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lockfile.py - Platform-independent advisory file locks.
Requires Python 2.5 unless you apply 2.4.diff
Locking is done on a per-thread basis instead of a per-process basis.
Usage:
>>> lock = LockFile('somefile')
>>> try:
... lock.acquire()
... except AlreadyLocked:
... print 'somefile', 'is locked already.'
... except LockFailed:
... print 'somefile', 'can\'t be locked.'
... else:
... print 'got lock'
got lock
>>> print lock.is_locked()
True
>>> lock.release()
>>> lock = LockFile('somefile')
>>> print lock.is_locked()
False
>>> with lock:
... print lock.is_locked()
True
>>> print lock.is_locked()
False
>>> lock = LockFile('somefile')
>>> # It is okay to lock twice from the same thread...
>>> with lock:
... lock.acquire()
...
>>> # Though no counter is kept, so you can't unlock multiple times...
>>> print lock.is_locked()
False
Exceptions:
Error - base class for other exceptions
LockError - base class for all locking exceptions
AlreadyLocked - Another thread or process already holds the lock
LockFailed - Lock failed for some other reason
UnlockError - base class for all unlocking exceptions
AlreadyUnlocked - File was not locked.
NotMyLock - File was locked but not by the current thread/process
)absolute_importNcurrent_threadget_nameError LockError LockTimeout
AlreadyLocked
LockFailed UnlockError NotLocked NotMyLock LinkFileLock
MkdirFileLockSQLiteFileLockLockBaselockedc @ s e Zd ZdZdS )r zw
Base class for other exceptions.
>>> try:
... raise Error
... except Exception:
... pass
N)__name__
__module__ __qualname____doc__ r r /usr/lib/python3.6/__init__.pyr J s c @ s e Zd ZdZdS )r z
Base class for error arising from attempts to acquire the lock.
>>> try:
... raise LockError
... except Error:
... pass
N)r r r r r r r r r V s c @ s e Zd ZdZdS )r zRaised when lock creation fails within a user-defined period of time.
>>> try:
... raise LockTimeout
... except LockError:
... pass
N)r r r r r r r r r b s c @ s e Zd ZdZdS )r zSome other thread/process is locking the file.
>>> try:
... raise AlreadyLocked
... except LockError:
... pass
N)r r r r r r r r r m s c @ s e Zd ZdZdS )r zLock file creation failed for some other reason.
>>> try:
... raise LockFailed
... except LockError:
... pass
N)r r r r r r r r r x s c @ s e Zd ZdZdS )r
z
Base class for errors arising from attempts to release the lock.
>>> try:
... raise UnlockError
... except Error:
... pass
N)r r r r r r r r r
s c @ s e Zd ZdZdS )r zRaised when an attempt is made to unlock an unlocked file.
>>> try:
... raise NotLocked
... except UnlockError:
... pass
N)r r r r r r r r r s c @ s e Zd ZdZdS )r zRaised when an attempt is made to unlock a file someone else locked.
>>> try:
... raise NotMyLock
... except UnlockError:
... pass
N)r r r r r r r r r s c @ s> e Zd Zdd ZdddZdd Zdd Zd
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ZdS ) _SharedBasec C s
|| _ d S )N)path)selfr r r r __init__ s z_SharedBase.__init__Nc C s t ddS )a
Acquire the lock.
* If timeout is omitted (or None), wait forever trying to lock the
file.
* If timeout > 0, try to acquire the lock for that many seconds. If
the lock period expires and the file is still locked, raise
LockTimeout.
* If timeout <= 0, raise AlreadyLocked immediately if the file is
already locked.
zimplement in subclassN)NotImplemented)r timeoutr r r acquire s z_SharedBase.acquirec C s t ddS )zX
Release the lock.
If the file is not locked, raise NotLocked.
zimplement in subclassN)r )r r r r release s z_SharedBase.releasec C s | j | S )z*
Context manager support.
)r )r r r r __enter__ s z_SharedBase.__enter__c G s | j dS )z*
Context manager support.
N)r )r Z_excr r r __exit__ s z_SharedBase.__exit__c C s d| j j| jf S )Nz<%s: %r>) __class__r r )r r r r __repr__ s z_SharedBase.__repr__)N) r r r r r r r r! r# r r r r r s
r c sB e Zd ZdZd fdd Zdd Zdd Zd
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Z Z S )r z.Base class for platform-specific lock classes.TNc s t t| j| tjj|d | _tj | _ tj
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}t|dt|}d|d@ | _nd| _tjj| j}tjj|d| j | j| j t| jf | _|| _dS )zi
>>> lock = LockBase('somefile')
>>> lock = LockBase('somefile', threaded=False)
z.lockidentz-%xl z %s%s.%s%sN)superr r osr abspathZ lock_filesocketZ gethostnameZhostnamegetpidpid threadingr getattrhashZtnamedirnamejoin unique_namer )r r threadedr tr$ r/ )r" r r r s
zLockBase.__init__c C s t ddS )z9
Tell whether or not the file is locked.
zimplement in subclassN)r )r r r r is_locked s zLockBase.is_lockedc C s t ddS )zA
Return True if this object is locking the file.
zimplement in subclassN)r )r r r r i_am_locking s zLockBase.i_am_lockingc C s t ddS )zN
Remove a lock. Useful if a locking thread failed to unlock.
zimplement in subclassN)r )r r r r
break_lock s zLockBase.break_lockc C s d| j j| j| jf S )Nz<%s: %r -- %r>)r" r r1 r )r r r r r# s zLockBase.__repr__)TN)
r r r r r r4 r5 r6 r#
__classcell__r r )r" r r s !c O sR t jd| tdd t|d ts.|dd }t|dkrH| rHd|d< | ||S )Nz1Import from %s module instead of lockfile package )
stacklevelr Tr2 )warningswarnDeprecationWarning
isinstancestrlen)clsmodargskwdsr r r
_fl_helper s
rE c O s ddl m} t|jdf| |S )zFactory function provided for backwards compatibility.
Do not use in new code. Instead, import LinkLockFile from the
lockfile.linklockfile module.
r: ) linklockfilezlockfile.linklockfile)r% rF rE LinkLockFile)rC rD rF r r r r
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c O s ddl m} t|jdf| |S )zFactory function provided for backwards compatibility.
Do not use in new code. Instead, import MkdirLockFile from the
lockfile.mkdirlockfile module.
r: )
mkdirlockfilezlockfile.mkdirlockfile)r% rH rE
MkdirLockFile)rC rD rH r r r r % s
c O s ddl m} t|jdf| |S )zFactory function provided for backwards compatibility.
Do not use in new code. Instead, import SQLiteLockFile from the
lockfile.mkdirlockfile module.
r: )sqlitelockfilezlockfile.sqlitelockfile)r% rJ rE ZSQLiteLockFile)rC rD rJ r r r r 0 s
c s fdd}|S )a Decorator which enables locks for decorated function.
Arguments:
- path: path for lockfile.
- timeout (optional): Timeout for acquiring lock.
Usage:
@locked('/var/run/myname', timeout=0)
def myname(...):
...
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