diff options
Diffstat (limited to 'src/gatherer.erl')
| -rw-r--r-- | src/gatherer.erl | 145 |
1 files changed, 145 insertions, 0 deletions
diff --git a/src/gatherer.erl b/src/gatherer.erl new file mode 100644 index 00000000..31dda16e --- /dev/null +++ b/src/gatherer.erl @@ -0,0 +1,145 @@ +%% The contents of this file are subject to the Mozilla Public License +%% Version 1.1 (the "License"); you may not use this file except in +%% compliance with the License. You may obtain a copy of the License at +%% http://www.mozilla.org/MPL/ +%% +%% 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 Original Code is RabbitMQ. +%% +%% The Initial Developers of the Original Code are LShift Ltd, +%% Cohesive Financial Technologies LLC, and Rabbit Technologies Ltd. +%% +%% Portions created before 22-Nov-2008 00:00:00 GMT by LShift Ltd, +%% Cohesive Financial Technologies LLC, or Rabbit Technologies Ltd +%% are Copyright (C) 2007-2008 LShift Ltd, Cohesive Financial +%% Technologies LLC, and Rabbit Technologies Ltd. +%% +%% Portions created by LShift Ltd are Copyright (C) 2007-2010 LShift +%% Ltd. Portions created by Cohesive Financial Technologies LLC are +%% Copyright (C) 2007-2010 Cohesive Financial Technologies +%% LLC. Portions created by Rabbit Technologies Ltd are Copyright +%% (C) 2007-2010 Rabbit Technologies Ltd. +%% +%% All Rights Reserved. +%% +%% Contributor(s): ______________________________________. +%% + +-module(gatherer). + +-behaviour(gen_server2). + +-export([start_link/0, stop/1, fork/1, finish/1, in/2, out/1]). + +-export([init/1, handle_call/3, handle_cast/2, handle_info/2, + terminate/2, code_change/3]). + +%%---------------------------------------------------------------------------- + +-ifdef(use_specs). + +-spec(start_link/0 :: () -> {'ok', pid()} | 'ignore' | {'error', any()}). +-spec(stop/1 :: (pid()) -> 'ok'). +-spec(fork/1 :: (pid()) -> 'ok'). +-spec(finish/1 :: (pid()) -> 'ok'). +-spec(in/2 :: (pid(), any()) -> 'ok'). +-spec(out/1 :: (pid()) -> {'value', any()} | 'empty'). + +-endif. + +%%---------------------------------------------------------------------------- + +-define(HIBERNATE_AFTER_MIN, 1000). +-define(DESIRED_HIBERNATE, 10000). + +%%---------------------------------------------------------------------------- + +-record(gstate, { forks, values, blocked }). + +%%---------------------------------------------------------------------------- + +start_link() -> + gen_server2:start_link(?MODULE, [], [{timeout, infinity}]). + +stop(Pid) -> + gen_server2:call(Pid, stop, infinity). + +fork(Pid) -> + gen_server2:call(Pid, fork, infinity). + +finish(Pid) -> + gen_server2:cast(Pid, finish). + +in(Pid, Value) -> + gen_server2:cast(Pid, {in, Value}). + +out(Pid) -> + gen_server2:call(Pid, out, infinity). + +%%---------------------------------------------------------------------------- + +init([]) -> + {ok, #gstate { forks = 0, values = queue:new(), blocked = queue:new() }, + hibernate, + {backoff, ?HIBERNATE_AFTER_MIN, ?HIBERNATE_AFTER_MIN, ?DESIRED_HIBERNATE}}. + +handle_call(stop, _From, State) -> + {stop, normal, ok, State}; + +handle_call(fork, _From, State = #gstate { forks = Forks }) -> + {reply, ok, State #gstate { forks = Forks + 1 }, hibernate}; + +handle_call(out, From, State = #gstate { forks = Forks, + values = Values, + blocked = Blocked }) -> + case queue:out(Values) of + {empty, _} -> + case Forks of + 0 -> {reply, empty, State, hibernate}; + _ -> {noreply, + State #gstate { blocked = queue:in(From, Blocked) }, + hibernate} + end; + {{value, _Value} = V, NewValues} -> + {reply, V, State #gstate { values = NewValues }, hibernate} + end; + +handle_call(Msg, _From, State) -> + {stop, {unexpected_call, Msg}, State}. + +handle_cast(finish, State = #gstate { forks = Forks, blocked = Blocked }) -> + NewForks = Forks - 1, + NewBlocked = case NewForks of + 0 -> [gen_server2:reply(From, empty) || + From <- queue:to_list(Blocked)], + queue:new(); + _ -> Blocked + end, + {noreply, State #gstate { forks = NewForks, blocked = NewBlocked }, + hibernate}; + +handle_cast({in, Value}, State = #gstate { values = Values, + blocked = Blocked }) -> + {noreply, case queue:out(Blocked) of + {empty, _} -> + State #gstate { values = queue:in(Value, Values) }; + {{value, From}, NewBlocked} -> + gen_server2:reply(From, {value, Value}), + State #gstate { blocked = NewBlocked } + end, hibernate}; + +handle_cast(Msg, State) -> + {stop, {unexpected_cast, Msg}, State}. + +handle_info(Msg, State) -> + {stop, {unexpected_info, Msg}, State}. + +code_change(_OldVsn, State, _Extra) -> + {ok, State}. + +terminate(_Reason, State) -> + State. |