From 6c298a7bfa332e5b7d153648d741740abc3bcdf8 Mon Sep 17 00:00:00 2001 From: Steve Vinoski Date: Wed, 19 Mar 2014 11:45:11 -0400 Subject: fix sys:get_state/1,2 and sys:replace_state/2,3 when sys suspended Add two new system callbacks Module:system_get_state/1 and Module:system_replace_state/2 to allow sys:get_state/1,2 and sys:replace_state/2,3 to operate correctly even if a process is sys suspended. Modify gen_server, gen_fsm, and gen_event to support the new callbacks. If a callback module does not export these functions, then by default the Misc value (the same as that passed as the final argument to sys:handle_system_msg/6, and returned as part of the return value of sys:get_status/1,2) is treated as the callback module's state. The previous behaviour of intercepting the system message and passing a tuple of size 2 as the last argument to sys:handle_system_msg/6 is no longer supported. Add tests to verify the correctness of sys:get_state/1,2 and sys:replace_state/2,3 when processes are sys suspended. Add two tests for modules that implement special processes, one that exports system_get_state/1 and system_replace_state/2 and one that doesn't. Much of the credit for this patch goes to James Fish, who reported the initial problem and implemented much of the fix. --- lib/stdlib/src/gen_event.erl | 37 ++++++++++++------------ lib/stdlib/src/gen_fsm.erl | 20 ++++++------- lib/stdlib/src/gen_server.erl | 16 ++++++----- lib/stdlib/src/sys.erl | 65 +++++++++++++++++++++++++++++++++++++------ 4 files changed, 94 insertions(+), 44 deletions(-) (limited to 'lib/stdlib/src') diff --git a/lib/stdlib/src/gen_event.erl b/lib/stdlib/src/gen_event.erl index 7629e88fbf..d39dd89d3a 100644 --- a/lib/stdlib/src/gen_event.erl +++ b/lib/stdlib/src/gen_event.erl @@ -40,6 +40,8 @@ system_continue/3, system_terminate/4, system_code_change/4, + system_get_state/1, + system_replace_state/2, format_status/2]). -export_type([handler/0, handler_args/0, add_handler_ret/0, @@ -229,24 +231,6 @@ wake_hib(Parent, ServerName, MSL, Debug) -> fetch_msg(Parent, ServerName, MSL, Debug, Hib) -> receive - {system, From, get_state} -> - States = [{Mod,Id,State} || #handler{module=Mod, id=Id, state=State} <- MSL], - sys:handle_system_msg(get_state, From, Parent, ?MODULE, Debug, - {States, [ServerName, MSL, Hib]}, Hib); - {system, From, {replace_state, StateFun}} -> - {NMSL, NStates} = - lists:unzip([begin - Cur = {Mod,Id,State}, - try - NState = {Mod,Id,NS} = StateFun(Cur), - {HS#handler{state=NS}, NState} - catch - _:_ -> - {HS, Cur} - end - end || #handler{module=Mod, id=Id, state=State}=HS <- MSL]), - sys:handle_system_msg(replace_state, From, Parent, ?MODULE, Debug, - {NStates, [ServerName, NMSL, Hib]}, Hib); {system, From, Req} -> sys:handle_system_msg(Req, From, Parent, ?MODULE, Debug, [ServerName, MSL, Hib],Hib); @@ -383,6 +367,23 @@ system_code_change([ServerName, MSL, Hib], Module, OldVsn, Extra) -> MSL), {ok, [ServerName, MSL1, Hib]}. +system_get_state([_ServerName, MSL, _Hib]) -> + {ok, [{Mod,Id,State} || #handler{module=Mod, id=Id, state=State} <- MSL]}. + +system_replace_state(StateFun, [ServerName, MSL, Hib]) -> + {NMSL, NStates} = + lists:unzip([begin + Cur = {Mod,Id,State}, + try + NState = {Mod,Id,NS} = StateFun(Cur), + {HS#handler{state=NS}, NState} + catch + _:_ -> + {HS, Cur} + end + end || #handler{module=Mod, id=Id, state=State}=HS <- MSL]), + {ok, NStates, [ServerName, NMSL, Hib]}. + %%----------------------------------------------------------------- %% Format