pymin/procman.py

   1 # vim: set encoding=utf-8 et sw=4 sts=4 :
   2
   3 import os
   4 import errno
   5 import signal
   6 import subprocess
   7 import logging ; log = logging.getLogger('pymin.procman')
   8
   9 __all__ = ('ProcessManager', 'manager', 'register', 'unregister', 'call',
  10            'start', 'stop', 'kill', 'get', 'has', 'sigchild_handler')
  11
  12 class ProcessInfo:
  13     def __init__(self, name, command, callback=None, persist=False,
  14                        args=None, kw=None, max_errors=3):
  15         self.name = name
  16         self.command = command
  17         self.callback = callback
  18         if args is None: args = list()
  19         self.args = args
  20         if kw is None: kw = dict()
  21         self.kw = kw
  22         self.persist = persist
  23         self.max_errors = max_errors
  24         self.clear()
  25     def clear(self):
  26         self.dont_run = False
  27         self.signal = None
  28         self.process = None
  29         self.error_count = 0
  30         self.running = False
  31     def start(self):
  32         assert self.process is None
  33         self.restart()
  34     def restart(self):
  35         self.clear()
  36         log.debug(u'ProcessInfo.restart(): executing %s', self.command)
  37         self.process = subprocess.Popen(self.command, *self.args, **self.kw)
  38         self.running = True
  39     def stop(self):
  40         assert self.process is not None
  41         self.dont_run = True
  42         if self.signal == signal.SIGTERM or self.signal == signal.SIGKILL:
  43             # Allready stopped, kill it
  44             self.kill(signal.SIGKILL)
  45         else:
  46             # Stop it
  47             self.kill(signal.SIGTERM)
  48     def kill(self, signum):
  49         log.debug(u'ProcessInfo.kill(): killing pid %s with signal %s',
  50                       self.process.pid, signum)
  51         assert self.process is not None
  52         os.kill(self.process.pid, signum)
  53         self.signal = signum
  54     def __repr__(self):
  55         pid = None
  56         if self.process is not None:
  57             pid = self.process.pid
  58         return 'ProcessInfo(name=%s, pid=%s command=%s, persist=%s, cb=%s)' % (
  59                     self.name, pid, self.command, self.persist,
  60                     self.callback.__name__)
  61
  62 class ProcessManager:
  63
  64     def __init__(self):
  65         self.services = dict()
  66         self.namemap = dict()
  67         self.pidmap = dict()
  68         log.debug(u'ProcessManager()')
  69
  70     def register(self, name, command, callback=None, persist=False,
  71                        *args, **kw):
  72         log.debug(u'ProcessManager.register(%s, %s, %s, %s, %s, %s)',
  73                       name, command, callback, persist, args, kw)
  74         self.services[name] = ProcessInfo(name, command, callback, persist,
  75                                           args, kw)
  76
  77     def unregister(self, name):
  78         log.debug(u'ProcessManager.unregister(%s)', name)
  79         del self.services[name]
  80
  81     def _call(self, pi):
  82         pi.start()
  83         self.namemap[pi.name] = self.pidmap[pi.process.pid] = pi
  84
  85     def call(self, name, command, callback=None, persist=False, *args, **kw):
  86         log.debug(u'ProcessManager.call(%s, %s, %s, %s, %s, %s)',
  87                       name, command, callback, persist, args, kw)
  88         pi = ProcessInfo(name, command, callback, persist, args, kw)
  89         self._call(pi)
  90
  91     def start(self, name):
  92         log.debug(u'ProcessManager.start(%s)', name)
  93         assert name not in self.namemap
  94         self._call(self.services[name])
  95
  96     def stop(self, name):
  97         log.debug(u'ProcessManager.stop(%s)', name)
  98         assert name in self.namemap
  99         self.namemap[name].stop()
 100
 101     def restart(self, name):
 102         log.debug(u'ProcessManager.restart(%s)', name)
 103         if name in self.namemap:
 104             self.namemap[name].stop()
 105             self.namemap[name].wait()
 106             self.namemap[name].restart()
 107         else:
 108             self.namemap[name].start()
 109
 110     def kill(self, name, signum):
 111         log.debug(u'ProcessManager.kill(%s, %s)', name, signum)
 112         assert name in self.namemap
 113         self.namemap[name].kill(name, stop)
 114
 115     def sigchild_handler(self, signum, stack_frame=None):
 116         log.debug(u'ProcessManager.sigchild_handler(%s)', signum)
 117         try:
 118             (pid, status) = os.waitpid(-1, os.WNOHANG)
 119         except OSError, e:
 120             log.debug(u'ProcessManager.sigchild_handler(): OSError')
 121             if e.errno is errno.ECHILD:
