将Erlang-C端口示例转换为Erlang-Golang。

huangapple
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英文:

Converting Erlang-C port example to Erlang-Golang

问题

我正在尝试为Erlang编写一个Golang驱动程序，通过Erlang端口进行访问。

我已经从Erlang C端口示例开始，它可以正常工作：

http://www.erlang.org/doc/tutorial/c_port.html

现在我正在尝试将C代码移植到Golang；只是尝试回显一个简单的“Hello World\n”消息，使用“\n”作为分隔符。

所以我的Golang代码如下：

  1. package main
  3. import (
  4. 	"bufio"
  5. 	"fmt"
  6. 	"os"
  7. )
  9. func main() {
  10. 	reader := bufio.NewReader(os.Stdin)
  11. 	fmt.Print("Enter text: ")
  12. 	bytes, _ := reader.ReadBytes('\n')
  13. 	os.Stdout.Write(bytes)
  14. }

我可以编译并从命令行运行它，如下所示：

  1. justin@justin-ThinkPad-X240:~/work/erlang_golang_port$ go build -o tmp/echo echo.go
  2. justin@justin-ThinkPad-X240:~/work/erlang_golang_port$ ./tmp/echo
  3. Enter text: hello
  4. hello

然而，当我尝试从Erlang端调用驱动程序（下面是Erlang代码）时，我得到以下错误：

  1. justin@justin-ThinkPad-X240:~/work/erlang_golang_port$ erl
  2. Erlang R16B03 (erts-5.10.4) [source] [64-bit] [smp:4:4] [async-threads:10] [kernel-poll:false]
  4. Eshell V5.10.4  (abort with ^G)
  5. 1> c(complex1).
  6. {ok,complex1}
  7. 2> complex1:start("./tmp/echo").
  8. <0.41.0>
  9. 3> complex1:ping().
  11. =ERROR REPORT==== 23-Apr-2015::08:56:47 ===
  12. Bad value on output port './tmp/echo'

我感觉消息已经成功传递给驱动程序，但我以某种方式错误地返回了响应。

谢谢。

英文:

I'm trying to write a Golang driver for Erlang, accesible via an Erlang port.

I've started with the Erlang C port example, which works fine:

http://www.erlang.org/doc/tutorial/c_port.html

Now I'm trying to port the C code to Golang; just trying to echo a simple 'Hello World\n' message, using '\n' as the delimiter.

So my Golang code is as follows:

  1. package main
  3. import (
  4. 	&quot;bufio&quot;
  5. 	&quot;fmt&quot;
  6. 	&quot;os&quot;
  7. )
  9. func main() {
  10. 	reader := bufio.NewReader(os.Stdin)
  11. 	fmt.Print(&quot;Enter text: &quot;)
  12. 	bytes, _ := reader.ReadBytes(&#39;\n&#39;)
  13. 	os.Stdout.Write(bytes)
  14. }

And I can compile it and run it from the command line as follows:

  1. justin@justin-ThinkPad-X240:~/work/erlang_golang_port$ go build -o tmp/echo echo.go
  2. justin@justin-ThinkPad-X240:~/work/erlang_golang_port$ ./tmp/echo
  3. Enter text: hello
  4. hello

However when I try to call the driver from the Erlang side (Erlang code below) I get the following:

  1. justin@justin-ThinkPad-X240:~/work/erlang_golang_port$ erl
  2. Erlang R16B03 (erts-5.10.4) [source] [64-bit] [smp:4:4] [async-threads:10] [kernel-poll:false]
  4. Eshell V5.10.4  (abort with ^G)
  5. 1&gt; c(complex1).
  6. {ok,complex1}
  7. 2&gt; complex1:start(&quot;./tmp/echo&quot;).
  8. &lt;0.41.0&gt;
  9. 3&gt; complex1:ping().
  11. =ERROR REPORT==== 23-Apr-2015::08:56:47 ===
  12. Bad value on output port &#39;./tmp/echo&#39;

I have the sense that the message is being passed OK to the driver, but that I am somehow returning the response incorrectly.

