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2348-stdlib-Make-gen_fsm-callbacks-optional.patch
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File 2348-stdlib-Make-gen_fsm-callbacks-optional.patch of Package erlang
From 215f61f223a07493d1147a04375d11f3c7819e42 Mon Sep 17 00:00:00 2001 From: Zandra Norman <zandra@erlang.org> Date: Tue, 24 Jan 2017 13:40:21 +0100 Subject: [PATCH 3/4] stdlib: Make gen_fsm callbacks optional --- lib/stdlib/doc/src/gen_fsm.xml | 19 ++++ lib/stdlib/src/gen_fsm.erl | 47 +++++--- lib/stdlib/test/erl_internal_SUITE.erl | 2 +- lib/stdlib/test/gen_fsm_SUITE.erl | 151 +++++++++++++++++++++++++- lib/stdlib/test/gen_fsm_SUITE_data/oc_fsm.erl | 48 ++++++++ 5 files changed, 244 insertions(+), 23 deletions(-) create mode 100644 lib/stdlib/test/gen_fsm_SUITE_data/oc_fsm.erl diff --git a/lib/stdlib/doc/src/gen_fsm.xml b/lib/stdlib/doc/src/gen_fsm.xml index 719ab2b55..691a039e3 100644 --- a/lib/stdlib/doc/src/gen_fsm.xml +++ b/lib/stdlib/doc/src/gen_fsm.xml @@ -562,6 +562,13 @@ gen_fsm:sync_send_all_state_event -----> Module:handle_sync_event/4 <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/4</c> + isn't implemented the process will crash with an <c>undef</c> exit + reason.</p> + </note> <p>This function is called by a <c>gen_fsm</c> process when it is to update its internal state data during a release upgrade/downgrade, that is, when instruction <c>{update,Module,Change,...}</c>, @@ -686,6 +693,13 @@ gen_fsm:sync_send_all_state_event -----> Module:handle_sync_event/4 <v> Reason = normal | term()</v> </type> <desc> + <note> + <p>This callback is optional, so callback modules need not + export it. The <c>gen_fsm</c> module provides a default + implementation of this function that logs about the unexpected + <c>Info</c> message, drops it and returns + <c>{next_state, StateName, StateData}</c>.</p> + </note> <p>This function is called by a <c>gen_fsm</c> process when it receives any other message than a synchronous or asynchronous event (or a system message).</p> @@ -899,6 +913,11 @@ gen_fsm:sync_send_all_state_event -----> Module:handle_sync_event/4 <v>StateData = term()</v> </type> <desc> + <note> + <p>This callback is optional, so callback modules need not + export it. The <c>gen_fsm</c> module provides a default + implementation without cleanup.</p> + </note> <p>This function is called by a <c>gen_fsm</c> process when it is about to terminate. 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_fsm.erl b/lib/stdlib/src/gen_fsm.erl index e925a75fe..39a8fd42f 100644 --- a/lib/stdlib/src/gen_fsm.erl +++ b/lib/stdlib/src/gen_fsm.erl @@ -169,7 +169,8 @@ State :: term(), Status :: term(). --optional_callbacks([format_status/2]). +-optional_callbacks( + [handle_info/3, terminate/3, code_change/4, format_status/2]). %%% --------------------------------------------------- %%% Starts a generic state machine. @@ -466,6 +467,10 @@ handle_msg(Msg, Parent, Name, StateName, StateData, Mod, _Time) -> %No debug her StateName, NStateData, [])), reply(From, Reply), exit(R); + {'EXIT', {undef, [{Mod, handle_info, [_,_,_], _}|_]}} -> + error_logger:warning_msg("** Undefined handle_info in ~p~n" + "** Unhandled message: ~p~n", [Mod, Msg]), + loop(Parent, Name, StateName, StateData, Mod, infinity, []); {'EXIT', What} -> terminate(What, Name, Msg, Mod, StateName, StateData, []); Reply -> @@ -540,24 +545,30 @@ reply(Name, {To, Tag}, Reply, Debug, StateName) -> -spec terminate(term(), _, _, atom(), _, _, _) -> no_return(). terminate(Reason, Name, Msg, Mod, StateName, StateData, Debug) -> - case catch Mod:terminate(Reason, StateName, StateData) of - {'EXIT', R} -> - FmtStateData = format_status(terminate, Mod, get(), StateData), - error_info(R, Name, Msg, StateName, FmtStateData, Debug), - exit(R); - _ -> - case Reason of - normal -> - exit(normal); - shutdown -> - exit(shutdown); - {shutdown,_}=Shutdown -> - exit(Shutdown); + case erlang:function_exported(Mod, terminate, 3) of + true -> + case catch Mod:terminate(Reason, StateName, StateData) of + {'EXIT', R} -> + FmtStateData = format_status(terminate, Mod, get(), StateData), + error_info(R, Name, Msg, StateName, FmtStateData, Debug), + exit(R); _ -> - FmtStateData = format_status(terminate, Mod, get(), StateData), - error_info(Reason,Name,Msg,StateName,FmtStateData,Debug), - exit(Reason) - end + ok + end; + false -> + ok + end, + case Reason of + normal -> + exit(normal); + shutdown -> + exit(shutdown); + {shutdown,_}=Shutdown -> + exit(Shutdown); + _ -> + FmtStateData1 = format_status(terminate, Mod, get(), StateData), + error_info(Reason,Name,Msg,StateName,FmtStateData1,Debug), + exit(Reason) end. error_info(Reason, Name, Msg, StateName, StateData, Debug) -> diff --git a/lib/stdlib/test/erl_internal_SUITE.erl b/lib/stdlib/test/erl_internal_SUITE.erl index c4c4a0408..099f21f90 100644 --- a/lib/stdlib/test/erl_internal_SUITE.erl +++ b/lib/stdlib/test/erl_internal_SUITE.erl @@ -99,7 +99,7 @@ optional_callbacks(application) -> optional_callbacks(gen_server) -> [{handle_info, 2}, {terminate, 2}, {code_change, 3}, {format_status, 2}]; optional_callbacks(gen_fsm) -> - [{format_status,2}]; + [{handle_info, 3}, {terminate, 3}, {code_change, 4}, {format_status, 2}]; optional_callbacks(gen_event) -> [{handle_info, 2}, {terminate, 2}, {code_change, 3}, {format_status, 2}]; optional_callbacks(supervisor_bridge) -> diff --git a/lib/stdlib/test/gen_fsm_SUITE.erl b/lib/stdlib/test/gen_fsm_SUITE.erl index d6bb002b5..361680a9b 100644 --- a/lib/stdlib/test/gen_fsm_SUITE.erl +++ b/lib/stdlib/test/gen_fsm_SUITE.erl @@ -39,6 +39,11 @@ call_format_status/1, error_format_status/1, terminate_crash_format/1, get_state/1, replace_state/1]). +-export([undef_handle_event/1, undef_handle_sync_event/1, undef_handle_info/1, + undef_init/1, undef_code_change/1, undef_terminate1/1, undef_terminate2/1]). + +-export([undef_in_handle_info/1, undef_in_terminate/1]). + -export([hibernate/1,hiber_idle/3,hiber_wakeup/3,hiber_idle/2,hiber_wakeup/2]). -export([enter_loop/1]). @@ -48,7 +53,7 @@ %% The gen_fsm behaviour -export([init/1, handle_event/3, handle_sync_event/4, terminate/3, - handle_info/3, format_status/2]). + handle_info/3, format_status/2, code_change/4]). -export([idle/2, idle/3, timeout/2, wfor_conf/2, wfor_conf/3, @@ -63,7 +68,8 @@ suite() -> [{ct_hooks,[ts_install_cth]}]. all() -> [{group, start}, {group, abnormal}, shutdown, - {group, sys}, hibernate, enter_loop]. + {group, sys}, hibernate, enter_loop, {group, undef_callbacks}, + undef_in_handle_info, undef_in_terminate]. groups() -> [{start, [], @@ -74,7 +80,10 @@ groups() -> {abnormal, [], [abnormal1, abnormal2]}, {sys, [], [sys1, call_format_status, error_format_status, terminate_crash_format, - get_state, replace_state]}]. + get_state, replace_state]}, + {undef_callbacks, [], + [undef_handle_event, undef_handle_sync_event, undef_handle_info, + undef_init, undef_code_change, undef_terminate1, undef_terminate2]}]. init_per_suite(Config) -> Config. @@ -82,6 +91,11 @@ init_per_suite(Config) -> end_per_suite(_Config) -> ok. +init_per_group(undef_callbacks, Config) -> + DataDir = ?config(data_dir, Config), + Server = filename:join(DataDir, "oc_fsm.erl"), + {ok, oc_fsm} = compile:file(Server), + Config; init_per_group(_GroupName, Config) -> Config. @@ -868,6 +882,99 @@ enter_loop(Reg1, Reg2) -> gen_fsm:enter_loop(?MODULE, [], state0, []) end. +%% Start should return an undef error if init isn't implemented +undef_init(Config) when is_list(Config) -> + {error, {undef, [{oc_init_fsm, init, [[]], []}|_]}} + = gen_fsm:start(oc_init_fsm, [], []), + ok. + +%% Test that the server crashes correctly if the handle_event callback is +%% not exported in the callback module +undef_handle_event(Config) when is_list(Config) -> + {ok, FSM} = gen_fsm:start(oc_fsm, [], []), + MRef = monitor(process, FSM), + gen_fsm:send_all_state_event(FSM, state_name), + ok = verify_undef_down(MRef, FSM, oc_fsm, handle_event). + +%% Test that the server crashes correctly if the handle_sync_event callback is +%% not exported in the callback module +undef_handle_sync_event(Config) when is_list(Config) -> + {ok, FSM} = gen_fsm:start(oc_fsm, [], []), + try + gen_fsm:sync_send_all_state_event(FSM, state_name), + ct:fail(should_crash) + catch exit:{{undef, [{oc_fsm, handle_sync_event, _, _}|_]},_} -> + ok + end. + +%% The fsm should log but not crash if the handle_info callback is +%% calling an undefined function +undef_handle_info(Config) when is_list(Config) -> + error_logger_forwarder:register(), + {ok, FSM} = gen_fsm:start(oc_fsm, [], []), + MRef = monitor(process, FSM), + FSM ! hej, + receive + {'DOWN', MRef, process, FSM, _} -> + ct:fail(should_not_crash) + after 500 -> + ok + end, + receive + {warning_msg, _GroupLeader, + {FSM, "** Undefined handle_info in " ++ _, [oc_fsm, hej]}} -> + ok; + Other -> + io:format("Unexpected: ~p", [Other]), + ct:fail(failed) + end. + +%% The upgrade should fail if code_change is expected in the callback module +%% but not exported, but the fsm should continue with the old code +undef_code_change(Config) when is_list(Config) -> + {ok, FSM} = gen_fsm:start(oc_fsm, [], []), + {error, {'EXIT', {undef, [{oc_fsm, code_change, [_, _, _, _], _}|_]}}} + = fake_upgrade(FSM, oc_fsm), + ok. + +%% Test the default implementation of terminate with normal reason if the +%% callback module does not export it +undef_terminate1(Config) when is_list(Config) -> + {ok, FSM} = gen_fsm:start(oc_fsm, [], []), + MRef = monitor(process, FSM), + ok = gen_fsm:stop(FSM), + ok = verify_down_reason(MRef, FSM, normal). + +%% Test the default implementation of terminate with error reason if the +%% callback module does not export it +undef_terminate2(Config) when is_list(Config) -> + {ok, FSM} = gen_fsm:start(oc_fsm, [], []), + MRef = monitor(process, FSM), + ok = gen_fsm:stop(FSM, {error, test}, infinity), + ok = verify_down_reason(MRef, FSM, {error, test}). + +%% Test that the server crashes correctly if the handle_info