如何在 Erlang 中对多个值使用发送接收？

Question

I have the following loops:

for( i = 1 ; i < V ; i++ )
{
    i sends "hi" to arr[i]
}

for( i = 1 ; i <arr.size ; i++ )
{
    if arr[i] receives "hi"
    {
        print "bye"
    }
}

How can i implement these codes in erlang?

I understood the simple ping and pong, but I want to create this code in parallel, so as to balance out the load. I am somewhat confused on the loop implementation part.

Answer 1

Here is an example of what you can do:

-module(a).
-compile(export_all).

worker() ->
    receive
        {hi, From} ->
            From ! {bye, self()},
            worker();
        stop ->
            io:format("Worker ~w terminated.~n", [self()]);
        _Other ->
            io:format("Bad message received by worker: ~w~n", [self()]),
            worker()
    end.


create_workers(N) ->
    create_workers(N, _Pids=[]).

create_workers(0, Pids) -> Pids;
create_workers(N, Pids) ->
    Pid = spawn(a, worker, []),
    create_workers(N-1, [Pid|Pids]).

test()->
    N = 4,
    Workers = create_workers(N),
    RandNum1 = rand:uniform(N),
    RandNum2 = rand:uniform(N),
    Worker1 = lists:nth(RandNum1, Workers),
    Worker2 = lists:nth(RandNum2, Workers),

    Worker1 ! hello,
    Worker1 ! {hi, self()},

    Worker2 ! {xxxx, self()},
    Worker2 ! {hi, self()},

    Results = get_results(2, _Acc=[]),
    io:format("Worker results: ~w~n", [Results]),
    terminate(Workers).


get_results(0, Acc) -> Acc;
get_results(N, Acc) ->
    Result = receive
                 {Msg, _From} -> Msg
             end,
    get_results(N-1, [Result|Acc]).

terminate(Workers) ->
    lists:foreach(fun(Worker) -> Worker ! stop end,
            Workers).

In the shell:

6> c(a).    
a.erl:2: Warning: export_all flag enabled - all functions will be exported
{ok,a}

7> a:test().
Worker results: [bye,bye]
Bad message received by worker: <0.96.0>
Bad message received by worker: <0.99.0>
Worker <0.96.0> terminated.
Worker <0.99.0> terminated.
Worker <0.98.0> terminated.
Worker <0.97.0> terminated.
ok