megaphone VI: Waiting for Data

Previously...

• I coded up the get_data function
• I coded up the put_data function
• I coded up the put_data function...again

While coding up the stuff to notify the waiter, I noticed that the code to get the waiter was using the wrong hash table.  Mind you, I knew that when I was making that post!  It was all a test to see if any alert readers would catch that problem.  

But nobody did.

I hope you have all learned an important lesson from this, and it is not that I am a spastic programmer.  Who makes tons of mistakes.  Yeah, well, anyways, here is the revised version of remove_waiter:

remove_waiter(ConnectionID, State) ->

    Table = State#megaphone_main_state.waiters,

    case dict:is_key(ConnectionID, Table) of

        false -> { undefined, State};

        true ->

            { Waiter, NewTable } = case dict:fetch(ConnectionID, Table) of

                [ PID | Rest ] ->

                    UpdatedTable = dict:store(ConnectionID, Rest, Table),

                    { PID, UpdatedTable};

                [] ->

                    UpdatedTable = dict:erase(ConnectionID, Table),

                    { undefined, UpdatedTable}

            end,

            NewState = State#megaphone_main_state{waiters = NewTable},

            { Waiter, NewState }

    end.

And here is the code for notify_waiter:

notify_waiter(Waiter, ConnectionID, State) ->

    Table = State#megaphone_main_state.connectionToResults,

    case dict:is_key(ConnectionID, Table) of

        false ->

            ?ERROR_MSG("could not find data that we were just asked to deliver!  Connection ID: ~p", [ConnectionID]),

            State;

        true ->

            case dict:fetch (ConnectionID, Table) of

                [ Head | Tail ] ->

                    Waiter ! { ok, Head },

                    NewTable = dict:store(ConnectionID, Tail, Table),

                    State#megaphone_main_state{connectionToResults = NewTable};

                [] ->

                    ?ERROR_MSG("Data we were supposed to deliver is missing for connection ID: ~p", [ConnectionID]),

                    NewTable = dict:erase(ConnectionID, Table),

                    State#megaphone_main_state{connectionToResults = NewTable}

            end

    end.

For next time, parsing HTTP packets.