def _lock(fileno):
"""Try to lock a file. Return True on success."""
# closing the file unlocks it, so we don't need to unlock here
if platform.system() == 'Windows':
try:
msvcrt.locking(fileno, msvcrt.LK_NBLCK, 10)
return True
except PermissionError:
return False
else:
try:
fcntl.lockf(fileno, fcntl.LOCK_EX | fcntl.LOCK_NB)
return True
# the docs recommend catching both of these
except (BlockingIOError, PermissionError):
return False
python类LK_NBLCK的实例源码
def trylock(self):
msvcrt.locking(self.lockfile.fileno(), msvcrt.LK_NBLCK, 1)
def _trylock(lockfile):
fileno = lockfile.fileno()
msvcrt.locking(fileno, msvcrt.LK_NBLCK, 1)
def lock(self, no_wait=False):
import msvcrt
if no_wait:
op = msvcrt.LK_NBLCK
else:
op = msvcrt.LK_LOCK
self.fd.seek(0)
msvcrt.locking(self.fd, op, 1)
def trylock(self):
if self.lockfile is None or self.lockfile.closed:
self.lockfile = open(self.path, 'a')
try:
if os.name == 'nt':
msvcrt.locking(self.lockfile.fileno(), msvcrt.LK_NBLCK, 1)
else:
fcntl.lockf(self.lockfile, fcntl.LOCK_EX | fcntl.LOCK_NB)
return True
except IOError,e:
if e.errno in (errno.EACCES, errno.EAGAIN):
return False
raise
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 trylock(self):
msvcrt.locking(self.lockfile.fileno(), msvcrt.LK_NBLCK, 1)
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 trylock(self):
msvcrt.locking(self.lockfile.fileno(), msvcrt.LK_NBLCK, 1)
