112 lines
3.5 KiB
Python
112 lines
3.5 KiB
Python
"""
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This is based upon the singleton class from
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`tendo <https://github.com/pycontribs/tendo>`_
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which is under the Python Software Foundation License version 2
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"""
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import atexit
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import os
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import sys
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import state
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try:
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import fcntl # @UnresolvedImport
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except ImportError:
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pass
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class singleinstance(object):
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"""
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Implements a single instance application by creating a lock file
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at appdata.
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"""
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def __init__(self, flavor_id="", daemon=False):
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self.initialized = False
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self.counter = 0
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self.daemon = daemon
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self.lockPid = None
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self.lockfile = os.path.normpath(
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os.path.join(state.appdata, 'singleton%s.lock' % flavor_id))
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if state.enableGUI and not self.daemon and not state.curses:
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# Tells the already running (if any) application to get focus.
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import bitmessageqt
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bitmessageqt.init()
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self.lock()
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self.initialized = True
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atexit.register(self.cleanup)
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def lock(self):
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"""Obtain single instance lock"""
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if self.lockPid is None:
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self.lockPid = os.getpid()
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if sys.platform == 'win32':
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try:
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# file already exists, we try to remove
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# (in case previous execution was interrupted)
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if os.path.exists(self.lockfile):
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os.unlink(self.lockfile)
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self.fd = os.open(
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self.lockfile,
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os.O_CREAT | os.O_EXCL | os.O_RDWR | os.O_TRUNC
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)
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except OSError as e:
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if e.errno == 13:
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sys.exit(
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'Another instance of this application is'
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' already running')
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raise
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else:
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pidLine = "%i\n" % self.lockPid
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os.write(self.fd, pidLine)
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else: # non Windows
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self.fp = open(self.lockfile, 'a+')
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try:
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if self.daemon and self.lockPid != os.getpid():
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# wait for parent to finish
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fcntl.lockf(self.fp, fcntl.LOCK_EX)
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else:
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fcntl.lockf(self.fp, fcntl.LOCK_EX | fcntl.LOCK_NB)
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self.lockPid = os.getpid()
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except IOError:
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sys.exit(
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'Another instance of this application is'
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' already running')
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else:
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pidLine = "%i\n" % self.lockPid
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self.fp.truncate(0)
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self.fp.write(pidLine)
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self.fp.flush()
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def cleanup(self):
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"""Release single instance lock"""
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if not self.initialized:
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return
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if self.daemon and self.lockPid == os.getpid():
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# these are the two initial forks while daemonizing
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try:
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if sys.platform == 'win32':
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if hasattr(self, 'fd'):
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os.close(self.fd)
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else:
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fcntl.lockf(self.fp, fcntl.LOCK_UN)
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except (IOError, OSError):
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pass
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return
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try:
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if sys.platform == 'win32':
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if hasattr(self, 'fd'):
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os.close(self.fd)
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os.unlink(self.lockfile)
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else:
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fcntl.lockf(self.fp, fcntl.LOCK_UN)
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if os.path.isfile(self.lockfile):
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os.unlink(self.lockfile)
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except (IOError, OSError):
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pass
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