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Diffstat (limited to 'src/gen_server2.erl')
| -rw-r--r-- | src/gen_server2.erl | 1349 |
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diff --git a/src/gen_server2.erl b/src/gen_server2.erl deleted file mode 100644 index d2f96b52..00000000 --- a/src/gen_server2.erl +++ /dev/null @@ -1,1349 +0,0 @@ -%% This file is a copy of gen_server.erl from the R13B-1 Erlang/OTP -%% distribution, with the following modifications: -%% -%% 1) the module name is gen_server2 -%% -%% 2) more efficient handling of selective receives in callbacks -%% gen_server2 processes drain their message queue into an internal -%% buffer before invoking any callback module functions. Messages are -%% dequeued from the buffer for processing. Thus the effective message -%% queue of a gen_server2 process is the concatenation of the internal -%% buffer and the real message queue. -%% As a result of the draining, any selective receive invoked inside a -%% callback is less likely to have to scan a large message queue. -%% -%% 3) gen_server2:cast is guaranteed to be order-preserving -%% The original code could reorder messages when communicating with a -%% process on a remote node that was not currently connected. -%% -%% 4) The callback module can optionally implement prioritise_call/4, -%% prioritise_cast/3 and prioritise_info/3. These functions take -%% Message, From, Length and State or just Message, Length and State -%% (where Length is the current number of messages waiting to be -%% processed) and return a single integer representing the priority -%% attached to the message, or 'drop' to ignore it (for -%% prioritise_cast/3 and prioritise_info/3 only). Messages with -%% higher priorities are processed before requests with lower -%% priorities. The default priority is 0. -%% -%% 5) The callback module can optionally implement -%% handle_pre_hibernate/1 and handle_post_hibernate/1. These will be -%% called immediately prior to and post hibernation, respectively. If -%% handle_pre_hibernate returns {hibernate, NewState} then the process -%% will hibernate. If the module does not implement -%% handle_pre_hibernate/1 then the default action is to hibernate. -%% -%% 6) init can return a 4th arg, {backoff, InitialTimeout, -%% MinimumTimeout, DesiredHibernatePeriod} (all in milliseconds, -%% 'infinity' does not make sense here). Then, on all callbacks which -%% can return a timeout (including init), timeout can be -%% 'hibernate'. When this is the case, the current timeout value will -%% be used (initially, the InitialTimeout supplied from init). After -%% this timeout has occurred, hibernation will occur as normal. Upon -%% awaking, a new current timeout value will be calculated. -%% -%% The purpose is that the gen_server2 takes care of adjusting the -%% current timeout value such that the process will increase the -%% timeout value repeatedly if it is unable to sleep for the -%% DesiredHibernatePeriod. If it is able to sleep for the -%% DesiredHibernatePeriod it will decrease the current timeout down to -%% the MinimumTimeout, so that the process is put to sleep sooner (and -%% hopefully stays asleep for longer). In short, should a process -%% using this receive a burst of messages, it should not hibernate -%% between those messages, but as the messages become less frequent, -%% the process will not only hibernate, it will do so sooner after -%% each message. -%% -%% When using this backoff mechanism, normal timeout values (i.e. not -%% 'hibernate') can still be used, and if they are used then the -%% handle_info(timeout, State) will be called as normal. In this case, -%% returning 'hibernate' from handle_info(timeout, State) will not -%% hibernate the process immediately, as it would if backoff wasn't -%% being used. Instead it'll wait for the current timeout as described -%% above. -%% -%% 7) The callback module can return from any of the handle_* -%% functions, a {become, Module, State} triple, or a {become, Module, -%% State, Timeout} quadruple. This allows the gen_server to -%% dynamically change the callback module. The State is the new state -%% which will be passed into any of the callback functions in the new -%% module. Note there is no form also encompassing a reply, thus if -%% you wish to reply in handle_call/3 and change the callback module, -%% you need to use gen_server2:reply/2 to issue the reply -%% manually. The init function can similarly return a 5th argument, -%% Module, in order to dynamically decide the callback module on init. -%% -%% 8) The callback module can optionally implement -%% format_message_queue/2 which is the equivalent of format_status/2 -%% but where the second argument is specifically the priority_queue -%% which contains the prioritised message_queue. -%% -%% 9) The function with_state/2 can be used to debug a process with -%% heavyweight state (without needing to copy the entire state out of -%% process as sys:get_status/1 would). Pass through a function which -%% can be invoked on the state, get back the result. The state is not -%% modified. -%% -%% 10) an mcall/1 function has been added for performing multiple -%% call/3 in parallel. Unlike multi_call, which sends the same request -%% to same-named processes residing on a supplied list of nodes, it -%% operates on name/request pairs, where name is anything accepted by -%% call/3, i.e. a pid, global name, local name, or local name on a -%% particular node. -%% - -%% All modifications are (C) 2009-2013 GoPivotal, Inc. - -%% ``The contents of this file are subject to the Erlang Public License, -%% Version 1.1, (the "License"); you may not use this file except in -%% compliance with the License. You should have received a copy of the -%% Erlang Public License along