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90 lines
2.6 KiB
Erlang
90 lines
2.6 KiB
Erlang
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%%% The Registry is a gen_server process that keeps track of the
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%%% currently active set of connection-path processes. The listeners
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%%% add the processes to the list as they're created. The manager
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%%% looks stuff up in order to send commands to the proper place.
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%%%
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%%% For each path we know the two sockets involved, and the
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%%% process(es) reading from them.
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%%%
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%%% A munger looks like either a simple atom (if the rule applies to
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%%% any and all connections paths), or an atom tagged with a path ID
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%%% (like {{6001,6000},page_clog}), which means the rule only applies
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%%% to that path.
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%%%
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%%% Note that "Count" is a count of the number of paths we've *ever*
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%%% registered, not the current length of the list. (Otherwise I
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%%% would have simply called lists:length/1 when needed.)
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-module(registry).
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-behaviour(gen_server).
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-export([start/0,lookup/1,register/4,unregister/1,all/0]).
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-export([init/1, handle_call/3]).
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-export([code_change/3,handle_cast/2,handle_info/2,terminate/2]).
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start() ->
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{ok,_Pid} = gen_server:start({local,registry}, registry, [], []),
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ok.
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init(_) ->
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{ok,{[],0}}.
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%%% TODO: see manager.erl - I think we should get rid of sock and fwd
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%%% from here.
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handle_call({register,Path,Sock,Fwd, Pid}, _From, State) ->
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{Paths,Count} = State,
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{reply, ok, {[{Count,Path,Sock,Fwd,Pid}|Paths],Count+1}};
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handle_call({lookup,Query}, _, State) ->
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{Paths,_Count} = State,
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Index = if
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is_tuple(Query) ->
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2; % Path desc, like {6001,6000}
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true ->
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1 % unique serial ID number
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end,
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case lists:keysearch(Query, Index, Paths) of
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{value, Tpl} ->
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{reply, {ok,Tpl}, State};
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false ->
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{reply, notfound, State}
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end;
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handle_call({unregister,Path}, _, State) ->
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{Paths,Count} = State,
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{reply, ok, {lists:keydelete(Path, 2, Paths),Count}};
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handle_call(all, _, State) ->
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{Paths,_Count} = State,
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{reply, Paths, State}.
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lookup(Query) ->
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gen_server:call(registry, {lookup, Query}).
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register(Path, Sock, Fwd, Pid) ->
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gen_server:call(registry, {register, Path, Sock, Fwd, Pid}).
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unregister(Path) ->
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gen_server:call(registry, {unregister, Path}).
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all() ->
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gen_server:call(registry, all).
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%%%
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%%% The following functions defined in the gen_server behavior are not
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%%% used. But we include them in order to avoid distracting
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%%% compilation warnings.
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%%%
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code_change(_,_,_) ->
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ok.
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handle_cast(_,_) ->
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ok.
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handle_info(_,_) ->
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ok.
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terminate(_,_) ->
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ok.
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