diff options
Diffstat (limited to 'src/gen_server2.erl')
| -rw-r--r-- | src/gen_server2.erl | 147 |
1 files changed, 81 insertions, 66 deletions
diff --git a/src/gen_server2.erl b/src/gen_server2.erl index 4056e3d9..507d1cda 100644 --- a/src/gen_server2.erl +++ b/src/gen_server2.erl @@ -16,12 +16,15 @@ %% The original code could reorder messages when communicating with a %% process on a remote node that was not currently connected. %% -%% 4) The callback module can optionally implement prioritise_call/3, -%% prioritise_cast/2 and prioritise_info/2. These functions take -%% Message, From and State or just Message and State and return a -%% single integer representing the priority attached to the message. -%% Messages with higher priorities are processed before requests with -%% lower priorities. The default priority is 0. +%% 4) The callback module can optionally implement prioritise_call/4, +%% prioritise_cast/3 and prioritise_info/3. These functions take +%% Message, From, Length and State or just Message, Length and State +%% (where Length is the current number of messages waiting to be +%% processed) and return a single integer representing the priority +%% attached to the message, or 'drop' to ignore it (for +%% prioritise_cast/3 and prioritise_info/3 only). Messages with +%% higher priorities are processed before requests with lower +%% priorities. The default priority is 0. %% %% 5) The callback module can optionally implement %% handle_pre_hibernate/1 and handle_post_hibernate/1. These will be @@ -72,6 +75,12 @@ %% format_message_queue/2 which is the equivalent of format_status/2 %% but where the second argument is specifically the priority_queue %% which contains the prioritised message_queue. +%% +%% 9) The function with_state/2 can be used to debug a process with +%% heavyweight state (without needing to copy the entire state out of +%% process as sys:get_status/1 would). Pass through a function which +%% can be invoked on the state, get back the result. The state is not +%% modified. %% All modifications are (C) 2009-2013 VMware, Inc. @@ -181,6 +190,7 @@ cast/2, reply/2, abcast/2, abcast/3, multi_call/2, multi_call/3, multi_call/4, + with_state/2, enter_loop/3, enter_loop/4, enter_loop/5, enter_loop/6, wake_hib/1]). %% System exports @@ -196,8 +206,7 @@ %% State record -record(gs2_state, {parent, name, state, mod, time, - timeout_state, queue, debug, prioritise_call, - prioritise_cast, prioritise_info}). + timeout_state, queue, debug, prioritisers}). -ifdef(use_specs). @@ -380,6 +389,16 @@ multi_call(Nodes, Name, Req, Timeout) when is_list(Nodes), is_atom(Name), is_integer(Timeout), Timeout >= 0 -> do_multi_call(Nodes, Name, Req, Timeout). +%% ----------------------------------------------------------------- +%% Apply a function to a generic server's state. +%% ----------------------------------------------------------------- +with_state(Name, Fun) -> + case catch gen:call(Name, '$with_state', Fun, infinity) of + {ok,Res} -> + Res; + {'EXIT',Reason} -> + exit({Reason, {?MODULE, with_state, [Name, Fun]}}) + end. %%----------------------------------------------------------------- %% enter_loop(Mod, Options, State, <ServerName>, <TimeOut>, <Backoff>) ->_ @@ -638,17 +657,22 @@ adjust_timeout_state(SleptAt, AwokeAt, {backoff, CurrentTO, MinimumTO, {backoff, CurrentTO1, MinimumTO, DesiredHibPeriod, RandomState1}. in({'$gen_cast', Msg} = Input, - GS2State = #gs2_state { prioritise_cast = PC }) -> - in(Input, PC(Msg, GS2State), GS2State); + GS2State = #gs2_state { prioritisers = {_, F, _} }) -> + in(Input, F(Msg, GS2State), GS2State); in({'$gen_call', From, Msg} = Input, - GS2State = #gs2_state { prioritise_call = PC }) -> - in(Input, PC(Msg, From, GS2State), GS2State); + GS2State = #gs2_state { prioritisers = {F, _, _} }) -> + in(Input, F(Msg, From, GS2State), GS2State); +in({'$with_state', _From, _Fun} = Input, GS2State) -> + in(Input, 0, GS2State); in({'EXIT', Parent, _R} = Input, GS2State = #gs2_state { parent = Parent }) -> in(Input, infinity, GS2State); in({system, _From, _Req} = Input, GS2State) -> in(Input, infinity, GS2State); -in(Input, GS2State = #gs2_state { prioritise_info = PI }) -> - in(Input, PI(Input, GS2State), GS2State). +in(Input, GS2State = #gs2_state { prioritisers = {_, _, F} }) -> + in(Input, F(Input, GS2State), GS2State). + +in(_Input, drop, GS2State) -> + GS2State; in(Input, Priority, GS2State = #gs2_state { queue = Queue }) -> GS2State # gs2_state { queue = priority_queue:in(Input, Priority, Queue) }. @@ -658,6 +682,10 @@ process_msg({system, From, Req}, %% gen_server puts Hib on the end as the 7th arg, but that version %% of the fun seems not to be documented so leaving out for now. sys:handle_system_msg(Req, From, Parent, ?MODULE, Debug, GS2State); +process_msg({'$with_state', From, Fun}, + GS2State = #gs2_state{state = State}) -> + reply(From, catch Fun(State)), + loop(GS2State); process_msg({'EXIT', Parent, Reason} = Msg, GS2State = #gs2_state { parent = Parent }) -> terminate(Reason, Msg, GS2State); @@ -864,13 +892,19 @@ dispatch(Info, Mod, State) -> common_reply(_Name, From, Reply, _NState, [] = _Debug) -> reply(From, Reply), []; -common_reply(Name, From, Reply, NState, Debug) -> - reply(Name, From, Reply, NState, Debug). +common_reply(Name, {To, _Tag} = From, Reply, NState, Debug) -> + reply(From, Reply), + sys:handle_debug(Debug, fun print_event/3, Name, {out, Reply, To, NState}). -common_debug([] = _Debug, _Func, _Info, _Event) -> +common_noreply(_Name, _NState, [] = _Debug) -> []; -common_debug(Debug, Func, Info, Event) -> - sys:handle_debug(Debug, Func, Info, Event). +common_noreply(Name, NState, Debug) -> + sys:handle_debug(Debug, fun print_event/3, Name, {noreply, NState}). + +common_become(_Name, _Mod, _NState, [] = _Debug) -> + []; +common_become(Name, Mod, NState, Debug) -> + sys:handle_debug(Debug, fun print_event/3, Name, {become, Mod, NState}). handle_msg({'$gen_call', From, Msg}, GS2State = #gs2_state { mod = Mod, state = State, @@ -887,23 +921,11 @@ handle_msg({'$gen_call', From, Msg}, GS2State = #gs2_state { mod = Mod, loop(GS2State #gs2_state { state = NState, time = Time1, debug = Debug1}); - {noreply, NState} -> - Debug1 = common_debug(Debug, fun print_event/3, Name, - {noreply, NState}), - loop(GS2State #gs2_state {state = NState, - time = infinity, - debug = Debug1}); - {noreply, NState, Time1} -> - Debug1 = common_debug(Debug, fun print_event/3, Name, - {noreply, NState}), - loop(GS2State #gs2_state {state = NState, - time = Time1, - debug = Debug1}); {stop, Reason, Reply, NState} -> {'EXIT', R} = (catch terminate(Reason, Msg, GS2State #gs2_state { state = NState })), - reply(Name, From, Reply, NState, Debug), + common_reply(Name, From, Reply, NState, Debug), exit(R); Other -> handle_common_reply(Other, Msg, GS2State) @@ -916,28 +938,24 @@ handle_common_reply(Reply, Msg, GS2State = #gs2_state { name = Name, debug = Debug}) -> case Reply of {noreply, NState} -> - Debug1 = common_debug(Debug, fun print_event/3, Name, - {noreply, NState}), - loop(GS2State #gs2_state { state = NState, - time = infinity, - debug = Debug1 }); + Debug1 = common_noreply(Name, NState, Debug), + loop(GS2State #gs2_state {state = NState, + time = infinity, + debug = Debug1}); {noreply, NState, Time1} -> - Debug1 = common_debug(Debug, fun print_event/3, Name, - {noreply, NState}), - loop(GS2State #gs2_state { state = NState, - time = Time1, - debug = Debug1 }); + Debug1 = common_noreply(Name, NState, Debug), + loop(GS2State #gs2_state {state = NState, + time = Time1, + debug = Debug1}); {become, Mod, NState} -> - Debug1 = common_debug(Debug, fun print_event/3, Name, - {become, Mod, NState}), + Debug1 = common_become(Name, Mod, NState, Debug), loop(find_prioritisers( GS2State #gs2_state { mod = Mod, state = NState, time = infinity, debug = Debug1 })); {become, Mod, NState, Time1} -> - Debug1 = common_debug(Debug, fun print_event/3, Name, - {become, Mod, NState}), + Debug1 = common_become(Name, Mod, NState, Debug), loop(find_prioritisers( GS2State #gs2_state { mod = Mod, state = NState, @@ -957,12 +975,6 @@ handle_common_termination(Reply, Msg, GS2State) -> terminate({bad_return_value, Reply}, Msg, GS2State) end. -reply(Name, {To, Tag}, Reply, State, Debug) -> - reply({To, Tag}, Reply), - sys:handle_debug( - Debug, fun print_event/3, Name, {out, Reply, To, State}). - - %%----------------------------------------------------------------- %% Callback functions for system messages handling. %%----------------------------------------------------------------- @@ -1165,30 +1177,33 @@ whereis_name(Name) -> end. find_prioritisers(GS2State = #gs2_state { mod = Mod }) -> - PrioriCall = function_exported_or_default( - Mod, 'prioritise_call', 3, - fun (_Msg, _From, _State) -> 0 end), - PrioriCast = function_exported_or_default(Mod, 'prioritise_cast', 2, - fun (_Msg, _State) -> 0 end), - PrioriInfo = function_exported_or_default(Mod, 'prioritise_info', 2, - fun (_Msg, _State) -> 0 end), - GS2State #gs2_state { prioritise_call = PrioriCall, - prioritise_cast = PrioriCast, - prioritise_info = PrioriInfo }. + PCall = function_exported_or_default(Mod, 'prioritise_call', 4, + fun (_Msg, _From, _State) -> 0 end), + PCast = function_exported_or_default(Mod, 'prioritise_cast', 3, + fun (_Msg, _State) -> 0 end), + PInfo = function_exported_or_default(Mod, 'prioritise_info', 3, + fun (_Msg, _State) -> 0 end), + GS2State #gs2_state { prioritisers = {PCall, PCast, PInfo} }. function_exported_or_default(Mod, Fun, Arity, Default) -> case erlang:function_exported(Mod, Fun, Arity) of true -> case Arity of - 2 -> fun (Msg, GS2State = #gs2_state { state = State }) -> - case catch Mod:Fun(Msg, State) of + 3 -> fun (Msg, GS2State = #gs2_state { queue = Queue, + state = State }) -> + Length = priority_queue:len(Queue), + case catch Mod:Fun(Msg, Length, State) of + drop -> + drop; Res when is_integer(Res) -> Res; Err -> handle_common_termination(Err, Msg, GS2State) end end; - 3 -> fun (Msg, From, GS2State = #gs2_state { state = State }) -> - case catch Mod:Fun(Msg, From, State) of + 4 -> fun (Msg, From, GS2State = #gs2_state { queue = Queue, + state = State }) -> + Length = priority_queue:len(Queue), + case catch Mod:Fun(Msg, From, Length, State) of Res when is_integer(Res) -> Res; Err -> |