with this software. If not, it can be -%% retrieved via the world wide web at http://www.erlang.org/. -%% -%% Software distributed under the License is distributed on an "AS IS" -%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See -%% the License for the specific language governing rights and limitations -%% under the License. -%% -%% The Initial Developer of the Original Code is Ericsson Utvecklings AB. -%% Portions created by Ericsson are Copyright 1999, Ericsson Utvecklings -%% AB. All Rights Reserved.'' -%% -%% $Id$ -%% --module(gen_server2). - -%%% --------------------------------------------------- -%%% -%%% The idea behind THIS server is that the user module -%%% provides (different) functions to handle different -%%% kind of inputs. -%%% If the Parent process terminates the Module:terminate/2 -%%% function is called. -%%% -%%% The user module should export: -%%% -%%% init(Args) -%%% ==> {ok, State} -%%% {ok, State, Timeout} -%%% {ok, State, Timeout, Backoff} -%%% {ok, State, Timeout, Backoff, Module} -%%% ignore -%%% {stop, Reason} -%%% -%%% handle_call(Msg, {From, Tag}, State) -%%% -%%% ==> {reply, Reply, State} -%%% {reply, Reply, State, Timeout} -%%% {noreply, State} -%%% {noreply, State, Timeout} -%%% {stop, Reason, Reply, State} -%%% Reason = normal | shutdown | Term terminate(State) is called -%%% -%%% handle_cast(Msg, State) -%%% -%%% ==> {noreply, State} -%%% {noreply, State, Timeout} -%%% {stop, Reason, State} -%%% Reason = normal | shutdown | Term terminate(State) is called -%%% -%%% handle_info(Info, State) Info is e.g. {'EXIT', P, R}, {nodedown, N}, ... -%%% -%%% ==> {noreply, State} -%%% {noreply, State, Timeout} -%%% {stop, Reason, State} -%%% Reason = normal | shutdown | Term, terminate(State) is called -%%% -%%% terminate(Reason, State) Let the user module clean up -%%% Reason = normal | shutdown | {shutdown, Term} | Term -%%% always called when server terminates -%%% -%%% ==> ok | Term -%%% -%%% handle_pre_hibernate(State) -%%% -%%% ==> {hibernate, State} -%%% {stop, Reason, State} -%%% Reason = normal | shutdown | Term, terminate(State) is called -%%% -%%% handle_post_hibernate(State) -%%% -%%% ==> {noreply, State} -%%% {stop, Reason, State} -%%% Reason = normal | shutdown | Term, terminate(State) is called -%%% -%%% The work flow (of the server) can be described as follows: -%%% -%%% User module Generic -%%% ----------- ------- -%%% start -----> start -%%% init <----- . -%%% -%%% loop -%%% handle_call <----- . -%%% -----> reply -%%% -%%% handle_cast <----- . -%%% -%%% handle_info <----- . -%%% -%%% terminate <----- . -%%% -%%% -----> reply -%%% -%%% -%%% --------------------------------------------------- - -%% API --export([start/3, start/4, - start_link/3, start_link/4, - call/2, call/3, - cast/2, reply/2, - abcast/2, abcast/3, - multi_call/2, multi_call/3, multi_call/4, - mcall/1, - with_state/2, - enter_loop/3, enter_loop/4, enter_loop/5, enter_loop/6, wake_hib/1]). - -%% System exports --export([system_continue/3, - system_terminate/4, - system_code_change/4, - format_status/2]). - -%% Internal exports --export([init_it/6]). - --import(error_logger, [format/2]). - -%% State record --record(gs2_state, {parent, name, state, mod, time, - timeout_state, queue, debug, prioritisers}). - --ifdef(use_specs). - -%%%========================================================================= -%%% Specs. These exist only to shut up dialyzer's warnings -%%%========================================================================= - --type(gs2_state() :: #gs2_state{}). - --spec(handle_common_termination/3 :: - (any(), atom(), gs2_state()) -> no_return()). --spec(hibernate/1 :: (gs2_state()) -> no_return()). --spec(pre_hibernate/1 :: (gs2_state()) -> no_return()). --spec(system_terminate/4 :: (_, _, _, gs2_state()) -> no_return()). - --type(millis() :: non_neg_integer()). - -%%%========================================================================= -%%% API -%%%========================================================================= - --callback init(Args :: term()) -> - {ok, State :: term()} | - {ok, State :: term(), timeout() | hibernate} | - {ok, State :: term(), timeout() | hibernate, - {backoff, millis(), millis(), millis()}} | - {ok, State :: term(), timeout() | hibernate, - {backoff, millis(), millis(), millis()}, atom()} | - ignore | - {stop, Reason :: term()}. --callback handle_call(Request :: term(), From :: {pid(), Tag :: term()}, - State :: term()) -> - {reply, Reply :: term(), NewState :: term()} | - {reply, Reply :: term(), NewState :: term(), timeout() | hibernate} | - {noreply, NewState :: term()} | - {noreply, NewState :: term(), timeout() | hibernate} | - {stop, Reason :: term(), - Reply :: term(), NewState :: term()}. --callback handle_cast(Request :: term(), State :: term()) -> - {noreply, NewState :: term()} | - {noreply, NewState :: term(), timeout() | hibernate} | - {stop, Reason :: term(), NewState :: term()}. --callback handle_info(Info :: term(), State :: term()) -> - {noreply, NewState :: term()} | - {noreply, NewState :: term(), timeout() | hibernate} | - {stop, Reason :: term(), NewState :: term()}. --callback terminate(Reason :: (normal | shutdown | {shutdown, term()} | term()), - State :: term()) -> - ok | term(). --callback code_change(OldVsn :: (term() | {down, term()}), State :: term(), - Extra :: term()) -> - {ok, NewState :: term()} | {error, Reason :: term()}. - -%% It's not possible to define "optional" -callbacks, so putting specs -%% for handle_pre_hibernate/1 and handle_post_hibernate/1 will result -%% in warnings (the same applied for the behaviour_info