callback is +%% calling an undefined function +undef_in_handle_info(Config) when is_list(Config) -> + {ok, FSM} = gen_fsm:start(?MODULE, [], []), + MRef = monitor(process, FSM), + FSM ! {call_undef_fun, {?MODULE, handle_info}}, + verify_undef_down(MRef, FSM, ?MODULE, handle_info), + ok. + +%% Test that the server crashes correctly if the terminate callback is +%% calling an undefined function +undef_in_terminate(Config) when is_list(Config) -> + State = {undef_in_terminate, {?MODULE, terminate}}, + {ok, FSM} = gen_fsm:start(?MODULE, {state_data, State}, []), + try + gen_fsm:stop(FSM), + ct:fail(failed) + catch + exit:{undef, [{?MODULE, terminate, _, _}|_]} -> + ok + end. + %% %% Functionality check %% @@ -962,7 +1069,31 @@ do_sync_disconnect(FSM) -> yes = gen_fsm:sync_send_event(FSM, disconnect), check_state(FSM, idle). +verify_down_reason(MRef, Pid, Reason) -> + receive + {'DOWN', MRef, process, Pid, Reason} -> + ok; + {'DOWN', MRef, process, Pid, Other}-> + ct:fail({wrong_down_reason, Other}) + after 5000 -> + ct:fail(should_shutdown) + end. +verify_undef_down(MRef, Pid, Mod, Fun) -> + ok = receive + {'DOWN', MRef, process, Pid, + {undef, [{Mod, Fun, _, _}|_]}} -> + ok + after 5000 -> + ct:fail(should_crash) + end. + +fake_upgrade(Pid, Mod) -> + sys:suspend(Pid), + sys:replace_state(Pid, fun(State) -> {new, State} end), + Ret = sys:change_code(Pid, Mod, old_vsn, []), + ok = sys:resume(Pid), + Ret. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %% @@ -992,6 +1123,9 @@ init(_) -> terminate(_, _State, crash_terminate) -> exit({crash, terminate}); +terminate(_, _, {undef_in_terminate, {Mod, Fun}}) -> + Mod:Fun(), + ok; terminate({From, stopped}, State, _Data) -> From ! {self(), {stopped, State}}, ok; @@ -1089,7 +1223,9 @@ handle_info(hibernate_now, _SName, _State) -> {next_state, hiber_idle, [], hibernate}; handle_info(hibernate_later, _SName, _State) -> {next_state, hiber_idle, hibernate_me, 1000}; - +handle_info({call_undef_fun, {Mod, Fun}}, State, Data) -> + Mod:Fun(), + {next_state, State, Data}; handle_info(Info, _State, Data) -> {stop, {unexpected,Info}, Data}. @@ -1134,6 +1270,13 @@ format_status(terminate, [_Pdict, StateData]) -> format_status(normal, [_Pdict, _StateData]) -> [format_status_called]. +code_change(_OldVsn, State, + {idle, {undef_in_code_change, {Mod, Fun}}} = Data, _Extra) -> + Mod:Fun(), + {ok, State, Data}; +code_change(_OldVsn, State, Data, _Extra) -> + {ok, State, Data}. + get_messages() -> receive Msg -> [Msg|get_messages()] diff --git a/lib/stdlib/test/gen_fsm_SUITE_data/oc_fsm.erl b/lib/stdlib/test/gen_fsm_SUITE_data/oc_fsm.erl new file mode 100644 index 000000000..27fb1bc3b --- /dev/null +++ b/lib/stdlib/test/gen_fsm_SUITE_data/oc_fsm.erl @@ -0,0 +1,48 @@ +%% +%% %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_fsm). + +-behaviour(gen_fsm). + +%% API +-export([start/0]). + +%% gen_fsm callbacks +-export([init/1, + state_name/2, + state_name/3]). + +-define(SERVER, ?MODULE). + +-record(state, {}). + +start() -> + gen_fsm:start({local, ?SERVER}, ?MODULE, [], []). + +init([]) -> + {ok, state_name, #state{}}. + +state_name(_Event, State) -> + {next_state, state_name, State}. + +state_name(_Event, _From, State) -> + Reply = ok, + {reply, Reply, state_name, State}. + -- 2.12.2
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