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', 'once',
  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,
  37                                          *self.args, **self.kwargs)
  38     def stop(self):
  39         assert self.process is not None
  40         self._dont_run = True
  41         if self._signal == signal.SIGTERM or self._signal == signal.SIGKILL:
  42             # Allready stopped, kill it
  43             self.kill(signal.SIGKILL)
  44         else:
  45             # Stop it
  46             self.kill(signal.SIGTERM)
  47     def kill(self, signum):
  48         log.debug(u'ProcessInfo.kill(): killing pid %s with signal %s',
  49                       self.process.pid, signum)
  50         assert self.process is not None
  51         os.kill(self.process.pid, signum)
  52         self._signal = signum
  53     @property
  54     def running(self):
  55         return self.process is not None and self.process.poll() is None
  56     @property
  57     def name(self):
  58         return self._name
  59     @property
  60     def process(self):
  61         return self._process
  62     @property
  63     def error_count(self):
  64         return self._error_count
  65     def __repr__(self):
  66         pid = None
  67         if self.process is not None:
  68             pid = self.process.pid
  69         return 'ProcessInfo(name=%s, pid=%s command=%s, persist=%s, cb=%s)' % (
  70                     self.name, pid, self.command, self.persist,
  71                     self.callback and self.callback.__name__ or None)
  72
  73 class ProcessManager:
  74
  75     def __init__(self):
  76         self.services = dict()
  77         self.namemap = dict()
  78         self.pidmap = dict()
  79         log.debug(u'ProcessManager()')
  80
  81     def register(self, name, command=None, callback=None, persist=False,
  82                 max_errors=3, *args, **kwargs):
  83         log.debug(u'ProcessManager.register(%s, %s, %s, %s, %s, %s, %s)',
  84                   name, command, callback, persist, max_errors, args, kwargs)
  85         if not isinstance(name, ProcessInfo):
  86             pi = ProcessInfo(name, command, callback, persist, max_errors,
  87                              args, kwargs)
  88         else:
  89             pi = name
  90             name = pi.name
  91         assert not self.has(name)
  92         self.services[name] = pi
  93         return pi
  94
  95     def unregister(self, name):
  96         log.debug(u'ProcessManager.unregister(%s)', name)
  97         if isinstance(name, ProcessInfo):
  98             pi = name
  99             name = pi.name
 100         else:
 101             pi = self.services[name]
 102         del self.services[name]
 103         return pi
 104
 105     def _call(self, pi):
 106         pi.start()
 107         self.namemap[pi.name] = self.pidmap[pi.process.pid] = pi
 108
 109     def once(self, name, command=None, callback=None, persist=False,
 110                 max_errors=3, *args, **kwargs):
 111         log.debug(u'ProcessManager.once(%s, %s, %s, %s, %s, %s, %s)',
 112                   name, command, callback, persist, max_errors, args, kwargs)
 113         if not isinstance(name, ProcessInfo):
 114             pi = ProcessInfo(name, command, callback, persist, max_errors,
 115                              args, kwargs)
 116         else:
 117             pi = name
 118             name = pi.name
 119         assert not self.has(name)
 120         self._call(pi)
 121         return pi
 122
 123     def start(self, name):
 124         log.debug(u'ProcessManager.start(%s)', name)
 125         if isinstance(name, ProcessInfo):
 126             name = name.name
 127         if name not in self.namemap:
 128             self._call(self.services[name])
 129             return True
 130         return False
 131
 132     def stop(self, name):
 133         log.debug(u'ProcessManager.stop(%s)', name)
 134         if isinstance(name, ProcessInfo):
 135             name = name.name
 136         if name in self.namemap:
 137             self.namemap[name].stop()
 138             return True
 139         return False
 140
 141     def restart(self, name):
 142         log.debug(u'ProcessManager.restart(%s)', name)
 143         if isinstance(name, ProcessInfo):