before). - --else. - --export([behaviour_info/1]). - -behaviour_info(callbacks) -> - [{init,1},{handle_call,3},{handle_cast,2},{handle_info,2}, - {terminate,2},{code_change,3}]; -behaviour_info(_Other) -> - undefined. - --endif. - -%%% ----------------------------------------------------------------- -%%% Starts a generic server. -%%% start(Mod, Args, Options) -%%% start(Name, Mod, Args, Options) -%%% start_link(Mod, Args, Options) -%%% start_link(Name, Mod, Args, Options) where: -%%% Name ::= {local, atom()} | {global, atom()} -%%% Mod ::= atom(), callback module implementing the 'real' server -%%% Args ::= term(), init arguments (to Mod:init/1) -%%% Options ::= [{timeout, Timeout} | {debug, [Flag]}] -%%% Flag ::= trace | log | {logfile, File} | statistics | debug -%%% (debug == log && statistics) -%%% Returns: {ok, Pid} | -%%% {error, {already_started, Pid}} | -%%% {error, Reason} -%%% ----------------------------------------------------------------- -start(Mod, Args, Options) -> - gen:start(?MODULE, nolink, Mod, Args, Options). - -start(Name, Mod, Args, Options) -> - gen:start(?MODULE, nolink, Name, Mod, Args, Options). - -start_link(Mod, Args, Options) -> - gen:start(?MODULE, link, Mod, Args, Options). - -start_link(Name, Mod, Args, Options) -> - gen:start(?MODULE, link, Name, Mod, Args, Options). - - -%% ----------------------------------------------------------------- -%% Make a call to a generic server. -%% If the server is located at another node, that node will -%% be monitored. -%% If the client is trapping exits and is linked server termination -%% is handled here (? Shall we do that here (or rely on timeouts) ?). -%% ----------------------------------------------------------------- -call(Name, Request) -> - case catch gen:call(Name, '$gen_call', Request) of - {ok,Res} -> - Res; - {'EXIT',Reason} -> - exit({Reason, {?MODULE, call, [Name, Request]}}) - end. - -call(Name, Request, Timeout) -> - case catch gen:call(Name, '$gen_call', Request, Timeout) of - {ok,Res} -> - Res; - {'EXIT',Reason} -> - exit({Reason, {?MODULE, call, [Name, Request, Timeout]}}) - end. - -%% ----------------------------------------------------------------- -%% Make a cast to a generic server. -%% ----------------------------------------------------------------- -cast({global,Name}, Request) -> - catch global:send(Name, cast_msg(Request)), - ok; -cast({Name,Node}=Dest, Request) when is_atom(Name), is_atom(Node) -> - do_cast(Dest, Request); -cast(Dest, Request) when is_atom(Dest) -> - do_cast(Dest, Request); -cast(Dest, Request) when is_pid(Dest) -> - do_cast(Dest, Request). - -do_cast(Dest, Request) -> - do_send(Dest, cast_msg(Request)), - ok. - -cast_msg(Request) -> {'$gen_cast',Request}. - -%% ----------------------------------------------------------------- -%% Send a reply to the client. -%% ----------------------------------------------------------------- -reply({To, Tag}, Reply) -> - catch To ! {Tag, Reply}. - -%% ----------------------------------------------------------------- -%% Asyncronous broadcast, returns nothing, it's just send'n pray -%% ----------------------------------------------------------------- -abcast(Name, Request) when is_atom(Name) -> - do_abcast([node() | nodes()], Name, cast_msg(Request)). - -abcast(Nodes, Name, Request) when is_list(Nodes), is_atom(Name) -> - do_abcast(Nodes, Name, cast_msg(Request)). - -do_abcast([Node|Nodes], Name, Msg) when is_atom(Node) -> - do_send({Name,Node},Msg), - do_abcast(Nodes, Name, Msg); -do_abcast([], _,_) -> abcast. - -%%% ----------------------------------------------------------------- -%%% Make a call to servers at several nodes. -%%% Returns: {[Replies],[BadNodes]} -%%% A Timeout can be given -%%% -%%% A middleman process is used in case late answers arrives after -%%% the timeout. If they would be allowed to glog the callers message -%%% queue, it would probably become confused. Late answers will -%%% now arrive to the terminated middleman and so be discarded. -%%% ----------------------------------------------------------------- -multi_call(Name, Req) - when is_atom(Name) -> - do_multi_call([node() | nodes()], Name, Req, infinity). - -multi_call(Nodes, Name, Req) - when is_list(Nodes), is_atom(Name) -> - do_multi_call(Nodes, Name, Req, infinity). - -multi_call(Nodes, Name, Req, infinity) -> - do_multi_call(Nodes, Name, Req, infinity); -multi_call(Nodes, Name, Req, Timeout) - when is_list(Nodes), is_atom(Name), is_integer(Timeout), Timeout >= 0 -> - do_multi_call(Nodes, Name, Req, Timeout). - -%%% ----------------------------------------------------------------- -%%% Make multiple calls to multiple servers, given pairs of servers -%%% and messages. -%%% Returns: {[{Dest, Reply}], [{Dest, Error}]} -%%% -%%% Dest can be pid() | RegName :: atom() | -%%% {Name :: atom(), Node :: atom()} | {global, Name :: atom()} -%%% -%%% A middleman process is used to avoid clogging up the callers -%%% message queue. -%%% ----------------------------------------------------------------- -mcall(CallSpecs) -> - Tag = make_ref(), - {_, MRef} = spawn_monitor( - fun() -> - Refs = lists:foldl( - fun ({Dest, _Request}=S, Dict) -> - dict:store(do_mcall(S), Dest, Dict) - end, dict:new(), CallSpecs), - collect_replies(Tag, Refs, [], []) - end), - receive - {'DOWN', MRef, _, _, {Tag, Result}} -> Result; - {'DOWN', MRef, _, _, Reason} -> exit(Reason) - end. - -do_mcall({{global,Name}=Dest, Request}) -> - %% whereis_name is simply an ets lookup, and is precisely what - %% global:send/2 does, yet we need a Ref to put in the call to the - %% server, so invoking whereis_name makes a lot more sense here. - case global:whereis_name(Name) of - Pid when is_pid(Pid) -> - MRef = erlang:monitor(process, Pid), - catch msend(Pid, MRef, Request), - MRef; - undefined -> - Ref = make_ref(), - self() ! {'DOWN', Ref, process, Dest, noproc}, - Ref - end; -do_mcall({{Name,Node}=Dest, Request}) when