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