 122                 log.debug(u'ProcessManager.sigchild_handler(): OSError ECHILD')
 123                 return
 124             raise
 125         log.debug(u'ProcessManager.sigchild_handler: pid=%s, status=%s',
 126                       pid, status)
 127         while pid:
 128             if pid in self.pidmap:
 129                 p = self.pidmap[pid]
 130                 p.process.returncode = status
 131                 if p.callback is not None:
 132                     log.debug(u'ProcessManager.sigchild_handler: '
 133                                   u'calling %s(%s)', p.callback.__name__, p)
 134                     p.callback(self, p)
 135                 if p.dont_run or not p.persist or p.error_count >= p.max_errors:
 136                     log.debug(u"ProcessManager.sigchild_handler: can't "
 137                             u'persist, dont_run=%s, persist=%s, error_cout=%s, '
 138                             u'max_errors=%s', p.dont_run, p.persist,
 139                             p.error_count, p.max_errors)
 140                     del self.namemap[p.name]
 141                     del self.pidmap[pid]
 142                     p.clear()
 143                 else:
 144                     log.debug(u'ProcessManager.sigchild_handler: persist')
 145                     if p.process.returncode == 0:
 146                         p.error_count = 0
 147                         log.debug(u'ProcessManager.sigchild_handler: '
 148                                 u'return OK, resetting error_count')
 149                     else:
 150                         p.error_count += 1
 151                         log.debug(u'ProcessManager.sigchild_handler: return'
 152                                 u'not 0, error_count + 1 = %s', p.error_count)
 153                     del self.pidmap[pid]
 154                     p.restart()
 155                     self.pidmap[p.process.pid] = p
 156             try:
 157                 (pid, status) = os.waitpid(-1, os.WNOHANG)
 158             except OSError, e:
 159                 if e.errno == errno.ECHILD:
 160                     return
 161                 raise
 162
 163     def get(self, name):
 164         if isinstance(name, basestring): # is a name
 165             if name in self.namemap:
 166                 return self.namemap[name]
 167             if name in self.services:
 168                 return self.services[name]
 169         else: # is a pid
 170             if name in self.pidmap:
 171                 return self.pidmap[name]
 172         raise KeyError, name
 173
 174     def has(self, name):
 175         if isinstance(name, basestring): # is a name
 176             if name in self.namemap:
 177                 return True
 178             if name in self.services:
 179                 return True
 180         else: # is a pid
 181             if name in self.pidmap:
 182                 return True
 183         return False
 184
 185     def __getitem__(self, name):
 186         return self.get(name)
 187
 188     def __contains__(self, name):
 189         return self.has(name)
 190
 191
 192 if __name__ == '__main__':
 193     logging.basicConfig(
 194         level   = logging.DEBUG,
 195         format  = '%(asctime)s %(levelname)-8s %(message)s',
 196         datefmt = '%H:%M:%S',
 197     )
 198
 199
 200 # Globals
 201 manager = ProcessManager()
 202 register = manager.register
 203 unregister = manager.unregister
 204 call = manager.call
 205 start = manager.start
 206 stop = manager.stop
 207 kill = manager.kill
 208 get = manager.get
 209 has = manager.has
 210 sigchild_handler = manager.sigchild_handler
 211
 212
 213 if __name__ == '__main__':
 214
 215     import signal
 216     import time
 217
 218     sig = None
 219     count = 0
 220
 221     def SIGCHLD_handler(signum, stacktrace):
 222         global sig
 223         sig = signum
 224         print 'SIGCHLD', signum
 225
 226     def notify(pm, pi):
 227         global count
 228         if pi.name == 'test-service':
 229             print 'test-service count =', count
 230             count += 1
 231             if count > 4:
 232                 print 'test-service not persistent anymore, start test2'
 233                 pi.persist = False
 234                 pm.start('test2')
 235         print 'died:', pi.name, pi.command
 236
 237     register('test-service', ('sleep', '2'), notify, True)
 238     register('test2', ('sleep', '3'), notify, False)
 239
 240     signal.signal(signal.SIGCHLD, SIGCHLD_handler)
 241
 242     call('test', ('sleep', '5'), notify)
 243     start('test-service')
 244
 245     print "Esperando...", [pi.name for pi in manager.namemap.values()]
 246     while manager.pidmap:
 247         signal.pause()
 248         if sig == signal.SIGCHLD:
 249             sigchild_handler(sig)
 250             sig = None
 251         print "Esperando...", [pi.name for pi in manager.namemap.values()]
 252