is_atom(Name), is_atom(Node) -> - {_Node, MRef} = start_monitor(Node, Name), %% NB: we don't handle R6 - catch msend(Dest, MRef, Request), - MRef; -do_mcall({Dest, Request}) when is_atom(Dest); is_pid(Dest) -> - MRef = erlang:monitor(process, Dest), - catch msend(Dest, MRef, Request), - MRef. - -msend(Dest, MRef, Request) -> - erlang:send(Dest, {'$gen_call', {self(), MRef}, Request}, [noconnect]). - -collect_replies(Tag, Refs, Replies, Errors) -> - case dict:size(Refs) of - 0 -> exit({Tag, {Replies, Errors}}); - _ -> receive - {MRef, Reply} -> - {Refs1, Replies1} = handle_call_result(MRef, Reply, - Refs, Replies), - collect_replies(Tag, Refs1, Replies1, Errors); - {'DOWN', MRef, _, _, Reason} -> - Reason1 = case Reason of - noconnection -> nodedown; - _ -> Reason - end, - {Refs1, Errors1} = handle_call_result(MRef, Reason1, - Refs, Errors), - collect_replies(Tag, Refs1, Replies, Errors1) - end - end. - -handle_call_result(MRef, Result, Refs, AccList) -> - %% we avoid the mailbox scanning cost of a call to erlang:demonitor/{1,2} - %% here, so we must cope with MRefs that we've already seen and erased - case dict:find(MRef, Refs) of - {ok, Pid} -> {dict:erase(MRef, Refs), [{Pid, Result}|AccList]}; - _ -> {Refs, AccList} - end. - -%% ----------------------------------------------------------------- -%% Apply a function to a generic server's state. -%% ----------------------------------------------------------------- -with_state(Name, Fun) -> - case catch gen:call(Name, '$with_state', Fun, infinity) of - {ok,Res} -> - Res; - {'EXIT',Reason} -> - exit({Reason, {?MODULE, with_state, [Name, Fun]}}) - end. - -%%----------------------------------------------------------------- -%% enter_loop(Mod, Options, State, <ServerName>, <TimeOut>, <Backoff>) ->_ -%% -%% Description: Makes an existing process into a gen_server. -%% The calling process will enter the gen_server receive -%% loop and become a gen_server process. -%% The process *must* have been started using one of the -%% start functions in proc_lib, see proc_lib(3). -%% The user is responsible for any initialization of the -%% process, including registering a name for it. -%%----------------------------------------------------------------- -enter_loop(Mod, Options, State) -> - enter_loop(Mod, Options, State, self(), infinity, undefined). - -enter_loop(Mod, Options, State, Backoff = {backoff, _, _ , _}) -> - enter_loop(Mod, Options, State, self(), infinity, Backoff); - -enter_loop(Mod, Options, State, ServerName = {_, _}) -> - enter_loop(Mod, Options, State, ServerName, infinity, undefined); - -enter_loop(Mod, Options, State, Timeout) -> - enter_loop(Mod, Options, State, self(), Timeout, undefined). - -enter_loop(Mod, Options, State, ServerName, Backoff = {backoff, _, _, _}) -> - enter_loop(Mod, Options, State, ServerName, infinity, Backoff); - -enter_loop(Mod, Options, State, ServerName, Timeout) -> - enter_loop(Mod, Options, State, ServerName, Timeout, undefined). - -enter_loop(Mod, Options, State, ServerName, Timeout, Backoff) -> - Name = get_proc_name(ServerName), - Parent = get_parent(), - Debug = debug_options(Name, Options), - Queue = priority_queue:new(), - Backoff1 = extend_backoff(Backoff), - loop(find_prioritisers( - #gs2_state { parent = Parent, name = Name, state = State, - mod = Mod, time = Timeout, timeout_state = Backoff1, - queue = Queue, debug = Debug })). - -%%%======================================================================== -%%% Gen-callback functions -%%%======================================================================== - -%%% --------------------------------------------------- -%%% Initiate the new process. -%%% Register the name using the Rfunc function -%%% Calls the Mod:init/Args function. -%%% Finally an acknowledge is sent to Parent and the main -%%% loop is entered. -%%% --------------------------------------------------- -init_it(Starter, self, Name, Mod, Args, Options) -> - init_it(Starter, self(), Name, Mod, Args, Options); -init_it(Starter, Parent, Name0, Mod, Args, Options) -> - Name = name(Name0), - Debug = debug_options(Name, Options), - Queue = priority_queue:new(), - GS2State = find_prioritisers( - #gs2_state { parent = Parent, - name = Name, - mod = Mod, - queue = Queue, - debug = Debug }), - case catch Mod:init(Args) of - {ok, State} -> - proc_lib:init_ack(Starter, {ok, self()}), - loop(GS2State #gs2_state { state = State, - time = infinity, - timeout_state = undefined }); - {ok, State, Timeout} -> - proc_lib:init_ack(Starter, {ok, self()}), - loop(GS2State #gs2_state { state = State, - time = Timeout, - timeout_state = undefined }); - {ok, State, Timeout, Backoff = {backoff, _, _, _}} -> - Backoff1 = extend_backoff(Backoff), - proc_lib:init_ack(Starter, {ok, self()}), - loop(GS2State #gs2_state { state = State, - time = Timeout, - timeout_state = Backoff1 }); - {ok, State, Timeout, Backoff = {backoff, _, _, _}, Mod1} -> - Backoff1 = extend_backoff(Backoff), - proc_lib:init_ack(Starter, {ok, self()}), - loop(GS2State #gs2_state { mod = Mod1, - state = State, - time = Timeout, - timeout_state = Backoff1 }); - {stop, Reason} -> - %% For consistency, we must make sure that the - %% registered name (if any) is unregistered before - %% the parent process is notified about the failure. - %% (Otherwise, the parent process could get - %% an 'already_started' error if it immediately - %% tried starting the process again.) - unregister_name(Name0), - proc_lib:init_ack(Starter, {error, Reason}), - exit(Reason); - ignore -> - unregister_name(Name0), - proc_lib:init_ack(Starter, ignore), - exit(normal); - {'EXIT', Reason} -> - unregister_name(Name0), - proc_lib:init_ack(Starter, {error, Reason}), - exit(Reason); - Else -> - Error = {bad_return_value, Else}, - proc_lib:init_ack(Starter, {error, Error}), - exit(Error) - end. - -name({local,Name}) -> Name; -name({global,Name}) -> Name; -%% name(Pid) when