TIA.

Erlang port code:

  1. -module(complex1).
  3. -export([start/1, stop/0, init/1]).
  5. -export([ping/0]).
  7. -define(HELLO_WORLD, [72, 101, 108, 108, 111, 44, 32, 119, 111, 114, 108, 100, 46]).
  9. start(ExtPrg) -&gt;
  10.     spawn(?MODULE, init, [ExtPrg]).
  12. stop() -&gt;
  13.     complex ! stop.
  15. ping() -&gt;
  16.     call_port({ping, ?HELLO_WORLD++[10]}).
  18. call_port(Msg) -&gt;
  19.     complex ! {call, self(), Msg},
  20.     receive
  21. 	{complex, Result} -&gt;
  22. 	    Result
  23.     end.
  25. init(ExtPrg) -&gt;
  26.     register(complex, self()),
  27.     process_flag(trap_exit, true),
  28.     Port = open_port({spawn, ExtPrg}, [{packet, 2}]),
  29.     loop(Port).
  31. loop(Port) -&gt;
  32.     receive
  33. 	{call, Caller, Msg} -&gt;
  34. 	    Port ! {self(), {command, Msg}},
  35. 	    receive
  36. 		{Port, {data, Data}} -&gt;
  37. 		    Caller ! {complex, Data}
  38. 	    end,
  39. 	    loop(Port);
  40. 	stop -&gt;
  41. 	    Port ! {self(), close},
  42. 	    receive
  43. 		{Port, closed} -&gt;
  44. 		    exit(normal)
  45. 	    end;
  46. 	{&#39;EXIT&#39;, Port, _Reason} -&gt;
  47. 	    exit(port_terminated)
  48.     end.

答案1

得分: 6

echo.go:

  1. package main
  3. import (
  4.     "bufio"
  5.     "os"
  6. )
  8. func main() {
  9.     for {
  10.         reader := bufio.NewReader(os.Stdin)
  11.         bytes, _ := reader.ReadBytes('\n')
  12.         os.Stdout.Write(bytes)
  13.     }
  14. }

complex1.erl:

  1. -module(complex1).
  2. -export([start/1, stop/0, init/1]).
  3. -export([send/1]).
  5. start(ExtPrg) ->
  6.     spawn_link(?MODULE, init, [ExtPrg]).
  7. stop() ->
  8.     complex ! stop.
  10. send(Y) -> call_port({msg, Y}).
  11. call_port({msg, Msg}) ->
  12.     complex ! {call, self(), Msg},
  13.     receive
  14.     {complex, Result} ->
  15.         Result
  16.     end.
  18. init(ExtPrg) ->
  19.     register(complex, self()),
  20.     process_flag(trap_exit, true),
  21.     Port = open_port({spawn, ExtPrg}, []),
  22.     loop(Port).
  24. loop(Port) ->
  25.     receive
  26.     {call, Caller, Msg} ->
  27.         Port ! {self(), {command, Msg++[10]}},
  28.         Data = receive_all(Port, 100),
  29.         Caller ! {complex, Data},
  30.         loop(Port);
  31.     stop ->
  32.         Port ! {self(), close},
  33.         receive {Port, closed} ->
  34.             exit(normal)
  35.         end;
  36.     {'EXIT', Port, Reason} ->
  37.         exit({port_terminated, Reason})
  38.     end.
  40. receive_all(Port, Timeout) -> receive_all(Port, Timeout, []).
  41. receive_all(Port, Timeout, Buffer) ->
  42.     receive
  43.         {Port, {data, Data}} ->
  44.             receive_all(Port, Timeout, [Data | Buffer])
  45.         after Timeout ->
  46.             lists:flatten(lists:reverse(Buffer))
  47.     end.

