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SickRage/cherrypy/lib/lockfile.py
echel0n cec4ed573d Upgraded CherryPy libs to 3.3.0
Switched out sqlite3 libs in favour of SQLAlchemy v0.9, will gradually migrate dialects and scheme to be fully SQLAlchemy compliant for using there ORM with sessions instead of direct.

Fixed getEpisode function to stop making unrequired scene number conversions on already converted data thats available now from cache.
2014-06-04 18:28:59 -07:00

148 lines
3.2 KiB
Python

"""
Platform-independent file locking. Inspired by and modeled after zc.lockfile.
"""
import os
try:
import msvcrt
except ImportError:
pass
try:
import fcntl
except ImportError:
pass
class LockError(Exception):
"Could not obtain a lock"
msg = "Unable to lock %r"
def __init__(self, path):
super(LockError, self).__init__(self.msg % path)
class UnlockError(LockError):
"Could not release a lock"
msg = "Unable to unlock %r"
# first, a default, naive locking implementation
class LockFile(object):
"""
A default, naive locking implementation. Always fails if the file
already exists.
"""
def __init__(self, path):
self.path = path
try:
fd = os.open(path, os.O_CREAT | os.O_WRONLY | os.O_EXCL)
except OSError:
raise LockError(self.path)
os.close(fd)
def release(self):
os.remove(self.path)
def remove(self):
pass
class SystemLockFile(object):
"""
An abstract base class for platform-specific locking.
"""
def __init__(self, path):
self.path = path
try:
# Open lockfile for writing without truncation:
self.fp = open(path, 'r+')
except IOError:
# If the file doesn't exist, IOError is raised; Use a+ instead.
# Note that there may be a race here. Multiple processes
# could fail on the r+ open and open the file a+, but only
# one will get the the lock and write a pid.
self.fp = open(path, 'a+')
try:
self._lock_file()
except:
self.fp.seek(1)
self.fp.close()
del self.fp
raise
self.fp.write(" %s\n" % os.getpid())
self.fp.truncate()
self.fp.flush()
def release(self):
if not hasattr(self, 'fp'):
return
self._unlock_file()
self.fp.close()
del self.fp
def remove(self):
"""
Attempt to remove the file
"""
try:
os.remove(self.path)
except:
pass
#@abc.abstract_method
# def _lock_file(self):
# """Attempt to obtain the lock on self.fp. Raise LockError if not
# acquired."""
def _unlock_file(self):
"""Attempt to obtain the lock on self.fp. Raise UnlockError if not
released."""
class WindowsLockFile(SystemLockFile):
def _lock_file(self):
# Lock just the first byte
try:
msvcrt.locking(self.fp.fileno(), msvcrt.LK_NBLCK, 1)
except IOError:
raise LockError(self.fp.name)
def _unlock_file(self):
try:
self.fp.seek(0)
msvcrt.locking(self.fp.fileno(), msvcrt.LK_UNLCK, 1)
except IOError:
raise UnlockError(self.fp.name)
if 'msvcrt' in globals():
LockFile = WindowsLockFile
class UnixLockFile(SystemLockFile):
def _lock_file(self):
flags = fcntl.LOCK_EX | fcntl.LOCK_NB
try:
fcntl.flock(self.fp.fileno(), flags)
except IOError:
raise LockError(self.fp.name)
# no need to implement _unlock_file, it will be unlocked on close()
if 'fcntl' in globals():
LockFile = UnixLockFile