is_pid(Pid) -> Pid; -%% when R12 goes away, drop the line beneath and uncomment the line above -name(Name) -> Name. - -unregister_name({local,Name}) -> - _ = (catch unregister(Name)); -unregister_name({global,Name}) -> - _ = global:unregister_name(Name); -unregister_name(Pid) when is_pid(Pid) -> - Pid; -%% Under R12 let's just ignore it, as we have a single term as Name. -%% On R13 it will never get here, as we get tuple with 'local/global' atom. -unregister_name(_Name) -> ok. - -extend_backoff(undefined) -> - undefined; -extend_backoff({backoff, InitialTimeout, MinimumTimeout, DesiredHibPeriod}) -> - {backoff, InitialTimeout, MinimumTimeout, DesiredHibPeriod, now()}. - -%%%======================================================================== -%%% Internal functions -%%%======================================================================== -%%% --------------------------------------------------- -%%% The MAIN loop. -%%% --------------------------------------------------- -loop(GS2State = #gs2_state { time = hibernate, - timeout_state = undefined }) -> - pre_hibernate(GS2State); -loop(GS2State) -> - process_next_msg(drain(GS2State)). - -drain(GS2State) -> - receive - Input -> drain(in(Input, GS2State)) - after 0 -> GS2State - end. - -process_next_msg(GS2State = #gs2_state { time = Time, - timeout_state = TimeoutState, - queue = Queue }) -> - case priority_queue:out(Queue) of - {{value, Msg}, Queue1} -> - process_msg(Msg, GS2State #gs2_state { queue = Queue1 }); - {empty, Queue1} -> - {Time1, HibOnTimeout} - = case {Time, TimeoutState} of - {hibernate, {backoff, Current, _Min, _Desired, _RSt}} -> - {Current, true}; - {hibernate, _} -> - %% wake_hib/7 will set Time to hibernate. If - %% we were woken and didn't receive a msg - %% then we will get here and need a sensible - %% value for Time1, otherwise we crash. - %% R13B1 always waits infinitely when waking - %% from hibernation, so that's what we do - %% here too. - {infinity, false}; - _ -> {Time, false} - end, - receive - Input -> - %% Time could be 'hibernate' here, so *don't* call loop - process_next_msg( - drain(in(Input, GS2State #gs2_state { queue = Queue1 }))) - after Time1 -> - case HibOnTimeout of - true -> - pre_hibernate( - GS2State #gs2_state { queue = Queue1 }); - false -> - process_msg(timeout, - GS2State #gs2_state { queue = Queue1 }) - end - end - end. - -wake_hib(GS2State = #gs2_state { timeout_state = TS }) -> - TimeoutState1 = case TS of - undefined -> - undefined; - {SleptAt, TimeoutState} -> - adjust_timeout_state(SleptAt, now(), TimeoutState) - end, - post_hibernate( - drain(GS2State #gs2_state { timeout_state = TimeoutState1 })). - -hibernate(GS2State = #gs2_state { timeout_state = TimeoutState }) -> - TS = case TimeoutState of - undefined -> undefined; - {backoff, _, _, _, _} -> {now(), TimeoutState} - end, - proc_lib:hibernate(?MODULE, wake_hib, - [GS2State #gs2_state { timeout_state = TS }]). - -pre_hibernate(GS2State = #gs2_state { state = State, - mod = Mod }) -> - case erlang:function_exported(Mod, handle_pre_hibernate, 1) of - true -> - case catch Mod:handle_pre_hibernate(State) of - {hibernate, NState} -> - hibernate(GS2State #gs2_state { state = NState } ); - Reply -> - handle_common_termination(Reply, pre_hibernate, GS2State) - end; - false -> - hibernate(GS2State) - end. - -post_hibernate(GS2State = #gs2_state { state = State, - mod = Mod }) -> - case erlang:function_exported(Mod, handle_post_hibernate, 1) of - true -> - case catch Mod:handle_post_hibernate(State) of - {noreply, NState} -> - process_next_msg(GS2State #gs2_state { state = NState, - time = infinity }); - {noreply, NState, Time} -> - process_next_msg(GS2State #gs2_state { state = NState, - time = Time }); - Reply -> - handle_common_termination(Reply, post_hibernate, GS2State) - end; - false -> - %% use hibernate here, not infinity. This matches - %% R13B. The key is that we should be able to get through - %% to process_msg calling sys:handle_system_msg with Time - %% still set to hibernate, iff that msg is the very msg - %% that woke us up (or the first msg we receive after - %% waking up). - process_next_msg(GS2State #gs2_state { time = hibernate }) - end. - -adjust_timeout_state(SleptAt, AwokeAt, {backoff, CurrentTO, MinimumTO, - DesiredHibPeriod, RandomState}) -> - NapLengthMicros = timer:now_diff(AwokeAt, SleptAt), - CurrentMicros = CurrentTO * 1000, - MinimumMicros = MinimumTO * 1000, - DesiredHibMicros = DesiredHibPeriod * 1000, - GapBetweenMessagesMicros = NapLengthMicros + CurrentMicros, - Base = - %% If enough time has passed between the last two messages then we - %% should consider sleeping sooner. Otherwise stay awake longer. - case GapBetweenMessagesMicros > (MinimumMicros + DesiredHibMicros) of - true -> lists:max([MinimumTO, CurrentTO div 2]); - false -> CurrentTO - end, - {Extra, RandomState1} = random:uniform_s(Base, RandomState), - CurrentTO1 = Base + Extra, - {backoff, CurrentTO1, MinimumTO, DesiredHibPeriod, RandomState1}. - -in({'$gen_cast', Msg} = Input, - GS2State = #gs2_state { prioritisers = {_, F, _} }) -> - in(Input, F(Msg, GS2State), GS2State); -in({'$gen_call', From, Msg} = Input, - GS2State = #gs2_state { prioritisers = {F, _, _} }) -> - in(Input, F(Msg, From, GS2State), GS2State); -in({'$with_state', _From, _Fun} = Input, GS2State) -> - in(Input, 0, GS2State); -in({'EXIT', Parent, _R} = Input, GS2State = #gs2_state { parent = Parent }) -> - in(Input, infinity, GS2State); -in({system, _From, _Req} = Input, GS2State) -> - in(Input, infinity, GS2State); -in(Input, GS2State = #gs2_state { prioritisers = {_, _, F} }) -> - in(Input, F(Input, GS2State), GS2State). - -in(_Input, drop, GS2State) -> - GS2State; - -in(Input, Priority, GS2State = #gs2_state { queue = Queue }) -> - GS2State # gs2_state { queue = priority_queue:in(Input, Priority, Queue) }. - -process_msg({system, From, Req}, - GS2State = #gs2_state { parent = Parent, debug = Debug }) -> - %% gen_server puts Hib on the end as the 7th arg, but that version - %% of the fun seems not to be documented so leaving out for now. - sys:handle_system_msg(Req, From, Parent, ?MODULE, Debug, GS2State); -process_msg({'$with_state', From, Fun}, - GS2State = #gs2_state{state = State}) -> - reply(From, catch Fun(State)), - loop(GS2State); -process_msg({'EXIT', Parent, Reason} = Msg, - GS2State = #gs2_state { parent = Parent }) -> - terminate(Reason, Msg, GS2State); -process_msg(Msg, GS2State = #gs2_state { debug = [] }) -> - handle_msg(Msg, GS2State); -process_msg(Msg, GS2State = #gs2_state { name = Name, debug = Debug }) -> - Debug1 = sys:handle_debug(Debug, fun print_event/3, Name, {in, Msg}), - handle_msg(Msg, GS2State #gs2_state { debug = Debug1 }). - -%%% --------------------------------------------------- -%%% Send/recive functions -%%% --------------------------------------------------- -do_send(Dest, Msg) -> - catch erlang:send(Dest, Msg). - -do_multi_call(Nodes, Name, Req, infinity) -> - Tag = make_ref(), - Monitors = send_nodes(Nodes, Name, Tag, Req), - rec_nodes(Tag, Monitors, Name, undefined); -do_multi_call(Nodes, Name, Req, Timeout) -> - Tag = make_ref(), - Caller = self(), - Receiver = - spawn( - fun () -> - %% Middleman process. Should be unsensitive to regular - %% exit signals. The sychronization is needed in case - %% the receiver would exit before the caller started - %% the monitor. - process_flag(trap_exit, true), - Mref = erlang:monitor(process, Caller), - receive - {Caller,Tag} -> - Monitors = send_nodes(Nodes, Name, Tag, Req), - TimerId = erlang:start_timer(Timeout, self(), ok), - Result = rec_nodes(Tag, Monitors, Name, TimerId), - exit({self(),Tag,Result}); - {'DOWN',Mref,_,_,_} -> - %% Caller died before sending us the go-ahead. - %% Give up silently. - exit(normal) - end - end), - Mref = erlang:monitor(process, Receiver), - Receiver ! {self(),Tag}, - receive - {'DOWN',Mref,_,_,{Receiver,Tag,Result}} -> - Result; - {'DOWN',Mref,_,_,Reason} -> - %% The middleman code failed. Or someone did - %% exit(_, kill) on the middleman process => Reason==killed - exit(Reason) - end. - -send_nodes(Nodes, Name, Tag, Req) -> - send_nodes(Nodes, Name, Tag, Req, []). - -send_nodes([Node|Tail], Name, Tag, Req, Monitors) - when is_atom(Node) -> - Monitor = start_monitor(Node, Name), - %% Handle non-existing names in rec_nodes. - catch {Name, Node} ! {'$gen_call', {self(), {Tag, Node}}, Req}, - send_nodes(Tail, Name, Tag, Req, [Monitor | Monitors]); -send_nodes([_Node|Tail], Name, Tag, Req, Monitors) -> - %% Skip non-atom Node - send_nodes(Tail, Name, Tag, Req, Monitors); -send_nodes([], _Name, _Tag, _Req, Monitors) -> - Monitors. - -%% Against old nodes: -%% If no reply has been delivered within 2 secs. (per node) check that -%% the server really exists and wait for ever for the answer. -%% -%% Against contemporary nodes: -%% Wait for reply, server 'DOWN', or timeout from TimerId. - -rec_nodes(Tag, Nodes, Name, TimerId) -> - rec_nodes(Tag, Nodes, Name, [], [], 2000, TimerId). - -rec_nodes(Tag, [{N,R}|Tail], Name, Badnodes, Replies, Time, TimerId ) -> - receive - {'DOWN', R, _, _, _} -> - rec_nodes(Tag, Tail, Name, [N|Badnodes], Replies, Time, TimerId); - {{Tag, N}, Reply} -> %% Tag is bound !!! - unmonitor(R), - rec_nodes(Tag, Tail, Name, Badnodes, - [{N,Reply}|Replies], Time, TimerId); - {timeout, TimerId, _} -> - unmonitor(R), - %% Collect all replies that already have arrived - rec_nodes_rest(Tag, Tail, Name, [N|Badnodes], Replies) - end; -rec_nodes(Tag, [N|Tail], Name, Badnodes, Replies, Time, TimerId) -> - %% R6 node - receive - {nodedown, N} -> - monitor_node(N, false), - rec_nodes(Tag, Tail, Name, [N|Badnodes], Replies, 2000, TimerId); - {{Tag, N}, Reply} -> %% Tag is bound !!! - receive {nodedown, N} -> ok after 0 -> ok end, - monitor_node(N, false), - rec_nodes(Tag, Tail, Name, Badnodes, - [{N,Reply}|Replies], 2000, TimerId); - {timeout, TimerId, _} -> - receive {nodedown, N} -> ok after 0 -> ok end, - monitor_node(N, false), - %% Collect all replies that already have arrived - rec_nodes_rest(Tag, Tail, Name, [N | Badnodes], Replies) - after Time -> - case rpc:call(N, erlang, whereis, [Name]) of - Pid when is_pid(Pid) -> % It exists try again. - rec_nodes(Tag, [N|Tail], Name, Badnodes, - Replies, infinity, TimerId); - _ -> % badnode - receive {nodedown, N} -> ok after 0 -> ok end, - monitor_node(N, false), - rec_nodes(Tag, Tail, Name, [N|Badnodes], - Replies, 2000, TimerId) - end - end; -rec_nodes(_, [], _, Badnodes, Replies, _, TimerId) -> - case catch erlang:cancel_timer(TimerId) of - false -> % It has already sent it's message - receive - {timeout, TimerId, _} -> ok - after 0 -> - ok - end; - _ -> % Timer was cancelled, or TimerId was 'undefined' - ok - end, - {Replies, Badnodes}. - -%% Collect all replies that already have arrived -rec_nodes_rest(Tag, [{N,R}|Tail], Name, Badnodes, Replies) -> - receive - {'DOWN', R, _, _, _} -> - rec_nodes_rest(Tag, Tail, Name, [N|Badnodes], Replies); - {{Tag, N}, Reply} -> %% Tag is bound !!! - unmonitor(R), - rec_nodes_rest(Tag, Tail, Name, Badnodes, [{N,Reply}|Replies]) - after 0 -> - unmonitor(R), - rec_nodes_rest(Tag, Tail, Name, [N|Badnodes], Replies) - end; -rec_nodes_rest(Tag, [N|Tail], Name, Badnodes, Replies) -> - %% R6 node - receive - {nodedown, N} -> - monitor_node(N, false), - rec_nodes_rest(Tag, Tail, Name, [N|Badnodes], Replies); - {{Tag, N}, Reply} -> %% Tag is bound !!! - receive {nodedown, N} -> ok after 0 -> ok end, - monitor_node(N, false), - rec_nodes_rest(Tag, Tail, Name, Badnodes, [{N,Reply}|Replies]) - after 