+++ /dev/null
--module(life_cell).
--behaviour(gen_server).
-
-
-%% API
--export([start_link/1]).
-
-%% Callbacks
--export([init/1
- ,handle_call/3
- ,handle_cast/2
- ,handle_info/2
- ,terminate/2
- ,code_change/3
- ]).
-
-
--record(state, {cell_id :: integer()
- ,name :: string()
- ,cell_state :: 0 | 1
- ,neighbors :: list(atom())
- ,live_neighbors :: integer()
- ,num_neighbors :: integer()
- ,replies_pending :: integer()
- ,gen_id :: integer()
- ,early_msgs :: list()
- }).
-
-
-%% ============================================================================
-%% API
-%% ============================================================================
-
-start_link({_, Name, _}=Datum) ->
- ServerName = {local, Name},
- Args = [Datum],
- Opts = [],
- gen_server:start_link(ServerName, ?MODULE, Args, Opts).
-
-
-%% ============================================================================
-%% Callbacks
-%% ============================================================================
-
-init([{CellID, Name, NeighborNames}]) ->
- State = #state{cell_id = CellID
- ,name = Name
- ,cell_state = crypto:rand_uniform(0, 2)
- ,neighbors = NeighborNames
- ,num_neighbors = length(NeighborNames)
- ,live_neighbors = 0
- ,replies_pending = 0
- ,early_msgs = []
- },
- {ok, State}.
-
-
-terminate(_Reason, State) ->
- {ok, State}.
-
-
-code_change(_Old, State, _Other) ->
- {ok, State}.
-
-
-handle_call(_Msg, _From, State) ->
- {reply, ok, State}.
-
-
-handle_cast({next_gen, GenID},
- #state{name=Name
- ,cell_state=CellState
- ,neighbors=Neighbors
- ,num_neighbors=NumNeighbors
- ,early_msgs=EarlyMsgs
- }=State) ->
-
- ok = cast_all(Neighbors, {state_broadcast, GenID, CellState}),
-
- % Put stashed messages back in the mailbox,
- % now that we're ready to handle them
- ok = cast_to(Name, EarlyMsgs),
-
- NewState = State#state{replies_pending=NumNeighbors
- ,gen_id=GenID
- ,early_msgs=[]
- },
-
- {noreply, NewState};
-
-
-%% If we receive 'state_broadcast' before we receive 'next_gen',
-%% stash it until we do.
-%%
-%% Took me a while to realize this, but sometimes it is possible. The more
-%% there're cells, the more likely this is to happen.
-%%
-handle_cast({state_broadcast, ReceivedGenID, _NeighborState}=Msg,
- #state{gen_id=GenID
- ,early_msgs=EarlyMsgs
- }=State) when GenID =/= ReceivedGenID ->
-
- {noreply, State#state{early_msgs=[Msg|EarlyMsgs]}};
-
-
-%% Now that we can be sure that this request is for the current generation, we
-%% can handle it
-handle_cast({state_broadcast, GenID, NeighborState},
- #state{cell_id=CellID
- ,gen_id=GenID
- ,replies_pending=Pending
- ,cell_state=CellState
- ,live_neighbors=LiveNeighbors
- }=State) ->
-
- NewPending = Pending - 1,
- NewLiveNeighbors = LiveNeighbors + NeighborState,
-
- NewState = State#state{replies_pending=NewPending
- ,live_neighbors=NewLiveNeighbors
- },
-
- case NewPending of
- 0 ->
- NewCellState = new_state(CellState, NewLiveNeighbors),
- ok = life_time:report_state(CellID, GenID, NewCellState),
-
- {noreply, NewState#state{live_neighbors=0
- ,cell_state=NewCellState
- }
- };
-
- _N ->
- {noreply, NewState}
- end;
-
-
-handle_cast(_Msg, State) ->
- {noreply, State}.
-
-
-handle_info(_Msg, State) ->
- {noreply, State}.
-
-
-%% ============================================================================
-%% Internal
-%% ============================================================================
-
-% Cast different messages to a single destination
-cast_to(_, []) -> ok;
-cast_to(Server, [Msg | Msgs]) ->
- ok = gen_server:cast(Server, Msg),
- cast_to(Server, Msgs).
-
-
-% Cast the same message to multiple destinations
-cast_all([], _) -> ok;
-cast_all([Server | Servers], Msg) ->
- ok = gen_server:cast(Server, Msg),
- cast_all(Servers, Msg).
-
-
-new_state(1, LiveNeighbors) when LiveNeighbors < 2 -> 0;
-new_state(1, LiveNeighbors) when LiveNeighbors < 4 -> 1;
-new_state(1, LiveNeighbors) when LiveNeighbors > 3 -> 0;
-new_state(0, LiveNeighbors) when LiveNeighbors =:= 3 -> 1;
-new_state(State, _LiveNeighbors) -> State.
home / code / cellular-automata.git / blobdiff