debug messages. Print them as the call-back module sees %% them, not as the real erlang messages. Use trace for that. diff --git a/lib/stdlib/src/gen_fsm.erl b/lib/stdlib/src/gen_fsm.erl index e9654322f1..e914f7d0b2 100644 --- a/lib/stdlib/src/gen_fsm.erl +++ b/lib/stdlib/src/gen_fsm.erl @@ -118,6 +118,8 @@ system_continue/3, system_terminate/4, system_code_change/4, + system_get_state/1, + system_replace_state/2, format_status/2]). -import(error_logger, [format/2]). @@ -422,17 +424,6 @@ wake_hib(Parent, Name, StateName, StateData, Mod, Debug) -> decode_msg(Msg,Parent, Name, StateName, StateData, Mod, Time, Debug, Hib) -> case Msg of - {system, From, get_state} -> - Misc = [Name, StateName, StateData, Mod, Time], - sys:handle_system_msg(get_state, From, Parent, ?MODULE, Debug, - {{StateName, StateData}, Misc}, Hib); - {system, From, {replace_state, StateFun}} -> - State = {StateName, StateData}, - NState = {NStateName, NStateData} = try StateFun(State) - catch _:_ -> State end, - NMisc = [Name, NStateName, NStateData, Mod, Time], - sys:handle_system_msg(replace_state, From, Parent, ?MODULE, Debug, - {NState, NMisc}, Hib); {system, From, Req} -> sys:handle_system_msg(Req, From, Parent, ?MODULE, Debug, [Name, StateName, StateData, Mod, Time], Hib); @@ -467,6 +458,13 @@ system_code_change([Name, StateName, StateData, Mod, Time], Else -> Else end. +system_get_state([_Name, StateName, StateData, _Mod, _Time]) -> + {ok, {StateName, StateData}}. + +system_replace_state(StateFun, [Name, StateName, StateData, Mod, Time]) -> + Result = {NStateName, NStateData} = StateFun({StateName, StateData}), + {ok, Result, [Name, NStateName, NStateData, Mod, Time]}. + %%----------------------------------------------------------------- %% Format debug messages. Print them as the call-back module sees %% them, not as the real erlang messages. Use trace for that. diff --git a/lib/stdlib/src/gen_server.erl b/lib/stdlib/src/gen_server.erl index 5f14e48b0a..202a931fae 100644 --- a/lib/stdlib/src/gen_server.erl +++ b/lib/stdlib/src/gen_server.erl @@ -98,6 +98,8 @@ -export([system_continue/3, system_terminate/4, system_code_change/4, + system_get_state/1, + system_replace_state/2, format_status/2]). %% Internal exports @@ -372,13 +374,6 @@ wake_hib(Parent, Name, State, Mod, Debug) -> decode_msg(Msg, Parent, Name, State, Mod, Time, Debug, Hib) -> case Msg of - {system, From, get_state} -> - sys:handle_system_msg(get_state, From, Parent, ?MODULE, Debug, - {State, [Name, State, Mod, Time]}, Hib); - {system, From, {replace_state, StateFun}} -> - NState = try StateFun(State) catch _:_ -> State end, - sys:handle_system_msg(replace_state, From, Parent, ?MODULE, Debug, - {NState, [Name, NState, Mod, Time]}, Hib); {system, From, Req} -> sys:handle_system_msg(Req, From, Parent, ?MODULE, Debug, [Name, State, Mod, Time], Hib); @@ -687,6 +682,13 @@ system_code_change([Name, State, Mod, Time], _Module, OldVsn, Extra) -> Else -> Else end. +system_get_state([_Name, State, _Mod, _Time]) -> + {ok, State}. + +system_replace_state(StateFun, [Name, State, Mod, Time]) -> + NState = StateFun(State), + {ok, NState, [Name, NState, Mod, Time]}. + %%----------------------------------------------------------------- %% Format debug messages. Print them as the call-back module sees %% them, not as the real erlang messages. Use trace for that. diff --git a/lib/stdlib/src/sys.erl