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  2. """Generic linux daemon base class for python 3.x."""
  3. import uuid
  4. import sys
  5. import os
  6. import time
  7. import threading
  10. class daemon(object):
  11. """A generic daemon class.
  13. Usage: subclass the daemon class and override the run() method."""
  15. def __init__(self):
  16. self._thread = threading.Thread(target=self.test, name='task_queue', daemon=True)
  18. def test(self):
  19. for i in range(3):
  20. print('running loop %s' % i)
  21. time.sleep(1)
  23. def daemonize(self):
  24. """Daemonizes the current process. Returns the new pid"""
  25. try:
  26. pid = os.fork()
  27. if pid > 0:
  28. # exit first parent
  29. sys.exit(0)
  30. except OSError as err:
  31. sys.stderr.write('fork #1 failed: {0}\n'.format(err))
  32. sys.exit(1)
  34. # decouple from parent environment
  35. os.chdir('/')
  36. os.setsid()
  37. os.umask(0)
  39. print('First fork pid %s' % os.getpid())
  41. # do second fork
  42. try:
  43. pid = os.fork()
  44. if pid > 0:
  45. # exit from second parent
  46. sys.exit(0)
  47. except OSError as err:
  48. sys.stderr.write('fork #2 failed: {0}\n'.format(err))
  49. sys.exit(1)
  51. # redirect standard file descriptors
  52. sys.stdout.flush()
  53. sys.stderr.flush()
  54. si = open(os.devnull, 'r')
  55. so = open('/tmp/file', 'a+')
  56. se = open('/tmp/file', 'a+')
  58. os.dup2(si.fileno(), sys.stdin.fileno())
  59. os.dup2(so.fileno(), sys.stdout.fileno())
  60. os.dup2(se.fileno(), sys.stderr.fileno())
  62. def start(self):
  63. """Start the daemon."""
  64. # Start the daemon
  65. self.daemonize()
  66. self._thread.start()
  67. self.wait()
  69. def wait(self):
  70. """
  71. Waits for the thread to exit.
  72. Allows abortion of task queue with ctrl-c
  73. """
  74. try:
  75. print('thread alive is %s' % self._thread.is_alive())
  76. while self._thread.is_alive():
  77. print('pid %s wait sleep thread alive is %s' % (os.getpid(), self._thread.is_alive()))
  78. time.sleep(0.5)
  79. except KeyboardInterrupt:
  80. print('Got ctrl-c, shutting down after running task (if any) completes')
  81. # We still wait to finish cleanly, pressing ctrl-c again will abort
  82. while self._thread.is_alive():
  83. time.sleep(0.5)
  85. d = daemon()
  86. d.start()
  87.  
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