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|
-module(shr_timed_cache).
-behavior(gen_server).
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% TYPES %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% EXPORTS %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%% 'gen_server' Exports
-export
(
[
init/1,
handle_cast/2,
handle_call/3, %% No reply will ever be given.
terminate/2,
code_change/3,
format_status/2,
handle_info/2
]
).
%%%% Actual Interface
-export
(
[
fetch/3,
update/4,
invalidate/3
]
).
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% LOCAL FUNCTIONS %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-spec add_to_cache (atom(), any(), any()) -> any().
add_to_cache (DB, Owner, ObjectID) ->
{ok, TimerPID} = gen_server:start(?MODULE, {DB, {Owner, ObjectID}}, []),
{ok, Data} = shr_database:fetch(DB, ObjectID, Owner),
ets:insert(DB, {{Owner, ObjectID}, TimerPID, Data}),
Data.
-spec add_update_to_cache (atom(), any(), any(), any()) -> 'ok'.
add_update_to_cache (DB, Owner, ObjectID, Data) ->
{ok, TimerPID} = gen_server:start(?MODULE, {DB, {Owner, ObjectID}}, []),
ets:insert(DB, {{Owner, ObjectID}, TimerPID, Data}),
ok.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% EXPORTED FUNCTIONS %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%% 'gen_server' functions
init ({DB, ObjectID}) ->
io:format("~nCache entry added: ~p.~n", [{DB, ObjectID}]),
{ok, {DB, ObjectID}, shr_timed_caches_manager:get_timeout()}.
handle_call (invalidate, _, State) ->
{stop, normal, State};
handle_call (ping, _, State) ->
{noreply, State, shr_timed_caches_manager:get_timeout()}.
handle_cast (invalidate, State) ->
{stop, normal, State};
handle_cast (ping, State) ->
{noreply, State, shr_timed_caches_manager:get_timeout()}.
terminate (_, {DB, ObjectID}) ->
io:format
(
"~nCache entry timed out or was invalidated: ~p.~n",
[{DB, ObjectID}]
),
ets:delete(DB, ObjectID).
code_change (_, State, _) ->
{ok, State}.
format_status (_, [_, State]) ->
[{data, [{"State", State}]}].
handle_info(timeout, State) ->
{stop, normal, State};
handle_info(_, {DB, ObjectID}) ->
{noreply, {DB, ObjectID}, shr_timed_caches_manager:get_timeout()}.
%%%% Interface Functions
-spec fetch (atom(), any(), any()) -> any().
fetch (DB, Owner, ObjectID) ->
io:format("~nfetch from cache: ~p.~n", [{DB, {Owner, ObjectID}}]),
case ets:lookup(DB, {Owner, ObjectID}) of
[] -> add_to_cache(DB, Owner, ObjectID);
[{_, TimerPID, Data}] ->
gen_server:cast(TimerPID, ping),
Data
end.
-spec update (atom(), any(), any(), any()) -> 'ok'.
update (DB, Owner, ObjectID, Data) ->
io:format("~nUpdating cache: ~p.~n", [{DB, {Owner, ObjectID}}]),
case ets:lookup(DB, {Owner, ObjectID}) of
[] -> ok;
[{_OwnerID, TimerPID, _Data}] ->
gen_server:stop(TimerPID)
end,
add_update_to_cache(DB, Owner, ObjectID, Data).
-spec invalidate (atom(), any(), any()) -> 'ok'.
invalidate (DB, Owner, ObjectID) ->
case ets:lookup(DB, {Owner, ObjectID}) of
[] ->
io:format
(
"~nInvalidation request on non-stored entry: ~p.~n",
[{DB, Owner, ObjectID}]
),
ok;
[{_, TimerPID, _}] ->
io:format
(
"~nInvalidation request on stored entry: ~p.~n",
[{DB, Owner, ObjectID}]
),
gen_server:stop(TimerPID),
ok
end.
|
