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2347-stdlib-Make-gen_event-callbacks-optional.p...
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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
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