daemon: prevent races by opening with O_EXCL
Rework the way the daemon and server are created. If we might want to create a daemon, try to grab the lockfile with O_EXCL. If we got it, create a server and daemon, otherwise try and connect to the server. If connecting to the server fails (including after sleeping a little in case the server was recently created), remove the lockfile and start over. Other fix: shut down network gracefully on daemon exit. Fixes #1638
This commit is contained in:
Neil Booth
parent
69da96feb4
commit
e6020975a5
157
lib/daemon.py
157
lib/daemon.py
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@ -19,6 +19,7 @@
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import ast
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import os
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import sys
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import time
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import jsonrpclib
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from jsonrpclib.SimpleJSONRPCServer import SimpleJSONRPCServer, SimpleJSONRPCRequestHandler
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@ -49,7 +50,6 @@ def get_daemon(config):
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except:
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pass
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class RequestHandler(SimpleJSONRPCRequestHandler):
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def do_OPTIONS(self):
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@ -66,7 +66,7 @@ class RequestHandler(SimpleJSONRPCRequestHandler):
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class Daemon(DaemonThread):
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def __init__(self, config):
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def __init__(self, config, server):
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DaemonThread.__init__(self)
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self.config = config
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if config.get('offline'):
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@ -78,18 +78,15 @@ class Daemon(DaemonThread):
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self.wallets = {}
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self.wallet = None
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self.cmd_runner = Commands(self.config, self.wallet, self.network)
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host = config.get('rpchost', 'localhost')
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port = config.get('rpcport', 0)
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self.server = SimpleJSONRPCServer((host, port), requestHandler=RequestHandler, logRequests=False)
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with open(lockfile(config), 'w') as f:
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f.write(repr(self.server.socket.getsockname()))
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self.server.timeout = 0.1
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self.server = server
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# Setup server
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server.timeout = 0.1
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for cmdname in known_commands:
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self.server.register_function(getattr(self.cmd_runner, cmdname), cmdname)
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self.server.register_function(self.run_cmdline, 'run_cmdline')
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self.server.register_function(self.ping, 'ping')
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self.server.register_function(self.run_daemon, 'daemon')
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self.server.register_function(self.run_gui, 'gui')
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server.register_function(getattr(self.cmd_runner, cmdname), cmdname)
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server.register_function(self.run_cmdline, 'run_cmdline')
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server.register_function(self.ping, 'ping')
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server.register_function(self.run_daemon, 'daemon')
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server.register_function(self.run_gui, 'gui')
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def ping(self):
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return True
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@ -178,11 +175,16 @@ class Daemon(DaemonThread):
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def run(self):
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while self.is_running():
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self.server.handle_request()
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os.unlink(lockfile(self.config))
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def stop(self):
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for k, wallet in self.wallets.items():
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wallet.stop_threads()
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if self.network:
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self.print_error("shutting down network")
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self.network.stop()
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self.network.join()
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def stop(self):
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self.print_error("stopping, removing lockfile")
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Daemon.remove_lockfile(Daemon.lockfile(self.config))
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DaemonThread.stop(self)
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def init_gui(self, config, plugins):
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@ -194,19 +196,78 @@ class Daemon(DaemonThread):
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self.gui.main()
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@staticmethod
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def gui_command(config, config_options, plugins):
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server = get_daemon(config)
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if server is not None:
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return server.gui(config_options)
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def lockfile(config):
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return os.path.join(config.path, 'daemon')
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daemon = Daemon(config)
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@staticmethod
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def remove_lockfile(lockfile):
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os.unlink(lockfile)
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@staticmethod
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def get_fd_or_server(lockfile):
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'''If create is True, tries to create the lockfile, using O_EXCL to
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prevent races. If it succeeds it returns the FD.
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Otherwise try and connect to the server specified in the lockfile.
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If this succeeds, the server is returned. Otherwise remove the
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lockfile and try again.'''
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while True:
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try:
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return os.open(lockfile, os.O_CREAT | os.O_EXCL | os.O_WRONLY)
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except OSError:
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pass
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server = Daemon.get_server(lockfile)
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if server is not None:
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return server
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# Couldn't connect; remove lockfile and try again.
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Daemon.remove_lockfile(lockfile)
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@staticmethod
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def get_server(lockfile):
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while True:
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create_time = None
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try:
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with open(lockfile) as f:
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(host, port), create_time = ast.literal_eval(f.read())
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server = jsonrpclib.Server('http://%s:%d' % (host, port))
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# Test daemon is running
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server.ping()
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return server
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except:
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pass
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if not create_time or create_time < time.time() - 1.0:
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return None
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# Sleep a bit and try again; it might have just been started
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time.sleep(1.0)
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@staticmethod
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def create_daemon(config, fd):
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'''Create a daemon and server when they don't exist.'''
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host = config.get('rpchost', 'localhost')
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port = config.get('rpcport', 0)
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server = SimpleJSONRPCServer((host, port), logRequests=False,
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requestHandler=RequestHandler)
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os.write(fd, repr((server.socket.getsockname(), time.time())))
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os.close(fd)
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daemon = Daemon(config, server)
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daemon.start()
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daemon.init_gui(config, plugins)
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sys.exit(0)
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return daemon
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@staticmethod
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def gui_command(config, config_options, plugins):
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lockfile = Daemon.lockfile(config)
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fd = Daemon.get_fd_or_server(lockfile)
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if isinstance(fd, int):
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daemon = Daemon.create_daemon(config, fd)
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daemon.init_gui(config, plugins)
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sys.exit(0)
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server = fd
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return server.gui(config_options)
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@staticmethod
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def cmdline_command(config, config_options):
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server = get_daemon(config)
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server = get_server(Daemon.lockfile(config))
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if server is not None:
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return False, server.run_cmdline(config_options)
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@ -214,29 +275,31 @@ class Daemon(DaemonThread):
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@staticmethod
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def daemon_command(config, config_options):
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server = get_daemon(config)
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if server is not None:
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return server.daemon(config_options)
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subcommand = config.get('subcommand')
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if subcommand in ['status', 'stop']:
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print_msg("Daemon not running")
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sys.exit(1)
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elif subcommand == 'start':
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lockfile = Daemon.lockfile(config)
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fd = Daemon.get_fd_or_server(lockfile)
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if isinstance(fd, int):
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subcommand = config.get('subcommand')
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if subcommand != 'start':
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if subcommand in ['status', 'stop']:
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print_msg("Daemon not running")
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else:
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print_msg("syntax: electrum daemon <start|status|stop>")
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os.close(fd)
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Daemon.remove_lockfile(lockfile)
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sys.exit(1)
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pid = os.fork()
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if pid == 0:
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daemon = Daemon(config)
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if config.get('websocket_server'):
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from electrum import websockets
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websockets.WebSocketServer(config, daemon.network).start()
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if config.get('requests_dir'):
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check_www_dir(config.get('requests_dir'))
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daemon.start()
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daemon.join()
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sys.exit(0)
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else:
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if pid:
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print_stderr("starting daemon (PID %d)" % pid)
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sys.exit(0)
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else:
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print_msg("syntax: electrum daemon <start|status|stop>")
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sys.exit(1)
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daemon = Daemon.create_daemon(config, fd)
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if config.get('websocket_server'):
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from electrum import websockets
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websockets.WebSocketServer(config, daemon.network).start()
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if config.get('requests_dir'):
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check_www_dir(config.get('requests_dir'))
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daemon.join()
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sys.exit(0)
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server = fd
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if server is not None:
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return server.daemon(config_options)
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