libdb/test/java/rep/fiddler/registry.erl
2011-09-13 13:44:24 -04:00

89 lines
2.6 KiB
Erlang

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