Reference client for Bitmessage: a P2P encrypted decentralised communication protocol:
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#! /usr/bin/env python
import sys
import os
import errno
import tempfile
from multiprocessing import Process
class singleinstance:
"""
Implements a single instance application by creating a lock file based on the full path to the script file.
This is based upon the singleton class from tendo https://github.com/pycontribs/tendo
which is under the Python Software Foundation License version 2
"""
def __init__(self, flavor_id=""):
import sys
self.initialized = False
basename = os.path.splitext(os.path.abspath(sys.argv[0]))[0].replace("/", "-").replace(":", "").replace("\\", "-") + '-%s' % flavor_id + '.lock'
self.lockfile = os.path.normpath(tempfile.gettempdir() + '/' + basename)
if sys.platform == 'win32':
try:
# file already exists, we try to remove (in case previous execution was interrupted)
if os.path.exists(self.lockfile):
os.unlink(self.lockfile)
self.fd = os.open(self.lockfile, os.O_CREAT | os.O_EXCL | os.O_RDWR)
except OSError:
type, e, tb = sys.exc_info()
if e.errno == 13:
print 'Another instance of this application is already running'
sys.exit(-1)
print(e.errno)
raise
else: # non Windows
import fcntl # @UnresolvedImport
self.fp = open(self.lockfile, 'w')
try:
fcntl.lockf(self.fp, fcntl.LOCK_EX | fcntl.LOCK_NB)
except IOError:
print 'Another instance of this application is already running'
sys.exit(-1)
self.initialized = True
def __del__(self):
import sys
if not self.initialized:
return
try:
if sys.platform == 'win32':
if hasattr(self, 'fd'):
os.close(self.fd)
os.unlink(self.lockfile)
else:
import fcntl # @UnresolvedImport
fcntl.lockf(self.fp, fcntl.LOCK_UN)
if os.path.isfile(self.lockfile):
os.unlink(self.lockfile)
except Exception, e:
sys.exit(-1)