%% Copyright (c) 2013, Pedram Nimreezi <deadzen@deadzen.com>
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%%
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%% Permission to use, copy, modify, and/or distribute this software for any
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%% purpose with or without fee is hereby granted, provided that the above
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%% copyright notice and this permission notice appear in all copies.
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%%
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%% THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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%% WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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%% MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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%% ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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%% WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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%% ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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%% OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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%% @doc Process table manager for goldrush.
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%%
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%% Manager responsible for the processes, which serve as heir of the
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%% {@link gr_counter:start_link/0. <em>Counter</em>} and
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%% {@link gr_param:start_link/0. <em>Param</em>} ets table processes.
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%% This process creates the table and initial data then assigns itself
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%% to inherit the ets table if any process responsible for it is killed.
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%% It then waits to give it back while that process is recreated by its
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%% supervisor.
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-module(gr_manager).
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-behaviour(gen_server).
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%% API
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-export([start_link/3, wait_for_pid/1]).
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%% gen_server callbacks
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-export([init/1,
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handle_call/3,
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handle_cast/2,
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handle_info/2,
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terminate/2,
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code_change/3]).
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-define(SERVER, ?MODULE).
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-record(state, {table_id :: ets:tab(), managee :: atom()}).
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%%%===================================================================
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%%% API
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%%%===================================================================
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%% Setup the initial data for the ets table
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-spec setup(atom() | pid(), term()) -> ok.
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setup(Name, Data) ->
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gen_server:cast(Name, {setup, Data}).
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%%--------------------------------------------------------------------
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%% @doc
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%% Starts the server
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%%
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%% @spec start_link(Name, Managee, Data) -> {ok, Pid} | ignore |
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%% {error, Error}
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%% @end
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%%--------------------------------------------------------------------
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start_link(Name, Managee, Data) ->
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gen_server:start_link({local, Name}, ?MODULE, [Managee, Data], []).
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%%%===================================================================
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%%% gen_server callbacks
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%%%===================================================================
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%%--------------------------------------------------------------------
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%% @private
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%% @doc
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%% Initializes the server
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%%
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%% @spec init(Args) -> {ok, State} |
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%% {ok, State, Timeout} |
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%% ignore |
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%% {stop, Reason}
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%% @end
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%%--------------------------------------------------------------------
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init([Managee, Data]) ->
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process_flag(trap_exit, true),
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setup(self(), Data),
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{ok, #state{managee=Managee}}.
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%%--------------------------------------------------------------------
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%% @private
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%% @doc
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%% Handling call messages
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%%
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%% @spec handle_call(Request, From, State) ->
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%% {reply, Reply, State} |
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%% {reply, Reply, State, Timeout} |
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%% {noreply, State} |
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%% {noreply, State, Timeout} |
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%% {stop, Reason, Reply, State} |
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%% {stop, Reason, State}
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%% @end
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%%--------------------------------------------------------------------
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handle_call(_Request, _From, State) ->
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Reply = {error, unhandled_message},
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{reply, Reply, State}.
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%%--------------------------------------------------------------------
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%% @private
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%% @doc
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%% Handling cast messages
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%%
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%% @spec handle_cast(Msg, State) -> {noreply, State} |
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%% {noreply, State, Timeout} |
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%% {stop, Reason, State}
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%% @end
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%%--------------------------------------------------------------------
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handle_cast({setup, Data}, State = #state{managee=Managee}) ->
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ManageePid = whereis(Managee),
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link(ManageePid),
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TableId = ets:new(?MODULE, [set, private]),
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ets:insert(TableId, Data),
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ets:setopts(TableId, {heir, self(), Data}),
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ets:give_away(TableId, ManageePid, Data),
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{noreply, State#state{table_id=TableId}};
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handle_cast(_Msg, State) ->
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{noreply, State}.
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%%--------------------------------------------------------------------
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%% @private
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%% @doc
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%% Handling all non call/cast messages
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%%
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%% @spec handle_info(Info, State) -> {noreply, State} |
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%% {noreply, State, Timeout} |
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%% {stop, Reason, State}
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%% @end
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%%--------------------------------------------------------------------
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handle_info({'EXIT', _Pid, _Reason}, State) ->
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{noreply, State};
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handle_info({'ETS-TRANSFER', TableId, _Pid, Data}, State = #state{managee=Managee}) ->
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ManageePid = wait_for_pid(Managee),
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link(ManageePid),
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ets:give_away(TableId, ManageePid, Data),
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{noreply, State#state{table_id=TableId}}.
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%% @doc Wait for a registered process to be associated to a process identifier.
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%% @spec wait_for_pid(Managee) -> ManageePid
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-spec wait_for_pid(atom()) -> pid().
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wait_for_pid(Managee) when is_pid(Managee) ->
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Managee;
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wait_for_pid(Managee) when is_atom(Managee), Managee =/= undefined ->
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case whereis(Managee) of
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undefined ->
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timer:sleep(1),
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wait_for_pid(Managee);
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ManageePid -> ManageePid
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end.
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%%--------------------------------------------------------------------
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%% @private
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%% @doc
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%% This function is called by a gen_server when it is about to
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%% terminate. It should be the opposite of Module:init/1 and do any
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%% necessary cleaning up. When it returns, the gen_server terminates
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%% with Reason. The return value is ignored.
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%%
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%% @spec terminate(Reason, State) -> void()
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%% @end
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%%--------------------------------------------------------------------
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terminate(_Reason, _State) ->
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ok.
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%%--------------------------------------------------------------------
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%% @private
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%% @doc
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%% Convert process state when code is changed
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%%
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%% @spec code_change(OldVsn, State, Extra) -> {ok, NewState}
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%% @end
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%%--------------------------------------------------------------------
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code_change(_OldVsn, State, _Extra) ->
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{ok, State}.
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%%%===================================================================
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%%% Internal functions
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%%%===================================================================
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