JezK
Edit File: process.py
# # Module providing the `Process` class which emulates `threading.Thread` # # multiprocessing/process.py # # Copyright (c) 2006-2008, R Oudkerk # All rights reserved. # # Redistribution and use in source and binary forms, with or without # modification, are permitted provided that the following conditions # are met: # # 1. Redistributions of source code must retain the above copyright # notice, this list of conditions and the following disclaimer. # 2. Redistributions in binary form must reproduce the above copyright # notice, this list of conditions and the following disclaimer in the # documentation and/or other materials provided with the distribution. # 3. Neither the name of author nor the names of any contributors may be # used to endorse or promote products derived from this software # without specific prior written permission. # # THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS "AS IS" AND # ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE # IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE # ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE # FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL # DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS # OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) # HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT # LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY # OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF # SUCH DAMAGE. # __all__ = ['Process', 'current_process', 'active_children'] # # Imports # import os import sys import signal import itertools # # # try: ORIGINAL_DIR = os.path.abspath(os.getcwd()) except OSError: ORIGINAL_DIR = None # # Public functions # def current_process(): ''' Return process object representing the current process ''' return _current_process def active_children(): ''' Return list of process objects corresponding to live child processes ''' _cleanup() return list(_current_process._children) # # # def _cleanup(): # check for processes which have finished for p in list(_current_process._children): if p._popen.poll() is not None: _current_process._children.discard(p) # # The `Process` class # class Process(object): ''' Process objects represent activity that is run in a separate process The class is analagous to `threading.Thread` ''' _Popen = None def __init__(self, group=None, target=None, name=None, args=(), kwargs={}): assert group is None, 'group argument must be None for now' count = _current_process._counter.next() self._identity = _current_process._identity + (count,) self._authkey = _current_process._authkey self._daemonic = _current_process._daemonic self._tempdir = _current_process._tempdir self._parent_pid = os.getpid() self._popen = None self._target = target self._args = tuple(args) self._kwargs = dict(kwargs) self._name = name or type(self).__name__ + '-' + \ ':'.join(str(i) for i in self._identity) def run(self): ''' Method to be run in sub-process; can be overridden in sub-class ''' if self._target: self._target(*self._args, **self._kwargs) def start(self): ''' Start child process ''' assert self._popen is None, 'cannot start a process twice' assert self._parent_pid == os.getpid(), \ 'can only start a process object created by current process' assert not _current_process._daemonic, \ 'daemonic processes are not allowed to have children' _cleanup() if self._Popen is not None: Popen = self._Popen else: from .forking import Popen self._popen = Popen(self) # Avoid a refcycle if the target function holds an indirect # reference to the process object (see bpo-30775) del self._target, self._args, self._kwargs _current_process._children.add(self) def terminate(self): ''' Terminate process; sends SIGTERM signal or uses TerminateProcess() ''' self._popen.terminate() def join(self, timeout=None): ''' Wait until child process terminates ''' assert self._parent_pid == os.getpid(), 'can only join a child process' assert self._popen is not None, 'can only join a started process' res = self._popen.wait(timeout) if res is not None: _current_process._children.discard(self) def is_alive(self): ''' Return whether process is alive ''' if self is _current_process: return True assert self._parent_pid == os.getpid(), 'can only test a child process' if self._popen is None: return False returncode = self._popen.poll() if returncode is None: return True else: _current_process._children.discard(self) return False @property def name(self): return self._name @name.setter def name(self, name): assert isinstance(name, basestring), 'name must be a string' self._name = name @property def daemon(self): ''' Return whether process is a daemon ''' return self._daemonic @daemon.setter def daemon(self, daemonic): ''' Set whether process is a daemon ''' assert self._popen is None, 'process has already started' self._daemonic = daemonic @property def authkey(self): return self._authkey @authkey.setter def authkey(self, authkey): ''' Set authorization key of process ''' self._authkey = AuthenticationString(authkey) @property def exitcode(self): ''' Return exit code of process or `None` if it has yet to stop ''' if self._popen is None: return self._popen return self._popen.poll() @property def ident(self): ''' Return identifier (PID) of process or `None` if it has yet to start ''' if self is _current_process: return os.getpid() else: return self._popen and self._popen.pid pid = ident def __repr__(self): if self is _current_process: status = 'started' elif self._parent_pid != os.getpid(): status = 'unknown' elif self._popen is None: status = 'initial' else: if self._popen.poll() is not None: status = self.exitcode else: status = 'started' if type(status) in (int, long): if status == 0: status = 'stopped' else: status = 'stopped[%s]' % _exitcode_to_name.get(status, status) return '<%s(%s, %s%s)>' % (type(self).__name__, self._name, status, self._daemonic and ' daemon' or '') ## def _bootstrap(self): from . import util global _current_process try: self._children = set() self._counter = itertools.count(1) try: sys.stdin.close() sys.stdin = open(os.devnull) except (OSError, ValueError): pass _current_process = self util._finalizer_registry.clear() util._run_after_forkers() util.info('child process calling self.run()') try: self.run() exitcode = 0 finally: util._exit_function() except SystemExit, e: if not e.args: exitcode = 1 elif isinstance(e.args[0], (int, long)): exitcode = int(e.args[0]) else: sys.stderr.write(str(e.args[0]) + '\n') sys.stderr.flush() exitcode = 1 except: exitcode = 1 import traceback sys.stderr.write('Process %s:\n' % self.name) sys.stderr.flush() traceback.print_exc() util.info('process exiting with exitcode %d' % exitcode) return exitcode # # We subclass bytes to avoid accidental transmission of auth keys over network # class AuthenticationString(bytes): def __reduce__(self): from .forking import Popen if not Popen.thread_is_spawning(): raise TypeError( 'Pickling an AuthenticationString object is ' 'disallowed for security reasons' ) return AuthenticationString, (bytes(self),) # # Create object representing the main process # class _MainProcess(Process): def __init__(self): self._identity = () self._daemonic = False self._name = 'MainProcess' self._parent_pid = None self._popen = None self._counter = itertools.count(1) self._children = set() self._authkey = AuthenticationString(os.urandom(32)) self._tempdir = None _current_process = _MainProcess() del _MainProcess # # Give names to some return codes # _exitcode_to_name = {} for name, signum in signal.__dict__.items(): if name[:3]=='SIG' and '_' not in name: _exitcode_to_name[-signum] = name