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', 'restart', 'kill', 'get', 'has', 'sigchild_handler')
  11
  12 class ProcessInfo:
  13     def __init__(self, name, command, callback=None, persist=False,
  14                  max_errors=3, args=None, kwargs=None):
  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 kwargs is None: kwargs = dict()
  21         self.kwargs = kwargs
  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     def start(self):
  31         assert self.process is None
  32         self.restart()
  33     def restart(self):
  34         self.clear()
  35         log.debug(u'ProcessInfo.restart(): executing %s', self.command)
  36         self.process = subprocess.Popen(self.command, *self.args, **self.kwargs)
  37     def stop(self):
  38         assert self.process is not None
  39         self.dont_run = True
  40         if self.signal == signal.SIGTERM or self.signal == signal.SIGKILL:
  41             # Allready stopped, kill it
  42             self.kill(signal.SIGKILL)
  43         else:
  44             # Stop it
  45             self.kill(signal.SIGTERM)
  46     def kill(self, signum):
  47         log.debug(u'ProcessInfo.kill(): killing pid %s with signal %s',
  48                       self.process.pid, signum)
  49         assert self.process is not None
  50         os.kill(self.process.pid, signum)
  51         self.signal = signum
  52     @property
  53     def running(self):
  54         return self.process is not None and self.process.poll() is None
  55     def __repr__(self):
  56         pid = None
  57         if self.process is not None:
  58             pid = self.process.pid
  59         return 'ProcessInfo(name=%s, pid=%s command=%s, persist=%s, cb=%s)' % (
  60                     self.name, pid, self.command, self.persist,
  61                     self.callback.__name__)
  62
  63 class ProcessManager:
  64
  65     def __init__(self):
  66         self.services = dict()
  67         self.namemap = dict()
  68         self.pidmap = dict()
  69         log.debug(u'ProcessManager()')
  70
  71     def register(self, name, command, callback=None, persist=False,
  72                 max_errors=3, *args, **kwargs):
  73         log.debug(u'ProcessManager.register(%s, %s, %s, %s, %s, %s, %s)',
  74                   name, command, callback, persist, max_errors, args, kwargs)
  75         self.services[name] = ProcessInfo(name, command, callback, persist,
  76                                           max_errors, args, kwargs)
  77
  78     def unregister(self, name):
  79         log.debug(u'ProcessManager.unregister(%s)', name)
  80         del self.services[name]
  81
  82     def _call(self, pi):
  83         pi.start()
  84         self.namemap[pi.name] = self.pidmap[pi.process.pid] = pi
  85
  86     def call(self, name, command, callback=None, persist=False,
  87                 max_errors=3, *args, **kwargs):
  88         log.debug(u'ProcessManager.call(%s, %s, %s, %s, %s, %s, %s)',
  89                   name, command, callback, persist, max_errors, args, kwargs)
  90         pi = ProcessInfo(name, command, callback, persist, max_errors,
  91                          args, kwargs)
  92         self._call(pi)
  93
  94     def start(self, name):
  95         log.debug(u'ProcessManager.start(%s)', name)
  96         assert name not in self.namemap
  97         self._call(self.services[name])
  98
  99     def stop(self, name):
 100         log.debug(u'ProcessManager.stop(%s)', name)
 101         assert name in self.namemap
 102         self.namemap[name].stop()
 103
 104     def restart(self, name):
 105         log.debug(u'ProcessManager.restart(%s)', name)
 106         # we have to check first in namemap in case is an unregistered
 107         # process (added with call())
 108         if name in self.namemap:
 109             pi = self.namemap[name]
 110             pi.stop()
 111             pi.process.wait()
 112             pi.restart()
 113         else:
 114             self.services[name].start()
 115
 116     def kill(self, name, signum):
 117         log.debug(u'ProcessManager.kill(%s, %s)', name, signum)
 118         assert name in self.namemap
 119         self.namemap[name].kill(name, stop)
 120
 121     def sigchild_handler(self, signum, stack_frame=None):
 122         log.debug(u'ProcessManager.sigchild_handler(%s)', signum)
 123         try:
 124             (pid, status) = os.waitpid(-1, os.WNOHANG)
 125         except OSError, e:
 126             log.debug(u'ProcessManager.sigchild_handler(): OSError')
 127             if e.errno is errno.ECHILD:
 128                 log.debug(u'ProcessManager.sigchild_handler(): OSError ECHILD')
 129                 return
 130             raise
 131         log.debug(u'ProcessManager.sigchild_handler: pid=%s, status=%s',
 132                       pid, status)
 133         while pid:
 134             if pid in self.pidmap:
 135                 p = self.pidmap[pid]
 136                 p.process.returncode = status
 137                 if p.callback is not None:
 138                     log.debug(u'ProcessManager.sigchild_handler: '
 139                                   u'calling %s(%s)', p.callback.__name__, p)
 140                     p.callback(self, p)
 141                 if p.dont_run or not p.persist or p.error_count >= p.max_errors:
 142                     log.debug(u"ProcessManager.sigchild_handler: can't "
 143                             u'persist, dont_run=%s, persist=%s, error_cout=%s, '
