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