erlang_producer_consumer_example.erl

-module(pc_queue).

-export([start/0,produce/2,consume/1,status/1]).

start() ->
    Queue = queue:new(),
    spawn(fun() -> loop(Queue) end).

loop(Q) ->
    receive
        {produce,Msg} ->
            io:format("Produce msg: ~p~n",[Msg]),
            NewQ = queue:in(Msg,Q),
            loop(NewQ);
        consume ->
            case queue:out(Q) of
                {{value,Msg}, NewQ} ->
                    io:format("Consume msg: ~p~n",[Msg]),
                    loop(NewQ);
                {empty,_} ->
                    io:format(" -> no msg in queue~n"),
                    loop(Q)
            end;
        status ->
            io:format("QUEUE: ~p~n",[Q]),
            loop(Q);
        Command ->
            io:format(" -> ERROR: invalid command: ~p~n",[Command]),
            loop(Q)
    end.

produce(QPid, Msg) ->
    QPid ! {produce, Msg}.

consume(QPid) ->
    QPid ! consume.

status(QPid) ->
    QPid ! status.