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