,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{name=Name
+ ,cell_state=CellState
,neighbors=Neighbors
,num_neighbors=NumNeighbors
+ ,early_msgs=EarlyMsgs
}=State) ->
- ok = cast_all(Neighbors, {request_state, GenID, Name}),
- {noreply, State#state{replies_pending=NumNeighbors, gen_id=GenID}};
+ ok = life_lib:cast_one2all(Neighbors, {state_broadcast, GenID, CellState}),
-%% If we receive this 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.)
-handle_cast({request_state, GenID, _Requester}=Msg,
- #state{gen_id=MyGenID
- ,name=Name
- }=State) when GenID =/= MyGenID->
+ % Put stashed messages back in the mailbox,
+ % now that we're ready to handle them
+ ok = life_lib:cast_all2one(Name, EarlyMsgs),
- gen_server:cast(Name, Msg),
- {noreply, State};
+ NewState = State#state{replies_pending=NumNeighbors
+ ,gen_id=GenID
+ ,early_msgs=[]
+ },
+
+ {noreply, NewState};
-%% Now that we can be sure that this request is for the current generation, we
-%% can handle it
-handle_cast({request_state, GenID, Requester},
- #state{gen_id=MyGenID
- ,cell_state=CellState
- }=State) when GenID =:= MyGenID->
- ok = gen_server:cast(Requester, {response_state, MyGenID, CellState}),
- {noreply, State};
+%% 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 ->
-handle_cast({response_state, GenID, NeighborState},
+ {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
{noreply, NewState}
end;
-handle_cast(_Msg, State) ->
- {noreply, State}.
-
-handle_info(_Msg, State) ->
+handle_cast(_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;