oc_event, call_msg),
+ [] = gen_event:which_handlers(Pid),
+ ok.
+
+%% No default provided for init, so it should fail
+undef_handle_event(Config) ->
+ Pid = ?config(event_pid, Config),
+ ok = gen_event:sync_notify(Pid, event_msg),
+ [] = gen_event:which_handlers(Pid),
+
+ gen_event:add_handler(oc_event, oc_event, []),
+ [oc_event] = gen_event:which_handlers(Pid),
+
+ ok = gen_event:notify(Pid, event_msg),
+ [] = gen_event:which_handlers(Pid),
+ ok.
+
+%% Defaulting to doing nothing with a log warning.
+undef_handle_info(Config) when is_list(Config) ->
+ error_logger_forwarder:register(),
+ Pid = ?config(event_pid, Config),
+ Pid ! hej,
+ wait_until_processed(Pid, hej, 10),
+ [oc_event] = gen_event:which_handlers(Pid),
+ receive
+ {warning_msg, _GroupLeader,
+ {Pid, "** Undefined handle_info in " ++ _, [oc_event, hej]}} ->
+ ok;
+ Other ->
+ io:format("Unexpected: ~p", [Other]),
+ ct:fail(failed)
+ end.
+
+wait_until_processed(_Pid, _Message, 0) ->
+ ct:fail(not_processed);
+wait_until_processed(Pid, Message, N) ->
+ {messages, Messages} = erlang:process_info(Pid, messages),
+ case lists:member(Message, Messages) of
+ true ->
+ timer:sleep(100),
+ wait_until_processed(Pid, Message, N-1);
+ false ->
+ ok
+ end.
+
+%% No default provided for init, so it should fail
+undef_code_change(Config) when is_list(Config) ->
+ Pid = ?config(event_pid, Config),
+ {error, {'EXIT', {undef, [{oc_event, code_change, [_, _, _], _}|_]}}} =
+ fake_upgrade(Pid, oc_event),
+ [oc_event] = gen_event:which_handlers(Pid),
+ ok.
+
+%% Defaulting to doing nothing. Test that it works when not defined.
+undef_terminate(Config) when is_list(Config) ->
+ Pid = ?config(event_pid, Config),
+ ok = gen_event:delete_handler(Pid, oc_event, []),
+ [] = gen_event:which_handlers(Pid),
+ ok.
+
+%% Test that the default implementation doesn't catch the wrong undef error
+undef_in_terminate(_Config) ->
+ {ok, Pid} = gen_event:start({local, dummy}),
+ State = {undef_in_terminate, {dummy_h, terminate}},
+ ok = gen_event:add_handler(Pid, dummy_h, {state, State}),
+ [dummy_h] = gen_event:which_handlers(Pid),
+ {'EXIT', {undef, [{dummy_h, terminate, [], []}|_]}}
+ = gen_event:delete_handler(Pid, dummy_h, []),
+ [] = gen_event:which_handlers(Pid),
+ ok.
+
+fake_upgrade(Pid, Mod) ->
+ sys:suspend(Pid),
+ sys:replace_state(Pid, fun(S) -> {new, S} end),
+ Ret = sys:change_code(Pid, Mod, old_vsn, []),
+ ok = sys:resume(Pid),
+ Ret.
diff --git a/lib/stdlib/test/gen_event_SUITE_data/oc_event.erl b/lib/stdlib/test/gen_event_SUITE_data/oc_event.erl
new file mode 100644
index 000000000..eb664ef55
--- /dev/null
+++ b/lib/stdlib/test/gen_event_SUITE_data/oc_event.erl
@@ -0,0 +1,40 @@
+%%
+%% %CopyrightBegin%
+%%
+%% Copyright Ericsson AB 2017. All Rights Reserved.
+%%
+%% Licensed under the Apache License, Version 2.0 (the "License");
+%% you may not use this file except in compliance with the License.
+%% You may obtain a copy of the License at
+%%
+%% http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing, software
+%% distributed under the License is distributed on an "AS IS" BASIS,
+%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+%% See the License for the specific language governing permissions and
+%% limitations under the License.
+%%
+%% %CopyrightEnd%
+%%
+-module(oc_event).
+
+-behaviour(gen_event).
+
+%% API
+-export([start/0]).
+
+%% gen_event callbacks
+-export([init/1]).
+
+-define(SERVER, ?MODULE).
+
+-record(state, {}).
+
+start() ->
+ {ok, Pid} = gen_event:start({local, ?SERVER}),
+ gen_event:add_handler(?SERVER, ?MODULE, []),
+ {ok, Pid}.
+
+init([]) ->
+ {ok, #state{}}.
--
2.12.2
