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