diff options
Diffstat (limited to 'deps/rabbit_common/src/gen_server2.erl')
| -rw-r--r-- | deps/rabbit_common/src/gen_server2.erl | 1419 |
1 files changed, 1419 insertions, 0 deletions
diff --git a/deps/rabbit_common/src/gen_server2.erl b/deps/rabbit_common/src/gen_server2.erl new file mode 100644 index 0000000000..b80e921a89 --- /dev/null +++ b/deps/rabbit_common/src/gen_server2.erl @@ -0,0 +1,1419 @@ +%% 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. +%% +%% 11) Internal buffer length is emitted as a core [RabbitMQ] metric. + +%% All modifications are (C) 2009-2020 VMware, Inc. or its affiliates. + +%% ``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 https://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). + +-ifdef(OTP_RELEASE). +-if(?OTP_RELEASE >= 22). +-compile(nowarn_deprecated_function). +-endif. +-endif. + +%%% --------------------------------------------------- +%%% +%%% 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, + stop/1, stop/3, + 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, + timer, emit_stats_fun, stop_stats_fun}). + +%%%========================================================================= +%%% Specs. These exist only to shut up dialyzer's warnings +%%%========================================================================= + +-type gs2_state() :: #gs2_state{}. + +-spec handle_common_termination(any(), atom(), gs2_state()) -> no_return(). +-spec hibernate(gs2_state()) -> no_return(). +-spec pre_hibernate(gs2_state()) -> no_return(). +-spec system_terminate(_, _, _, gs2_state()) -> no_return(). + +-type millis() :: non_neg_integer(). + +-dialyzer({nowarn_function, do_multi_call/4}). + +%%%========================================================================= +%%% 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). + +%%% ----------------------------------------------------------------- +%%% 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). + +%% ----------------------------------------------------------------- +%% Stop a generic server and wait for it to terminate. +%% If the server is located at another node, that node will +%% be monitored. +%% ----------------------------------------------------------------- +stop(Name) -> + gen:stop(Name). + +stop(Name, Reason, Timeout) -> + gen:stop(Name, Reason, Timeout). + +%% ----------------------------------------------------------------- +%% 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, {'$gen_cast', Request}), + ok; +cast({Name,Node}=Dest, Request) when is_atom(Name), is_atom(Node) -> + catch (Dest ! {'$gen_cast', Request}), + ok; +cast(Dest, Request) when is_atom(Dest); is_pid(Dest) -> + catch (Dest ! {'$gen_cast', Request}), + ok. + +%% ----------------------------------------------------------------- +%% Send a reply to the client. +%% ----------------------------------------------------------------- +reply({To, Tag}, Reply) -> + catch To ! {Tag, Reply}. + +%% ----------------------------------------------------------------- +%% Asynchronous broadcast, returns nothing, it's just send'n pray +%% ----------------------------------------------------------------- +abcast(Name, Request) when is_atom(Name) -> + do_abcast([node() | nodes()], Name, {'$gen_cast', Request}). + +abcast(Nodes, Name, Request) when is_list(Nodes), is_atom(Name) -> + do_abcast(Nodes, Name, {'$gen_cast', Request}). + +do_abcast([Node|Nodes], Name, Msg) when is_atom(Node) -> + catch ({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), + {EmitStatsFun, StopStatsFun} = stats_funs(), + loop(init_stats(find_prioritisers( + #gs2_state { parent = Parent, name = Name, state = State, + mod = Mod, time = Timeout, timeout_state = Backoff1, + queue = Queue, debug = Debug, + emit_stats_fun = EmitStatsFun, + stop_stats_fun = StopStatsFun }))). + +%%%======================================================================== +%%% 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(), + {EmitStatsFun, StopStatsFun} = stats_funs(), + GS2State = find_prioritisers( + #gs2_state { parent = Parent, + name = Name, + mod = Mod, + queue = Queue, + debug = Debug, + emit_stats_fun = EmitStatsFun, + stop_stats_fun = StopStatsFun }), + case catch Mod:init(Args) of + {ok, State} -> + proc_lib:init_ack(Starter, {ok, self()}), + loop(init_stats(GS2State#gs2_state { state = State, + time = infinity, + timeout_state = undefined })); + {ok, State, Timeout} -> + proc_lib:init_ack(Starter, {ok, self()}), + loop(init_stats( + 