# # Copyright CEA/DAM/DIF (2007, 2008, 2009, 2010, 2011) # Contributor: Stephane THIELL # # This file is part of the ClusterShell library. # # This software is governed by the CeCILL-C license under French law and # abiding by the rules of distribution of free software. You can use, # modify and/ or redistribute the software under the terms of the CeCILL-C # license as circulated by CEA, CNRS and INRIA at the following URL # "http://www.cecill.info". # # As a counterpart to the access to the source code and rights to copy, # modify and redistribute granted by the license, users are provided only # with a limited warranty and the software's author, the holder of the # economic rights, and the successive licensors have only limited # liability. # # In this respect, the user's attention is drawn to the risks associated # with loading, using, modifying and/or developing or reproducing the # software by the user in light of its specific status of free software, # that may mean that it is complicated to manipulate, and that also # therefore means that it is reserved for developers and experienced # professionals having in-depth computer knowledge. Users are therefore # encouraged to load and test the software's suitability as regards their # requirements in conditions enabling the security of their systems and/or # data to be ensured and, more generally, to use and operate it in the # same conditions as regards security. # # The fact that you are presently reading this means that you have had # knowledge of the CeCILL-C license and that you accept its terms. """ A poll() based ClusterShell Engine. The poll() system call is available on Linux and BSD. """ import errno import os import select import sys import time from ClusterShell.Engine.Engine import Engine from ClusterShell.Engine.Engine import EngineException from ClusterShell.Engine.Engine import EngineNotSupportedError from ClusterShell.Engine.Engine import EngineTimeoutException from ClusterShell.Worker.EngineClient import EngineClientEOF class EnginePoll(Engine): """ Poll Engine ClusterShell engine using the select.poll mechanism (Linux poll() syscall). """ identifier = "poll" def __init__(self, info): """ Initialize Engine. """ Engine.__init__(self, info) try: # get a polling object self.polling = select.poll() except AttributeError: raise EngineNotSupportedError(EnginePoll.identifier) def _register_specific(self, fd, event): if event & (Engine.E_READ | Engine.E_ERROR): eventmask = select.POLLIN elif event == Engine.E_WRITE: eventmask = select.POLLOUT self.polling.register(fd, eventmask) def _unregister_specific(self, fd, ev_is_set): if ev_is_set: self.polling.unregister(fd) def _modify_specific(self, fd, event, setvalue): """ Engine-specific modifications after a interesting event change for a file descriptor. Called automatically by Engine register/unregister and set_events(). For the poll() engine, it reg/unreg or modifies the event mask associated to a file descriptor. """ self._debug("MODSPEC fd=%d event=%x setvalue=%d" % (fd, event, setvalue)) if setvalue: eventmask = 0 if event & (Engine.E_READ | Engine.E_ERROR): eventmask = select.POLLIN elif event == Engine.E_WRITE: eventmask = select.POLLOUT self.polling.register(fd, eventmask) else: self.polling.unregister(fd) def runloop(self, timeout): """ Poll engine run(): start clients and properly get replies """ if timeout == 0: timeout = -1 start_time = time.time() # run main event loop... while self.evlooprefcnt > 0: self._debug("LOOP evlooprefcnt=%d (reg_clifds=%s) (timers=%d)" \ % (self.evlooprefcnt, self.reg_clifds.keys(), \ len(self.timerq))) try: timeo = self.timerq.nextfire_delay() if timeout > 0 and timeo >= timeout: # task timeout may invalidate clients timeout self.timerq.clear() timeo = timeout elif timeo == -1: timeo = timeout self._current_loopcnt += 1 evlist = self.polling.poll(timeo * 1000.0 + 1.0) except select.error, (ex_errno, ex_strerror): # might get interrupted by a signal if ex_errno == errno.EINTR: continue elif ex_errno == errno.EINVAL: print >> sys.stderr, \ "EnginePoll: please increase RLIMIT_NOFILE" raise for fd, event in evlist: if event & select.POLLNVAL: raise EngineException("Caught POLLNVAL on fd %d" % fd) # get client instance client, fdev = self._fd2client(fd) if client is None: continue # process this client client._current_client = client # check for poll error condition of some sort if event & select.POLLERR: self._debug("POLLERR %s" % client) self.unregister_writer(client) os.close(client.fd_writer) client.fd_writer = None client._current_client = None continue # check for data to read if event & select.POLLIN: assert fdev & (Engine.E_READ | Engine.E_ERROR) assert client._events & fdev self.modify(client, 0, fdev) try: if fdev & Engine.E_READ: client._handle_read() else: client._handle_error() except EngineClientEOF: self._debug("EngineClientEOF %s" % client) if fdev & Engine.E_READ: self.remove(client) client._current_client = None continue # or check for end of stream (do not handle both at the same # time because handle_read() may perform a partial read) elif event & select.POLLHUP: self._debug("POLLHUP fd=%d %s (r%s,e%s,w%s)" % (fd, client.__class__.__name__, client.fd_reader, client.fd_error, client.fd_writer)) if fdev & Engine.E_READ: if client._events & Engine.E_ERROR: self.modify(client, 0, fdev) else: self.remove(client) else: if client._events & Engine.E_READ: self.modify(client, 0, fdev) else: self.remove(client) # check for writing if event & select.POLLOUT: self._debug("POLLOUT fd=%d %s (r%s,e%s,w%s)" % (fd, client.__class__.__name__, client.fd_reader, client.fd_error, client.fd_writer)) assert fdev == Engine.E_WRITE assert client._events & fdev self.modify(client, 0, fdev) client._handle_write() client._current_client = None # apply any changes occured during processing if client.registered: self.set_events(client, client._new_events) # check for task runloop timeout if timeout > 0 and time.time() >= start_time + timeout: raise EngineTimeoutException() # process clients timeout self.fire_timers() self._debug("LOOP EXIT evlooprefcnt=%d (reg_clifds=%s) (timers=%d)" % \ (self.evlooprefcnt, self.reg_clifds, len(self.timerq)))