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Initial refactor of task dependency system....
Initial refactor of task dependency system. We are thinking about refactoring the task dependency system. Currently is is based on engine properties and a function sent with each task. In this commit, I have added a TaskRejectError that tasks can raise to indicate that the engine doesn't have the required dependencies. For now I have not removed any of the old stuff, but I have added warnings that we might remove the older *_prop* methods in IMultiEngine. See this ticket for more info: https://bugs.launchpad.net/bugs/361419

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pipedprocess.py
74 lines | 2.5 KiB | text/x-python | PythonLexer
# encoding: utf-8
"""
Object for encapsulating process execution by using callbacks for stdout,
stderr and stdin.
"""
__docformat__ = "restructuredtext en"
#-------------------------------------------------------------------------------
# Copyright (C) 2008 The IPython Development Team
#
# Distributed under the terms of the BSD License. The full license is in
# the file COPYING, distributed as part of this software.
#-------------------------------------------------------------------------------
#-------------------------------------------------------------------------------
# Imports
#-------------------------------------------------------------------------------
from killableprocess import Popen, PIPE
from threading import Thread
from time import sleep
import os
class PipedProcess(Thread):
""" Class that encapsulates process execution by using callbacks for
stdout, stderr and stdin, and providing a reliable way of
killing it.
"""
def __init__(self, command_string, out_callback,
end_callback=None,):
""" command_string: the command line executed to start the
process.
out_callback: the python callable called on stdout/stderr.
end_callback: an optional callable called when the process
finishes.
These callbacks are called from a different thread as the
thread from which is started.
"""
self.command_string = command_string
self.out_callback = out_callback
self.end_callback = end_callback
Thread.__init__(self)
def run(self):
""" Start the process and hook up the callbacks.
"""
env = os.environ
env['TERM'] = 'xterm'
process = Popen(self.command_string + ' 2>&1', shell=True,
env=env,
universal_newlines=True,
stdout=PIPE, stdin=PIPE, )
self.process = process
while True:
out_char = process.stdout.read(1)
if out_char == '':
if process.poll() is not None:
# The process has finished
break
else:
# The process is not giving any interesting
# output. No use polling it immediatly.
sleep(0.1)
else:
self.out_callback(out_char)
if self.end_callback is not None:
self.end_callback()