 144             name = name.name
 145         # we have to check first in namemap in case is an unregistered
 146         # process (added with once())
 147         if name in self.namemap:
 148             pi = self.namemap[name]
 149             # the process will change its PID, so we delete it while we know it
 150             del self.pidmap[pi.process.pid]
 151             pi.stop()
 152             pi.process.wait()
 153             pi.restart()
 154             # add the new PID
 155             self.pidmap[pi.process.pid] = pi
 156             return True
 157         else:
 158             self.start(name)
 159             return False
 160
 161     def kill(self, name, signum):
 162         log.debug(u'ProcessManager.kill(%s, %s)', name, signum)
 163         if isinstance(name, ProcessInfo):
 164             name = name.name
 165         if name in self.namemap:
 166             self.namemap[name].kill(name, stop)
 167             return True
 168         return False
 169
 170     def sigchild_handler(self, signum, stack_frame=None):
 171         log.debug(u'ProcessManager.sigchild_handler(%s)', signum)
 172         try:
 173             (pid, status) = os.waitpid(-1, os.WNOHANG)
 174         except OSError, e:
 175             log.debug(u'ProcessManager.sigchild_handler(): OSError')
 176             if e.errno is errno.ECHILD:
 177                 log.debug(u'ProcessManager.sigchild_handler(): OSError ECHILD')
 178                 return
 179             raise
 180         log.debug(u'ProcessManager.sigchild_handler: pid=%s, status=%s',
 181                       pid, status)
 182         while pid:
 183             if pid in self.pidmap:
 184                 p = self.pidmap[pid]
 185                 p.process.returncode = status
 186                 if p.callback is not None:
 187                     log.debug(u'ProcessManager.sigchild_handler: '
 188                                   u'calling %s(%s)', p.callback.__name__, p)
 189                     p.callback(self, p)
 190                 if (p._dont_run or not p.persist
 191                                 or p._error_count >= p.max_errors):
 192                     log.debug(u"ProcessManager.sigchild_handler: can't "
 193                             u'persist, dont_run=%s, persist=%s, error_cout=%s, '
 194                             u'max_errors=%s', p._dont_run, p.persist,
 195                             p._error_count, p.max_errors)
 196                     del self.namemap[p.name]
 197                     del self.pidmap[pid]
 198                     p.clear()
 199                 else:
 200                     log.debug(u'ProcessManager.sigchild_handler: persist')
 201                     if p.process.returncode == 0:
 202                         p._error_count = 0
 203                         log.debug(u'ProcessManager.sigchild_handler: '
 204                                 u'return OK, resetting error_count')
 205                     else:
 206                         p._error_count += 1
 207                         log.debug(u'ProcessManager.sigchild_handler: return'
 208                                 u'not 0, error_count + 1 = %s', p._error_count)
 209                     del self.pidmap[pid]
 210                     p.restart()
 211                     self.pidmap[p.process.pid] = p
 212             try:
 213                 (pid, status) = os.waitpid(-1, os.WNOHANG)
 214             except OSError, e:
 215                 if e.errno == errno.ECHILD:
 216                     return
 217                 raise
 218
 219     def get(self, name):
 220         if isinstance(name, basestring): # is a name
 221             if name in self.namemap:
 222                 return self.namemap[name]
 223             if name in self.services:
 224                 return self.services[name]
 225         else: # is a pid
 226             if name in self.pidmap:
 227                 return self.pidmap[name]
 228         raise KeyError, name
 229     # Syntax sugar for self[name]
 230     __getitem__ = get
 231
 232     def has(self, name):
 233         if isinstance(name, basestring): # is a name
 234             if name in self.namemap:
 235                 return True
 236             if name in self.services:
 237                 return True
 238         else: # is a pid
 239             if name in self.pidmap:
 240                 return True
 241         return False
 242     # Syntax sugar for name in self
 243     __contains__ = has
 244
 245
 246 if __name__ == '__main__':
 247     logging.basicConfig(
 248         level   = logging.DEBUG,
 249         format  = '%(asctime)s %(levelname)-8s %(message)s',
 250         datefmt = '%H:%M:%S',
 251     )
 252
 253
 254 # Globals
 255 manager = ProcessManager()
 256 register = manager.register
 257 unregister = manager.unregister
 258 once = manager.once
 259 start = manager.start
 260 stop = manager.stop
 261 restart = manager.restart
 262 kill = manager.kill
 263 get = manager.get
 264 has = manager.has
 265 sigchild_handler = manager.sigchild_handler
 266
 267
 268 if __name__ == '__main__':
 269
 270     import signal
 271     import time
 272
 273     sig = None
 274     count = 0
 275
 276     def SIGCHLD_handler(signum, stacktrace):
 277         global sig
 278         sig = signum
 279         print 'SIGCHLD', signum
 280
 281     def notify(pm, pi):
 282         global count
 283         if pi.name == 'test-service':
 284             print 'test-service count =', count
 285             count += 1
 286             if count > 4:
 287                 print 'set test-service non-persistent, start test-service-2'
 288                 pi.persist = False
 289                 assert 'test-service-2' not in manager.namemap
 290                 pm.start('test-service-2')
 291                 assert 'test-service-2' in manager.namemap
 292                 assert get('test-service-2').running
 293         print 'died:', pi.name, pi.command
 294
 295     register('test-service', ('sleep', '2'), notify, True)
 296     assert 'test-service' in manager.services
 297     assert 'test-service' not in manager.namemap
 298     assert not get('test-service').running
 299     assert manager['test-service'] == get('test-service')
 300     assert has('test-service')
 301     assert 'test-service' in manager
 302
 303     register('test-service-2', ('sleep', '3'), notify, False)
 304     assert 'test-service-2' in manager.services
 305     assert 'test-service-2' not in manager.namemap
 306     assert not get('test-service-2').running
 307
 308     signal.signal(signal.SIGCHLD, SIGCHLD_handler)
 309
 310     once('test-once', ('sleep', '5'), notify)
 311     assert 'test-once' not in manager.services
 312     assert 'test-once' in manager.namemap
 313     assert get('test-once').running
 314     assert get('test-once').process.pid
 315     pid = get('test-once').process.pid
 316     restart('test-once')
 317     assert pid != get('test-once').process.pid
 318     assert pid != manager.pidmap[get('test-once').process.pid].process.pid
 319
 320     start('test-service')
 321     assert 'test-service' in manager.namemap
 322     assert get('test-service').running
 323     assert get('test-service').process.pid
 324     pid = get('test-service').process.pid
 325     restart('test-service')
 326     assert pid != get('test-service').process.pid
 327     assert pid != manager.pidmap[get('test-service').process.pid].process.pid
 328
 329     print "Known processes:", manager.services.keys()
 330     print "Waiting...", manager.namemap.keys()
 331     print "------------------------------------------------------------------"
 332     while manager.pidmap:
 333         signal.pause()
 334         if sig == signal.SIGCHLD:
 335             sigchild_handler(sig)
 336             sig = None
 337         print "Known processes:", manager.services.keys()
 338         print "Waiting...", manager.namemap.keys()
 339         print "------------------------------------------------------------------"
 340     assert 'test-service' not in manager.namemap
 341     assert 'test-service-2' not in manager.namemap
 342     assert 'test-once' not in manager.services
 343     assert 'test-once' not in manager.namemap
 344
 345     restart('test-service')
 346     assert get('test-service').process.pid
 347     assert manager.pidmap[get('test-service').process.pid].process.pid
 348
 349     once('test-wait', ('sleep', '2'))
 350     print 'test-wait running?', get('test-wait').running
 351     assert get('test-wait').running
 352     print 'Waiting test-wait to return...'
 353     ret = get('test-wait').process.wait()
 354     print 'Done! returned:', ret
 355