0 -> - receive {nodedown, N} -> ok after 0 -> ok end, - monitor_node(N, false), - rec_nodes_rest(Tag, Tail, Name, [N|Badnodes], Replies) - end; -rec_nodes_rest(_Tag, [], _Name, Badnodes, Replies) -> - {Replies, Badnodes}. - - -%%% --------------------------------------------------- -%%% Monitor functions -%%% --------------------------------------------------- - -start_monitor(Node, Name) when is_atom(Node), is_atom(Name) -> - if node() =:= nonode@nohost, Node =/= nonode@nohost -> - Ref = make_ref(), - self() ! {'DOWN', Ref, process, {Name, Node}, noconnection}, - {Node, Ref}; - true -> - case catch erlang:monitor(process, {Name, Node}) of - {'EXIT', _} -> - %% Remote node is R6 - monitor_node(Node, true), - Node; - Ref when is_reference(Ref) -> - {Node, Ref} - end - end. - -%% Cancels a monitor started with Ref=erlang:monitor(_, _). -unmonitor(Ref) when is_reference(Ref) -> - erlang:demonitor(Ref), - receive - {'DOWN', Ref, _, _, _} -> - true - after 0 -> - true - end. - -%%% --------------------------------------------------- -%%% Message handling functions -%%% --------------------------------------------------- - -dispatch({'$gen_cast', Msg}, Mod, State) -> - Mod:handle_cast(Msg, State); -dispatch(Info, Mod, State) -> - Mod:handle_info(Info, State). - -common_reply(_Name, From, Reply, _NState, [] = _Debug) -> - reply(From, Reply), - []; -common_reply(Name, {To, _Tag} = From, Reply, NState, Debug) -> - reply(From, Reply), - sys:handle_debug(Debug, fun print_event/3, Name, {out, Reply, To, NState}). - -common_noreply(_Name, _NState, [] = _Debug) -> - []; -common_noreply(Name, NState, Debug) -> - sys:handle_debug(Debug, fun print_event/3, Name, {noreply, NState}). - -common_become(_Name, _Mod, _NState, [] = _Debug) -> - []; -common_become(Name, Mod, NState, Debug) -> - sys:handle_debug(Debug, fun print_event/3, Name, {become, Mod, NState}). - -handle_msg({'$gen_call', From, Msg}, GS2State = #gs2_state { mod = Mod, - state = State, - name = Name, - debug = Debug }) -> - case catch Mod:handle_call(Msg, From, State) of - {reply, Reply, NState} -> - Debug1 = common_reply(Name, From, Reply, NState, Debug), - loop(GS2State #gs2_state { state = NState, - time = infinity, - debug = Debug1 }); - {reply, Reply, NState, Time1} -> - Debug1 = common_reply(Name, From, Reply, NState, Debug), - loop(GS2State #gs2_state { state = NState, - time = Time1, - debug = Debug1}); - {stop, Reason, Reply, NState} -> - {'EXIT', R} = - (catch terminate(Reason, Msg, - GS2State #gs2_state { state = NState })), - common_reply(Name, From, Reply, NState, Debug), - exit(R); - Other -> - handle_common_reply(Other, Msg, GS2State) - end; -handle_msg(Msg, GS2State = #gs2_state { mod = Mod, state = State }) -> - Reply = (catch dispatch(Msg, Mod, State)), - handle_common_reply(Reply, Msg, GS2State). - -handle_common_reply(Reply, Msg, GS2State = #gs2_state { name = Name, - debug = Debug}) -> - case Reply of - {noreply, NState} -> - Debug1 = common_noreply(Name, NState, Debug), - loop(GS2State #gs2_state {state = NState, - time = infinity, - debug = Debug1}); - {noreply, NState, Time1} -> - Debug1 = common_noreply(Name, NState, Debug), - loop(GS2State #gs2_state {state = NState, - time = Time1, - debug = Debug1}); - {become, Mod, NState} -> - Debug1 = common_become(Name, Mod, NState, Debug), - loop(find_prioritisers( - GS2State #gs2_state { mod = Mod, - state = NState, - time = infinity, - debug = Debug1 })); - {become, Mod, NState, Time1} -> - Debug1 = common_become(Name, Mod, NState, Debug), - loop(find_prioritisers( - GS2State #gs2_state { mod = Mod, - state = NState, - time = Time1, - debug = Debug1 })); - _ -> - handle_common_termination(Reply, Msg, GS2State) - end. - -handle_common_termination(Reply, Msg, GS2State) -> - case Reply of - {stop, Reason, NState} -> - terminate(Reason, Msg, GS2State #gs2_state { state = NState }); - {'EXIT', What} -> - terminate(What, Msg, GS2State); - _ -> - terminate({bad_return_value, Reply}, Msg, GS2State) - end. - -%%----------------------------------------------------------------- -%% Callback functions for system messages handling. -%%----------------------------------------------------------------- -system_continue(Parent, Debug, GS2State) -> - loop(GS2State #gs2_state { parent = Parent, debug = Debug }). - -system_terminate(Reason, _Parent, Debug, GS2State) -> - terminate(Reason, [], GS2State #gs2_state { debug = Debug }). - -system_code_change(GS2State = #gs2_state { mod = Mod, - state = State }, - _Module, OldVsn, Extra) -> - case catch Mod:code_change(OldVsn, State, Extra) of - {ok, NewState} -> - NewGS2State = find_prioritisers( - GS2State #gs2_state { state = NewState }), - {ok, [NewGS2State]}; - Else -> - Else - end. - -%%----------------------------------------------------------------- -%% Format debug messages. Print them as the call-back module sees -%% them, not as the real erlang messages. Use trace for that. -%%----------------------------------------------------------------- -print_event(Dev, {in, Msg}, Name) -> - case Msg of - {'$gen_call', {From, _Tag}, Call} -> - io:format(Dev, "*DBG* ~p got call ~p from ~w~n", - [Name, Call, From]); - {'$gen_cast', Cast} -> - io:format(Dev, "*DBG* ~p got cast ~p~n", - [Name, Cast]); - _ -> - io:format(Dev, "*DBG* ~p got ~p~n", [Name, Msg]) - end; -print_event(Dev, {out, Msg, To, State}, Name) -> - io:format(Dev, "*DBG* ~p sent ~p to ~w, new state ~w~n", - [Name, Msg, To, State]); -print_event(Dev, {noreply, State}, Name) -> - io:format(Dev, "*DBG* ~p new state ~w~n", [Name, State]); -print_event(Dev, Event, Name) -> - io:format(Dev, "*DBG* ~p dbg ~p~n", [Name, Event]). - - -%%% --------------------------------------------------- -%%% Terminate the