Source Code for Module Proxy.Task

  1  # Copyright (C) 2005, 2006 Joint Institute for VLBI in Europe 
  2  # 
  3  # This program is free software; you can redistribute it and/or modify 
  4  # it under the terms of the GNU General Public License as published by 
  5  # the Free Software Foundation; either version 2 of the License, or 
  6  # (at your option) any later version. 
  7  # 
  8  # This program is distributed in the hope that it will be useful, 
  9  # but WITHOUT ANY WARRANTY; without even the implied warranty of 
 10  # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 
 11  # GNU General Public License for more details. 
 12   
 13  # You should have received a copy of the GNU General Public License 
 14  # along with this program; if not, write to the Free Software 
 15  # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA 
 16   
 17  """ 
 18   
 19  This module provides bits and pieces to implement generic Task proxy 
 20  objects. 
 21   
 22  """ 
 23   
 24  # Generic Python stuff. 
 25  import fcntl, os, pty, select, signal 
 26   
 27 -class Task: 
 28 -    def __init__(self): 
 29          self._pid = {} 
 30   
 31 -    def spawn(self, path, args, env=None): 
 32          """Start the task.""" 
 33   
 34          (pid, tid) = pty.fork() 
 35          if pid == 0: 
 36              try: 
 37                  if env: 
 38                      os.execve(path, args, env) 
 39                  else: 
 40                      os.execv(path, args) 
 41              finally: 
 42                  os._exit(1) 
 43          else: 
 44              fcntl.fcntl(tid, fcntl.F_SETFL, os.O_NONBLOCK) 
 45              self._pid[tid] = pid 
 46              return tid 
 47   
 48 -    def finished(self, tid): 
 49          """Check whether the task has finished.""" 
 50          return self._pid[tid] == 0 
 51   
 52 -    def messages(self, tid): 
 53          """Return task's messages.""" 
 54   
 55          (iwtd, owtd, ewtd) = select.select([tid], [], [], 0.25) 
 56          if tid in iwtd: 
 57              try: 
 58                  messages = os.read(tid, 1024) 
 59                  if len(messages) > 0: 
 60                      messages = messages.split('\r\n') 
 61                      return [msg for msg in messages if msg] 
 62              except: 
 63                  pass 
 64   
 65              pass 
 66   
 67          # If reading failed, it's (probably) because the child 
 68          # process died. 
 69          (pid, status) = os.waitpid(self._pid[tid], os.WNOHANG) 
 70          if pid: 
 71              assert(pid == self._pid[tid]) 
 72              if os.WIFEXITED(status) or os.WIFSIGNALED(status): 
 73                  self._pid[tid] = 0 
 74          return [] 
 75   
 76 -    def feed(self, tid, banana): 
 77          """Feed the task.""" 
 78   
 79          os.write(tid, banana) 
 80          pass 
 81   
 82 -    def wait(self, tid): 
 83          """Wait for the task to finish.""" 
 84   
 85          assert(self.finished(tid)) 
 86   
 87          del self._pid[tid] 
 88          os.close(tid) 
 89          return 
 90   
 91 -    def abort(self, tid, sig=signal.SIGINT): 
 92          """Abort a task.""" 
 93   
 94          os.kill (self._pid[tid], sig) 
 95   
 96          del self._pid[tid] 
 97          os.close(tid) 
 98          return 
 99