python popen sqlplus_Python基于Select模型实现Popen输出

参考了pssh的代码，实现了下面一个小的框架，用于实现并发处理涉及到的IO返回的标准输出和错误输出。IOMap里面保存了所有可读句柄对应的call函数。一旦select返回就read返回然后相应的处理，直接看代码吧。

#!/usr/bin/env python

#coding=utf-8

import os

import signal

import select, sys, subprocess

BUFFER_SIZE = 1024

class IOMap(object):

"""A manager for file descriptors and their associated handlers.

The poll method dispatches events to the appropriate handlers.

"""

def __init__(self):

self.readmap = {}

self.writemap = {}

wakeup_readfd, wakeup_writefd = os.pipe()

self.register_read(wakeup_readfd, self.wakeup_handler)

# TODO: remove test when we stop supporting Python <2.5

if hasattr(signal, 'set_wakeup_fd'):

signal.set_wakeup_fd(wakeup_writefd)

self.wakeup_writefd = None

else:

self.wakeup_writefd = wakeup_writefd

def register_read(self, fd, handler):

"""Registers an IO handler for a file descriptor for reading."""

self.readmap[fd] = handler

def register_write(self, fd, handler):

"""Registers an IO handler for a file descriptor for writing."""

self.writemap[fd] = handler

def unregister(self, fd):

"""Unregisters the given file descriptor."""

if fd in self.readmap:

del self.readmap[fd]

if fd in self.writemap:

del self.writemap[fd]

def poll(self, timeout=None):

"""Performs a poll and dispatches the resulting events."""

if not self.readmap and not self.writemap:

return

rlist = list(self.readmap)

wlist = list(self.writemap)

try:

rlist, wlist, _ = select.select(rlist, wlist, [], timeout)

except select.error:

_, e, _ = sys.exc_info()

errno = e.args[0]

if errno == EINTR:

return

else:

raise

for fd in rlist:

handler = self.readmap[fd]

handler(fd, self)

for fd in wlist:

handler = self.writemap[fd]

handler(fd, self)

def wakeup_handler(self, fd, iomap):

"""Handles read events on the signal wakeup pipe.

This ensures that SIGCHLD signals aren't lost.

"""

try:

os.read(fd, READ_SIZE)

except (OSError, IOError):

_, e, _ = sys.exc_info()

errno, message = e.args

if errno != EINTR:

sys.stderr.write('Fatal error reading from wakeup pipe: %s\n'% message)

raise FatalError

class Task(object):

"""docstring for Task"""

def __init__(self,):

self.stdout = ""

self.stderr = ""

def run(self, io_map):

"""run command in Popen

print stdout and stderr

"""

test_pipe = subprocess.Popen('i=0;while [ $i -lt 1000 ];do echo "hello world $i";abcd;let i++;done', shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)

self.stdout = test_pipe.stdout

self.stderr = test_pipe.stderr

io_map.register_read(self.stdout.fileno(), self.handle_stdout)

io_map.register_read(self.stderr.fileno(), self.handle_stderr)

while True:

try:

io_map.poll()

except KeyboardInterrupt:

# This exception handler doesn't print out any fancy status

# information--it just stops.

self.interrupted()

def handle_stdout(self, fd, iomap):

""" handle Popen return stdout

"""

try:

buf = os.read(fd, BUFFER_SIZE)

if buf:

print "stdout : " + buf,

else:

self.close_stdout(iomap)

except (OSError, IOError):

_, e, _ = sys.exc_info()

if e.errno != EINTR:

self.close_stdout(iomap)

pass

def handle_stderr(self, fd, iomap):

""" handle Popen return stderr

"""

try:

buf = os.read(fd, BUFFER_SIZE)

if buf:

print "stderr : " + buf,

else:

self.close_stderr(iomap)

except (OSError, IOError):

_, e, _ = sys.exc_info()

if e.errno != EINTR:

self.close_stderr(iomap)

pass

def close_stderr(self, iomap):

if self.stderr:

iomap.unregister(self.stderr.fileno())

def close_stdout(self, iomap):

if self.stdout:

iomap.unregister(self.stdout.fileno())

def interrupted(self):

"""Cleans up after a keyboard interrupt."""

sys.exit(255)

if __name__ == '__main__':

iomap = IOMap()

task = Task()

task.run(iomap)