Erlang 新手 - 并发和消息传递

Question

我对编程和全新的 erlang 还是个新手（2 周的新手！）。我稍微编辑了一下，至少它会编译并且运行。但我仍然无法弄清楚将结果发送到 "joiner process" 以加入所有单独结果的概念。

它确实拆分并发送 "chunks" 接收到的数据块来计算块数。只是不知道如何让所有这些过程加入他们各自的结果。我有点理解下面的概念，但不知道它是如何实现的。我已经尝试了很多天和几个小时来达到这一点，但是如果没有错误或未绑定变量等，我无法让它做任何事情。

-module (ccharcount1d).
-compile(export_all).

load(F)->
 {ok, Bin} = file:read_file(F),
  List=binary_to_list(Bin),
  Ls=string:to_lower(List),
  Length=round(length(List)/20),
  Collect_Results = spawn(ccharcount1d, collect_results, []),

  Sl=split(Ls,Length),

  io:fwrite("Loaded, Split, and sent to multiple processes~n").




%%splits txt file into "chunks" and sends those "chunks" to be processed 
split([],_)->[];
split(List,Length)->
S1=string:substr(List,1,Length),
case length(List) > Length of
   true->S2=string:substr(List,Length+1,length(List)),
   Process_Split = spawn(ccharcount1d,receive_splits,[]),
   Process_Split ! {self(), S1};

   false->S2=[],
   Process_Split = spawn(ccharcount1d,receive_splits,[]),
   Process_Split ! {self(), S1}   

 end,  

[S1]++split(S2,Length).


%%recieves the split "chunks" and counts the results 
receive_splits()-> 
    receive
        {From, S1} -> 
            Result=go(S1)
            %Collect_Results ! Result
    end.



collect_results()-> 
    receive
        {Process_Split, Result} ->
            Result=join([],Result)
    end.



join([],[])->[];
join([],R)->R;
join([H1 |T1],[H2|T2])->
{C,N}=H1,
{C1,N1}=H2,
[{C1,N+N1}]++join(T1,T2).



count(Ch, [],N)->N;
count(Ch, [H|T],N) ->
   case Ch==H of
   true-> count(Ch,T,N+1);
   false -> count(Ch,T,N)
end.

go(L)->
Alph=[$a,$b,$c,$d,$e,$f,$g,$h,$i,$j,$k,$l,$m,$n,$o,$p,$q,$r,$s,$t,$u,$v,$w,$x,$y,$z],
rgo(Alph,L,[]).

rgo([H|T],L,Result)->
N=count(H,L,0),
Result2=Result++[{[H],N}],
rgo(T,L,Result2);


rgo([],L,Result)-> Result.

Answer 1

您需要同步go函数的输出。不要在 go 中生成函数，因为我看到所有结果都将进入不同的过程（receive_results）。

最好的解决方案是只在加载函数中产生一个用于连接结果的进程（此过程将 self() 作为输入，以便它可以将最终结果发送回加载函数）。然后传递该连接进程引用（J_PID) 发送回结果以加入的所有工作进程 process.Join 进程是一种循环 receive_results.Loop 当所有块都是 processed.Add 终止加入的子句时终止 process.While终止，加入过程会将结果发送回加载函数。

Sudo 代码：

J_PID = spawn join(self())
溢出(J_PID,....)
wait_for_result（接收结果 -> R）

Answer 2

again, i'm new. I'm understanding the concept. I'm not understanding the syntax. the how to "pass a Pid to a worker process"

start() ->
    Work = ...,
    JoinPid = spawn(fun() -> join_func([]) end),  
    WorkerPid = spawn(fun() -> worker_func(JoinPid, Work) end),  %Pass JoinPid to worker process.
    ...

join_func(Acc) ->
    receive
        Result ->
            join_func([Result|Acc]);  %Recursive function call--the life blood of all functional languages.

        ...
    end

worker_func(JoinPid, Work) ->
    Result = ... Work ...,
    JoinPid ! Result.  %Worker process uses JoinPid to send back the results.

另外，看看这个：

8> [$a, $b, $c].
"abc"

9> "abc".
"abc"

输出显示 [$a, $b, $c] 等同于 "abc"。这意味着你可以这样写：

[$a,$b,$c,$d,$e,$f,$g,$h,$i,$j,$k,$l,$m,$n,$o,$p,$q,$r,$s,$t,$u,$v,$w,$x,$y,$z]

像这样更简洁：

"abcdefghijklmnopqrstuvwxyz"

更甚者，像这样：

11> lists:seq(97, 122).
"abcdefghijklmnopqrstuvwxyz"

Erlang 新手 - 并发和消息传递

Erlang newbie - concurrency and message passing

concurrency

erlang

spawn

erl

spawning