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