server. -%%% --------------------------------------------------- - -terminate(Reason, Msg, #gs2_state { name = Name, - mod = Mod, - state = State, - debug = Debug }) -> - case catch Mod:terminate(Reason, State) of - {'EXIT', R} -> - error_info(R, Reason, Name, Msg, State, Debug), - exit(R); - _ -> - case Reason of - normal -> - exit(normal); - shutdown -> - exit(shutdown); - {shutdown,_}=Shutdown -> - exit(Shutdown); - _ -> - error_info(Reason, undefined, Name, Msg, State, Debug), - exit(Reason) - end - end. - -error_info(_Reason, _RootCause, application_controller, _Msg, _State, _Debug) -> - %% OTP-5811 Don't send an error report if it's the system process - %% application_controller which is terminating - let init take care - %% of it instead - ok; -error_info(Reason, RootCause, Name, Msg, State, Debug) -> - Reason1 = error_reason(Reason), - Fmt = - "** Generic server ~p terminating~n" - "** Last message in was ~p~n" - "** When Server state == ~p~n" - "** Reason for termination == ~n** ~p~n", - case RootCause of - undefined -> format(Fmt, [Name, Msg, State, Reason1]); - _ -> format(Fmt ++ "** In 'terminate' callback " - "with reason ==~n** ~p~n", - [Name, Msg, State, Reason1, - error_reason(RootCause)]) - end, - sys:print_log(Debug), - ok. - -error_reason({undef,[{M,F,A}|MFAs]} = Reason) -> - case code:is_loaded(M) of - false -> {'module could not be loaded',[{M,F,A}|MFAs]}; - _ -> case erlang:function_exported(M, F, length(A)) of - true -> Reason; - false -> {'function not exported',[{M,F,A}|MFAs]} - end - end; -error_reason(Reason) -> - Reason. - -%%% --------------------------------------------------- -%%% Misc. functions. -%%% --------------------------------------------------- - -opt(Op, [{Op, Value}|_]) -> - {ok, Value}; -opt(Op, [_|Options]) -> - opt(Op, Options); -opt(_, []) -> - false. - -debug_options(Name, Opts) -> - case opt(debug, Opts) of - {ok, Options} -> dbg_options(Name, Options); - _ -> dbg_options(Name, []) - end. - -dbg_options(Name, []) -> - Opts = - case init:get_argument(generic_debug) of - error -> - []; - _ -> - [log, statistics] - end, - dbg_opts(Name, Opts); -dbg_options(Name, Opts) -> - dbg_opts(Name, Opts). - -dbg_opts(Name, Opts) -> - case catch sys:debug_options(Opts) of - {'EXIT',_} -> - format("~p: ignoring erroneous debug options - ~p~n", - [Name, Opts]), - []; - Dbg -> - Dbg - end. - -get_proc_name(Pid) when is_pid(Pid) -> - Pid; -get_proc_name({local, Name}) -> - case process_info(self(), registered_name) of - {registered_name, Name} -> - Name; - {registered_name, _Name} -> - exit(process_not_registered); - [] -> - exit(process_not_registered) - end; -get_proc_name({global, Name}) -> - case whereis_name(Name) of - undefined -> - exit(process_not_registered_globally); - Pid when Pid =:= self() -> - Name; - _Pid -> - exit(process_not_registered_globally) - end. - -get_parent() -> - case get('$ancestors') of - [Parent | _] when is_pid(Parent)-> - Parent; - [Parent | _] when is_atom(Parent)-> - name_to_pid(Parent); - _ -> - exit(process_was_not_started_by_proc_lib) - end. - -name_to_pid(Name) -> - case whereis(Name) of - undefined -> - case whereis_name(Name) of - undefined -> - exit(could_not_find_registerd_name); - Pid -> - Pid - end; - Pid -> - Pid - end. - -whereis_name(Name) -> - case ets:lookup(global_names, Name) of - [{_Name, Pid, _Method, _RPid, _Ref}] -> - if node(Pid) == node() -> - case is_process_alive(Pid) of - true -> Pid; - false -> undefined - end; - true -> - Pid - end; - [] -> undefined - end. - -find_prioritisers(GS2State = #gs2_state { mod = Mod }) -> - PCall = function_exported_or_default(Mod, 'prioritise_call', 4, - fun (_Msg, _From, _State) -> 0 end), - PCast = function_exported_or_default(Mod, 'prioritise_cast', 3, - fun (_Msg, _State) -> 0 end), - PInfo = function_exported_or_default(Mod, 'prioritise_info', 3, - fun (_Msg, _State) -> 0 end), - GS2State #gs2_state { prioritisers = {PCall, PCast, PInfo} }. - -function_exported_or_default(Mod, Fun, Arity, Default) -> - case erlang:function_exported(Mod, Fun, Arity) of - true -> case Arity of - 3 -> fun (Msg, GS2State = #gs2_state { queue = Queue, - state = State }) -> - Length = priority_queue:len(Queue), - case catch Mod:Fun(Msg, Length, State) of - drop -> - drop; - Res when is_integer(Res) -> - Res; - Err -> - handle_common_termination(Err, Msg, GS2State) - end - end; - 4 -> fun (Msg, From, GS2State = #gs2_state { queue = Queue, - state = State }) -> - Length = priority_queue:len(Queue), - case catch Mod:Fun(Msg, From, Length, State) of - Res when is_integer(Res) -> - Res; - Err -> - handle_common_termination(Err, Msg, GS2State) - end - end - end; - false -> Default - end. - -%%----------------------------------------------------------------- -%% Status information -%%----------------------------------------------------------------- -format_status(Opt, StatusData) -> - [PDict, SysState, Parent, Debug, - #gs2_state{name = Name, state = State, mod = Mod, queue = Queue}] = - StatusData, - NameTag = if is_pid(Name) -> - pid_to_list(Name); - is_atom(Name) -> - Name - end, - Header = lists:concat(["Status for generic server ", NameTag]), - Log = sys:get_debug(log, Debug, []), - Specfic = callback(Mod, format_status, [Opt, [PDict, State]], - fun () -> [{data, [{"State", State}]}] end), - Messages = callback(Mod, format_message_queue, [Opt, Queue], - fun () -> priority_queue:to_list(Queue) end), - [{header, Header}, - {data, [{"Status", SysState}, - {"Parent", Parent}, - {"Logged events", Log}, - {"Queued messages", Messages}]} | - Specfic]. - -callback(Mod, FunName, Args, DefaultThunk) -> - case erlang:function_exported(Mod, FunName, length(Args)) of - true -> case catch apply(Mod, FunName, Args) of - {'EXIT', _} -> DefaultThunk(); - Success -> Success - end; - false -> DefaultThunk() - end. |