第一出处 http://pascal4123.javaeye.com/admin/blogs/434927
2009-07-28
erlang-python port 程序
作者:pascal4123
把
书上第12章那个erlang-c的例子改编了下,把C程序改写成了python程序。在ubuntu8.04 + erlang5.6.5 + python2.5.2上调试通过。
erlang side: example2.erl
- -module(example2).
- -export([start/0, stop/0]).
- -export([twice/1, sum/2]).
-
- start() ->
- spawn(fun() ->
- register(example1, self()),
- process_flag(trap_exit, true),
- Port = open_port({spawn, "python -u ./example2.py"}, [{packet, 2}]),
- loop(Port)
- end).
-
- stop() ->
- example1 ! stop.
-
- twice(X) -> call_port({twice, X}).
- sum(X,Y) -> call_port({sum, X, Y}).
-
- call_port(Msg) ->
- example1 ! {call, self(), Msg},
- receive
- {example1, Result} ->
- Result
- end.
-
- loop(Port) ->
- receive
- {call, Caller, Msg} ->
- Port ! {self(), {command, encode(Msg)}},
- receive
- {Port, {data, Data}} ->
- Caller ! {example1, decode(Data)}
- end,
- loop(Port);
- stop ->
- Port ! {self(), close},
- receive
- {Port, closed} ->
- exit(normal)
- end;
- {'EXIT', Port, Reason} ->
- exit({port_terminated,Reason})
- end.
-
- encode({twice, X}) -> [1, X];
- encode({sum, X, Y}) -> [2, X, Y].
-
- decode([Int]) -> Int.
-module(example2).
-export([start/0, stop/0]).
-export([twice/1, sum/2]).
start() ->
spawn(fun() ->
register(example1, self()),
process_flag(trap_exit, true),
Port = open_port({spawn, "python -u ./example2.py"}, [{packet, 2}]),
loop(Port)
end).
stop() ->
example1 ! stop.
twice(X) -> call_port({twice, X}).
sum(X,Y) -> call_port({sum, X, Y}).
call_port(Msg) ->
example1 ! {call, self(), Msg},
receive
{example1, Result} ->
Result
end.
loop(Port) ->
receive
{call, Caller, Msg} ->
Port ! {self(), {command, encode(Msg)}},
receive
{Port, {data, Data}} ->
Caller ! {example1, decode(Data)}
end,
loop(Port);
stop ->
Port ! {self(), close},
receive
{Port, closed} ->
exit(normal)
end;
{'EXIT', Port, Reason} ->
exit({port_terminated,Reason})
end.
encode({twice, X}) -> [1, X];
encode({sum, X, Y}) -> [2, X, Y].
decode([Int]) -> Int.
需要注意的是调用python程序,要使用参数-u。强制标准输入/输出不得有缓存,要立时反应。
python官方文档对-u的解释: Force stdin, stdout and stderr to be totally unbuffered.
python side: example2.py
- import sys, os
- import struct
-
- def recv():
- buf = sys.stdin.read(2)
- if len(buf) == 2:
- (sz, ) = struct.unpack("!h", buf)
- payload = sys.stdin.read(sz)
- return payload
- else:
- return None
-
- def send(payload):
- sz = len(payload)
- header= struct.pack("!h", sz)
- return sys.stdout.write( header + payload )
-
- def twice(arg1):
- return 2*arg1
-
- def sum(arg1,arg2):
- return arg1+arg2
-
- def main_loop():
- buf = recv()
- while buf:
- xa = struct.unpack("!%dB" % len(buf), buf)
- if xa[0] == 1:
- calc_res = twice(xa[1])
- elif xa[0] == 2:
- calc_res = sum(xa[1], xa[2])
- result = struct.pack('!B', calc_res)
- send(result)
- buf = recv()
- return None
-
- if __name__ == '__main__':
- main_loop()
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