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(init_stats(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(init_stats(find_prioritisers( + 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, + rand:seed(exsplus)}. + +%%%======================================================================== +%%% Internal functions +%%%======================================================================== +%%% --------------------------------------------------- +%%% The MAIN loop. +%%% --------------------------------------------------- +loop(GS2State = #gs2_state { time = hibernate, + timeout_state = undefined, + queue = Queue }) -> + case priority_queue:is_empty(Queue) of + true -> + pre_hibernate(GS2State); + false -> + process_next_msg(GS2State) + end; + +loop(GS2State) -> + process_next_msg(drain(GS2State)). + +drain(GS2State) -> + receive + Input -> drain(in(Input, GS2State)) + after 0 -> GS2State + end. + +process_next_msg(GS2State0 = #gs2_state { time = Time, + timeout_state = TimeoutState, + queue = Queue }) -> + case priority_queue:out(Queue) of + {{value, Msg}, Queue1} -> + GS2State = ensure_stats_timer(GS2State0), + process_msg(Msg, GS2State#gs2_state { queue = Queue1 }); + {empty, Queue1} -> + {Time1, HibOnTimeout, GS2State} + = case {Time, TimeoutState} of + {hibernate, {backoff, Current, _Min, _Desired, _RSt}} -> + {Current, true, stop_stats_timer(GS2State0)}; + {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, GS2State0}; + _ -> {Time, false, GS2State0} + 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, + erlang:monotonic_time(), + 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, _, _, _, _} -> {erlang:monotonic_time(), + TimeoutState} + end, + proc_lib:hibernate(?MODULE, wake_hib, + [GS2State #gs2_state { timeout_state = TS }]). + +pre_hibernate(GS2State0 = #gs2_state { state = State, + mod = Mod, + emit_stats_fun = EmitStatsFun }) -> + GS2State = EmitStatsFun(stop_stats_timer(GS2State0)), + 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(GS2State0 = #gs2_state { state = State, + mod = Mod }) -> + GS2State = ensure_stats_timer(GS2State0), + 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 = erlang:convert_time_unit(AwokeAt - SleptAt, + native, micro_seconds), + 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} = rand: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(emit_gen_server2_stats, GS2State = #gs2_state{ emit_stats_fun = EmitStatsFun}) -> + next_stats_timer(EmitStatsFun(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 }) -> + case Req of + %% This clause will match only in R16B03. + %% Since 17.0 replace_state is not a system message. + {replace_state, StateFun} -> + GS2State1 = StateFun(GS2State), + _ = gen:reply(From, GS2State1), + system_continue(Parent, Debug, GS2State1); + _ -> + %% 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) + end; +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_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 synchronization 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. +%%% --------------------------------------------------- + +-spec terminate(_, _, _) -> no_return(). + +terminate(Reason, Msg, #gs2_state { name = Name, + mod = Mod, + state = State, + debug = Debug, + stop_stats_fun = StopStatsFun + } = GS2State) -> + StopStatsFun(stop_stats_timer(GS2State)), + 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_registered_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. + +stats_funs() -> + case ets:info(gen_server2_metrics) of + undefined -> + {fun(GS2State) -> GS2State end, + fun(GS2State) -> GS2State end}; + _ -> + {fun emit_stats/1, fun stop_stats/1} + end. + +init_stats(State = #gs2_state{ emit_stats_fun = EmitStatsFun }) -> + StateWithInitTimer = rabbit_event:init_stats_timer(State, #gs2_state.timer), + next_stats_timer(EmitStatsFun(StateWithInitTimer)). + +next_stats_timer(State) -> + ensure_stats_timer(rabbit_event:reset_stats_timer(State, #gs2_state.timer)). + +ensure_stats_timer(State) -> + rabbit_event:ensure_stats_timer(State, + #gs2_state.timer, + emit_gen_server2_stats). + +stop_stats_timer(State) -> + rabbit_event:stop_stats_timer(State, #gs2_state.timer). + +emit_stats(State = #gs2_state{queue = Queue}) -> + rabbit_core_metrics:gen_server2_stats(self(), priority_queue:len(Queue)), + State. + +stop_stats(State) -> + rabbit_core_metrics:gen_server2_deleted(self()), + State. |