app/django/core/files/locks.py
author Lennard de Rijk <ljvderijk@gmail.com>
Mon, 16 Feb 2009 20:38:35 +0000
changeset 1364 b2709805fafe
parent 323 ff1a9aa48cfd
permissions -rw-r--r--
Update org bulk accept script. The script now: 1) leaves correctly control to the browser to update the GUI of the progress bar during ajax communication. 2) Displays an error if something went wrong (I've tried in my box stopping the server while doing the requests), and show a retry button to fetch again the list of the applications that are still not accepted and iterate over them again (seems to recover correctly restarting the server after the error in my box) 3) doesn't display any text at the beginning, and the button has the correct CSS class assigned 4) Check if there are applications to accept, if not displays a message stating that there are no orgs to accept. Patch by: Mario Ferraro Reviewed by: Lennard de Rijk

"""
Portable file locking utilities.

Based partially on example by Jonathan Feignberg <jdf@pobox.com> in the Python
Cookbook, licensed under the Python Software License.

    http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/65203

Example Usage::

    >>> from django.core.files import locks
    >>> f = open('./file', 'wb')
    >>> locks.lock(f, locks.LOCK_EX)
    >>> f.write('Django')
    >>> f.close()
"""

__all__ = ('LOCK_EX','LOCK_SH','LOCK_NB','lock','unlock')

system_type = None

try:
    import win32con
    import win32file
    import pywintypes
    LOCK_EX = win32con.LOCKFILE_EXCLUSIVE_LOCK
    LOCK_SH = 0
    LOCK_NB = win32con.LOCKFILE_FAIL_IMMEDIATELY
    __overlapped = pywintypes.OVERLAPPED()
    system_type = 'nt'
except (ImportError, AttributeError):
    pass

try:
    import fcntl
    LOCK_EX = fcntl.LOCK_EX
    LOCK_SH = fcntl.LOCK_SH
    LOCK_NB = fcntl.LOCK_NB
    system_type = 'posix'
except (ImportError, AttributeError):
    pass

def fd(f):
    """Get a filedescriptor from something which could be a file or an fd."""
    return hasattr(f, 'fileno') and f.fileno() or f

if system_type == 'nt':
    def lock(file, flags):
        hfile = win32file._get_osfhandle(fd(file))
        win32file.LockFileEx(hfile, flags, 0, -0x10000, __overlapped)

    def unlock(file):
        hfile = win32file._get_osfhandle(fd(file))
        win32file.UnlockFileEx(hfile, 0, -0x10000, __overlapped)
elif system_type == 'posix':
    def lock(file, flags):
        fcntl.lockf(fd(file), flags)

    def unlock(file):
        fcntl.lockf(fd(file), fcntl.LOCK_UN)
else:
    # File locking is not supported.
    LOCK_EX = LOCK_SH = LOCK_NB = None

    # Dummy functions that don't do anything.
    def lock(file, flags):
        pass

    def unlock(file):
        pass