$ erl

  1. Erlang R16B02_basho8 (erts-5.10.3) [source] [64-bit] [smp:4:4] [async-threads:10] [hipe] [kernel-poll:false]
  3. Eshell V5.10.3  (abort with ^G)
  4. 1> c(complex1).
  5. {ok,complex1}
  6. 2> complex1:start("go run echo.go").
  7. <0.40.0>
  8. 3> complex1:send("asdhadlsjahdslahjdlhd").
  9. "asdhadlsjahdslahjdlhd"
  10. 4> complex1:send("aksdghjakdsgalkdgaldsagdlkagdlkadg").
  11. "aksdghjakdsgalkdgaldsagdlkagdlkadg"
英文:

Posting this answer based on @Justin's follow-up question here, which contains a slightly different but working answer.

echo.go:

  1. package main
  3. import (
  4.     &quot;bufio&quot;
  5.     &quot;os&quot;
  6. )
  8. func main() {
  9.     for{
  10.         reader := bufio.NewReader(os.Stdin)
  11.         bytes, _ := reader.ReadBytes(&#39;\n&#39;)
  12.         os.Stdout.Write(bytes)
  13.     }
  14. }

complex1.erl:

  1. -module(complex1).
  2. -export([start/1, stop/0, init/1]).
  3. -export([send/1]).
  5. start(ExtPrg) -&gt;
  6.     spawn_link(?MODULE, init, [ExtPrg]).
  7. stop() -&gt;
  8.     complex ! stop.
  10. send(Y) -&gt; call_port({msg, Y}).
  11. call_port({msg, Msg}) -&gt;
  12.     complex ! {call, self(), Msg},
  13.     receive
  14.     {complex, Result} -&gt;
  15.         Result
  16.     end.
  18. init(ExtPrg) -&gt;
  19.     register(complex, self()),
  20.     process_flag(trap_exit, true),
  21.     Port = open_port({spawn, ExtPrg}, []),
  22.     loop(Port).
  24. loop(Port) -&gt;
  25.     receive
  26.     {call, Caller, Msg} -&gt;
  27.         Port ! {self(), {command, Msg++[10]}},
  28.         Data = receive_all(Port, 100),
  29.         Caller ! {complex, Data},
  30.         loop(Port);
  31.     stop -&gt;
  32.         Port ! {self(), close},
  33.         receive {Port, closed} -&gt;
  34.             exit(normal)
  35.         end;
  36.     {&#39;EXIT&#39;, Port, Reason} -&gt;
  37.         exit({port_terminated, Reason})
  38.     end.
  40. receive_all(Port, Timeout) -&gt; receive_all(Port, Timeout, []).
  41. receive_all(Port, Timeout, Buffer) -&gt;
  42.     receive
  43.         {Port, {data, Data}} -&gt;
  44.             receive_all(Port, Timeout, [Data | Buffer])
  45.         after Timeout -&gt;
  46.             lists:flatten(lists:reverse(Buffer))
  47.     end.

$ erl

  1. Erlang R16B02_basho8 (erts-5.10.3) [source] [64-bit] [smp:4:4] [async-threads:10] [hipe] [kernel-poll:false]
  3. Eshell V5.10.3  (abort with ^G)
  4. 1&gt; c(complex1).
  5. {ok,complex1}
  6. 2&gt; complex1:start(&quot;go run echo.go&quot;).
  7. &lt;0.40.0&gt;
  8. 3&gt; complex1:send(&quot;asdhadlsjahdslahjdlhd&quot;).
  9. &quot;asdhadlsjahdslahjdlhd&quot;
  10. 4&gt; complex1:send(&quot;aksdghjakdsgalkdgaldsagdlkagdlkadg&quot;).
  11. &quot;aksdghjakdsgalkdgaldsagdlkagdlkadg&quot;

huangapple
  • 本文由 发表于 2015年4月23日 16:07:44
  • 转载请务必保留本文链接：https://go.coder-hub.com/29817331.html
  • erlang
  • erlang-ports
  • go
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