,num_neighbors :: integer()
,replies_pending :: integer()
,gen_id :: integer()
+ ,early_msgs :: list()
}).
gen_server:start_link(ServerName, ?MODULE, Args, Opts).
+%% ============================================================================
+%% Callbacks (unused)
+%% ============================================================================
+
+handle_call(_Msg, _From, State) -> {reply, ok, State}.
+handle_info(_Msg, State) -> {noreply, State}.
+code_change(_Old, State, _Other) -> {ok, State}.
+terminate(_Reason, State) -> {ok, State}.
+
+
%% ============================================================================
%% Callbacks
%% ============================================================================
,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{cell_state=CellState
+ #state{name=Name
+ ,cell_state=CellState
,neighbors=Neighbors
,num_neighbors=NumNeighbors
+ ,early_msgs=EarlyMsgs
}=State) ->
- ok = cast_all(Neighbors, {state_broadcast, GenID, CellState}),
- {noreply, State#state{replies_pending=NumNeighbors, gen_id=GenID}};
+ ok = life_lib:cast_one2all(Neighbors, {state_broadcast, GenID, CellState}),
+
+ % Put stashed messages back in the mailbox,
+ % now that we're ready to handle them
+ ok = life_lib:cast_all2one(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', throw it back
-%% in the queue. (Took me a while to realize this, but sometimes it is
-%% possible. The more there're cells, the more likely this is to happen.)
+%% 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, name=Name}=State) when GenID =/= ReceivedGenID->
- gen_server:cast(Name, Msg),
- {noreply, State};
+ #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
{noreply, State}.
-handle_info(_Msg, State) ->
- {noreply, State}.
-
-
%% ============================================================================
%% Internal
%% ============================================================================
-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;