Source Code for Module ClusterShell.Worker.Popen

  1  # 
  2  # Copyright (C) 2008-2015 CEA/DAM 
  3  # Copyright (C) 2015 Stephane Thiell <sthiell@stanford.edu> 
  4  # 
  5  # This file is part of ClusterShell. 
  6  # 
  7  # ClusterShell is free software; you can redistribute it and/or 
  8  # modify it under the terms of the GNU Lesser General Public 
  9  # License as published by the Free Software Foundation; either 
 10  # version 2.1 of the License, or (at your option) any later version. 
 11  # 
 12  # ClusterShell is distributed in the hope that it will be useful, 
 13  # but WITHOUT ANY WARRANTY; without even the implied warranty of 
 14  # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU 
 15  # Lesser General Public License for more details. 
 16  # 
 17  # You should have received a copy of the GNU Lesser General Public 
 18  # License along with ClusterShell; if not, write to the Free Software 
 19  # Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 
 20   
 21  """ 
 22  WorkerPopen 
 23   
 24  ClusterShell worker for executing local commands. 
 25   
 26  Usage example: 
 27     >>> worker = WorkerPopen("/bin/uname", key="mykernel") 
 28     >>> task.schedule(worker)    # schedule worker 
 29     >>> task.resume()            # run task 
 30     >>> worker.retcode()         # get return code 
 31     0 
 32     >>> worker.read()            # read command output 
 33     'Linux' 
 34   
 35  """ 
 36   
 37  from ClusterShell.Worker.Worker import WorkerSimple, StreamClient 
 38   
 39   
 40 -class PopenClient(StreamClient): 
 41   
 42 -    def __init__(self, worker, key, stderr, timeout, autoclose): 
 43          StreamClient.__init__(self, worker, key, stderr, timeout, autoclose) 
 44          self.popen = None 
 45          self.rc = None 
 46          # Declare writer stream to allow early buffering 
 47          self.streams.set_writer(worker.SNAME_STDIN, None, retain=False) 
 48   
 49 -    def _start(self): 
 50          """Worker is starting.""" 
 51          assert not self.worker.started 
 52          assert self.popen is None 
 53   
 54          self.popen = self._exec_nonblock(self.worker.command, shell=True) 
 55   
 56          task = self.worker.task 
 57          if task.info("debug", False): 
 58              task.info("print_debug")(task, "POPEN: %s" % self.worker.command) 
 59   
 60          self.worker._on_start(self.key) 
 61          return self 
 62   
 63 -    def _close(self, abort, timeout): 
 64          """ 
 65          Close client. See EngineClient._close(). 
 66          """ 
 67          if abort: 
 68              # it's safer to call poll() first for long time completed processes 
 69              prc = self.popen.poll() 
 70              # if prc is None, process is still running 
 71              if prc is None: 
 72                  try: # try to kill it 
 73                      self.popen.kill() 
 74                  except OSError: 
 75                      pass 
 76          prc = self.popen.wait() 
 77   
 78          self.streams.clear() 
 79   
 80          if prc >= 0: # filter valid rc 
 81              self.rc = prc 
 82              self.worker._on_rc(self.key, prc) 
 83          elif timeout: 
 84              assert abort, "abort flag not set on timeout" 
 85              self.worker._on_timeout(self.key) 
 86          elif not abort: 
 87              # if process was signaled, return 128 + signum (bash-like) 
 88              self.rc = 128 + -prc 
 89              self.worker._on_rc(self.key, self.rc) 
 90   
 91          if self.worker.eh: 
 92              self.worker.eh.ev_close(self.worker) 
 93   
 94   
 95 -class WorkerPopen(WorkerSimple): 
 96      """ 
 97      Implements the Popen Worker. 
 98      """ 
 99 -    def __init__(self, command, key=None, handler=None, 
100                   stderr=False, timeout=-1, autoclose=False): 
101          """Initialize Popen worker.""" 
102          WorkerSimple.__init__(self, None, None, None, key, handler, stderr, 
103                                timeout, autoclose, client_class=PopenClient) 
104          self.command = command 
105          if not self.command: 
106              raise ValueError("missing command parameter in WorkerPopen " 
107                               "constructor") 
108   
109 -    def retcode(self): 
110          """Return return code or None if command is still in progress.""" 
111          return self.clients[0].rc 
112   
113  WORKER_CLASS = WorkerPopen 
114