b/lib/stdlib/src/sys.erl index 04f8dfb61b..e25cc25f57 100644 --- a/lib/stdlib/src/sys.erl +++ b/lib/stdlib/src/sys.erl @@ -102,20 +102,31 @@ get_status(Name, Timeout) -> send_system_msg(Name, get_status, Timeout). -spec get_state(Name) -> State when Name :: name(), State :: term(). -get_state(Name) -> send_system_msg(Name, get_state). +get_state(Name) -> + case send_system_msg(Name, get_state) of + {error, Reason} -> error(Reason); + State -> State + end. -spec get_state(Name, Timeout) -> State when Name :: name(), Timeout :: timeout(), State :: term(). -get_state(Name, Timeout) -> send_system_msg(Name, get_state, Timeout). +get_state(Name, Timeout) -> + case send_system_msg(Name, get_state, Timeout) of + {error, Reason} -> error(Reason); + State -> State + end. -spec replace_state(Name, StateFun) -> NewState when Name :: name(), StateFun :: fun((State :: term()) -> NewState :: term()), NewState :: term(). replace_state(Name, StateFun) -> - send_system_msg(Name, {replace_state, StateFun}). + case send_system_msg(Name, {replace_state, StateFun}) of + {error, Reason} -> error(Reason); + State -> State + end. -spec replace_state(Name, StateFun, Timeout) -> NewState when Name :: name(), @@ -123,7 +134,10 @@ replace_state(Name, StateFun) -> Timeout :: timeout(), NewState :: term(). replace_state(Name, StateFun, Timeout) -> - send_system_msg(Name, {replace_state, StateFun}, Timeout). + case send_system_msg(Name, {replace_state, StateFun}, Timeout) of + {error, Reason} -> error(Reason); + State -> State + end. -spec change_code(Name, Module, OldVsn, Extra) -> 'ok' | {error, Reason} when Name :: name(), @@ -390,10 +404,11 @@ do_cmd(_, suspend, _Parent, _Mod, Debug, Misc) -> {suspended, ok, Debug, Misc}; do_cmd(_, resume, _Parent, _Mod, Debug, Misc) -> {running, ok, Debug, Misc}; -do_cmd(SysState, get_state, _Parent, _Mod, Debug, {State, Misc}) -> - {SysState, State, Debug, Misc}; -do_cmd(SysState, replace_state, _Parent, _Mod, Debug, {State, Misc}) -> - {SysState, State, Debug, Misc}; +do_cmd(SysState, get_state, _Parent, Mod, Debug, Misc) -> + {SysState, do_get_state(Mod, Misc), Debug, Misc}; +do_cmd(SysState, {replace_state, StateFun}, _Parent, Mod, Debug, Misc) -> + {Res, NMisc} = do_replace_state(StateFun, Mod, Misc), + {SysState, Res, Debug, NMisc}; do_cmd(SysState, get_status, Parent, Mod, Debug, Misc) -> Res = get_status(SysState, Parent, Mod, Debug, Misc), {SysState, Res, Debug, Misc}; @@ -407,6 +422,40 @@ do_cmd(suspended, {change_code, Module, Vsn, Extra}, _Parent, do_cmd(SysState, Other, _Parent, _Mod, Debug, Misc) -> {SysState, {error, {unknown_system_msg, Other}}, Debug, Misc}. +do_get_state(Mod, Misc) -> + case erlang:function_exported(Mod, system_get_state, 1) of + true -> + try + {ok, State} = Mod:system_get_state(Misc), + State + catch + Cl:Exc -> + {error, {callback_failed,{Mod,system_get_state},{Cl,Exc}}} + end; + false -> + Misc + end. + +do_replace_state(StateFun, Mod, Misc) -> + case erlang:function_exported(Mod, system_replace_state, 2) of + true -> + try + {ok, State, NMisc} = Mod:system_replace_state(StateFun, Misc), + {State, NMisc} + catch + Cl:Exc -> + {{error, {callback_failed,{Mod,system_replace_state},{Cl,Exc}}}, Misc} + end; + false -> + try + NMisc = StateFun(Misc), + {NMisc, NMisc} + catch + Cl:Exc -> + {{error, {callback_failed,StateFun,{Cl,Exc}}}, Misc} + end + end. + get_status(SysState, Parent, Mod, Debug, Misc) -> PDict = get(), FmtMisc = -- cgit v1.2.3