 144                             u'max_errors=%s', p.dont_run, p.persist,
 145                             p.error_count, p.max_errors)
 146                     del self.namemap[p.name]
 147                     del self.pidmap[pid]
 148                     p.clear()
 149                 else:
 150                     log.debug(u'ProcessManager.sigchild_handler: persist')
 151                     if p.process.returncode == 0:
 152                         p.error_count = 0
 153                         log.debug(u'ProcessManager.sigchild_handler: '
 154                                 u'return OK, resetting error_count')
 155                     else:
 156                         p.error_count += 1
 157                         log.debug(u'ProcessManager.sigchild_handler: return'
 158                                 u'not 0, error_count + 1 = %s', p.error_count)
 159                     del self.pidmap[pid]
 160                     p.restart()
 161                     self.pidmap[p.process.pid] = p
 162             try:
 163                 (pid, status) = os.waitpid(-1, os.WNOHANG)
 164             except OSError, e:
 165                 if e.errno == errno.ECHILD:
 166                     return
 167                 raise
 168
 169     def get(self, name):
 170         if isinstance(name, basestring): # is a name
 171             if name in self.namemap:
 172                 return self.namemap[name]
 173             if name in self.services:
 174                 return self.services[name]
 175         else: # is a pid
 176             if name in self.pidmap:
 177                 return self.pidmap[name]
 178         raise KeyError, name
 179
 180     def has(self, name):
 181         if isinstance(name, basestring): # is a name
 182             if name in self.namemap:
 183                 return True
 184             if name in self.services:
 185                 return True
 186         else: # is a pid
 187             if name in self.pidmap:
 188                 return True
 189         return False
 190
 191     def __getitem__(self, name):
 192         return self.get(name)
 193
 194     def __contains__(self, name):
 195         return self.has(name)
 196
 197
 198 if __name__ == '__main__':
 199     logging.basicConfig(
 200         level   = logging.DEBUG,
 201         format  = '%(asctime)s %(levelname)-8s %(message)s',
 202         datefmt = '%H:%M:%S',
 203     )
 204
 205
 206 # Globals
 207 manager = ProcessManager()
 208 register = manager.register
 209 unregister = manager.unregister
 210 call = manager.call
 211 start = manager.start
 212 stop = manager.stop
 213 restart = manager.restart
 214 kill = manager.kill
 215 get = manager.get
 216 has = manager.has
 217 sigchild_handler = manager.sigchild_handler
 218
 219
 220 if __name__ == '__main__':
 221
 222     import signal
 223     import time
 224
 225     sig = None
 226     count = 0
 227
 228     def SIGCHLD_handler(signum, stacktrace):
 229         global sig
 230         sig = signum
 231         print 'SIGCHLD', signum
 232
 233     def notify(pm, pi):
 234         global count
 235         if pi.name == 'test-service':
 236             print 'test-service count =', count
 237             count += 1
 238             if count > 4:
 239                 print 'set test-service non-persistent, start test-service-2'
 240                 pi.persist = False
 241                 assert 'test-service-2' not in manager.namemap
 242                 pm.start('test-service-2')
 243                 assert 'test-service-2' in manager.namemap
 244                 assert get('test-service-2').running
 245         print 'died:', pi.name, pi.command
 246
 247     register('test-service', ('sleep', '2'), notify, True)
 248     assert 'test-service' in manager.services
 249     assert 'test-service' not in manager.namemap
 250     assert not get('test-service').running
 251
 252     register('test-service-2', ('sleep', '3'), notify, False)
 253     assert 'test-service-2' in manager.services
 254     assert 'test-service-2' not in manager.namemap
 255     assert not get('test-service-2').running
 256
 257     signal.signal(signal.SIGCHLD, SIGCHLD_handler)
 258
 259     call('test-once', ('sleep', '5'), notify)
 260     assert 'test-once' not in manager.services
 261     assert 'test-once' in manager.namemap
 262     assert get('test-once').running
 263
 264     start('test-service')
 265     assert 'test-service' in manager.namemap
 266     assert get('test-service').running
 267
 268     print "Known processes:", manager.services.keys()
 269     print "Waiting...", manager.namemap.keys()
 270     print "------------------------------------------------------------------"
 271     while manager.pidmap:
 272         signal.pause()
 273         if sig == signal.SIGCHLD:
 274             sigchild_handler(sig)
 275             sig = None
 276         print "Known processes:", manager.services.keys()
 277         print "Waiting...", manager.namemap.keys()
 278         print "------------------------------------------------------------------"
 279     assert 'test-service' not in manager.namemap
 280     assert 'test-service-2' not in manager.namemap
 281     assert 'test-once' not in manager.services
 282     assert 'test-once' not in manager.namemap
 283
 284     call('test-wait', ('sleep', '2'))
 285     print 'test-wait returned?', get('test-wait').process.poll()
 286     assert get('test-wait').running
 287     print 'Waiting test-wait to return...'
 288     ret = get('test-wait').process.wait()
 289     print 'Done! returned:', ret
 290