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@Jd007
Created May 14, 2013 04:21

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  1. Jd007 created this gist May 14, 2013.
    132 changes: 132 additions & 0 deletions gistfile1.py
    Original file line number Diff line number Diff line change
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    import sys, os, time, atexit
    from signal import SIGTERM

    class Daemon:

    '''
    Base Daemon class that takes care of the start, stop, and forking of the processes.
    Used to daemonize any Python script.
    '''

    def __init__(self, pidfile, worker_id, stdin='/dev/null', stdout='/dev/null', stderr='/dev/null'):
    self.pidfile = pidfile
    self.worker_id = worker_id
    self.stdin = stdin
    self.stdout = stdout
    self.stderr = stderr
    self.init_time = int(time.time())
    self.successful_job_count = 0
    self.failed_job_count = 0
    self.avg_job_time = 0

    def daemonize(self):
    '''
    Double-forks the process to daemonize the script.
    '''
    try:
    pid = os.fork()
    if pid > 0:
    # Exit from first parent
    sys.exit(0)
    except OSError, e:
    sys.stderr.write("Fork #1 failed: %d (%s)\n" % (e.errno, e.strerror))
    sys.exit(1)

    # Decouple from parent environment
    os.chdir("/")
    os.setsid()
    os.umask(0)

    # Second fork
    try:
    pid = os.fork()
    if pid > 0:
    # Exit from second parent
    sys.exit(0)
    except OSError, e:
    sys.stderr.write("Fork #2 failed: %d (%s)\n" % (e.errno, e.strerror))
    sys.exit(1)

    # Redirect standard file descriptors
    sys.stdout.flush()
    sys.stderr.flush()
    si = file(self.stdin, 'r')
    so = file(self.stdout, 'a+')
    se = file(self.stderr, 'a+', 0)
    os.dup2(si.fileno(), sys.stdin.fileno())
    os.dup2(so.fileno(), sys.stdout.fileno())
    os.dup2(se.fileno(), sys.stderr.fileno())

    # Write the PID file
    atexit.register(self.delpid)
    pid = str(os.getpid())
    file(self.pidfile, 'w+').write("%s\n" % pid)

    def delpid(self):
    # Removes the PID file
    os.remove(self.pidfile)

    def start(self):
    '''
    Start the daemon.
    '''
    # Check for a PID file to see if the Daemon is already running
    try:
    pf = file(self.pidfile, 'r')
    pid = int(pf.read().strip())
    pf.close()
    except IOError:
    pid = None

    if pid:
    message = "PID file %s already exist. Daemon already running?\n"
    sys.stderr.write(message % self.pidfile)
    sys.exit(1)

    # No PID file, start the daemon
    self.daemonize()
    self.run()

    def stop(self):
    '''
    Stop the daemon.
    '''
    # Get the PID from the PID file
    try:
    pf = file(self.pidfile, 'r')
    pid = int(pf.read().strip())
    pf.close()
    except IOError:
    pid = None

    if not pid:
    message = "PID file %s does not exist. Daemon not running?\n"
    sys.stderr.write(message % self.pidfile)
    return # not an error in a restart

    # Try to kill the daemon process
    try:
    while 1:
    os.kill(pid, SIGTERM)
    time.sleep(0.1)
    except OSError, err:
    err = str(err)
    if err.find("No such process") > 0:
    if os.path.exists(self.pidfile):
    os.remove(self.pidfile)
    else:
    print str(err)
    sys.exit(1)

    def restart(self):
    '''
    Restart the daemon.
    '''
    self.stop()
    self.start()

    def run(self):
    '''
    The script to execute by the daemon after it starts.
    '''
    pass