Lockfiles for inter-process communication
These are used for synchronization between processes, unlike
thread.LockType locks. The common use is non-blocking lock attempts.
For convenience and in order to reduce confusion with the (somewhat odd)
thread lock interface, these locks have a different interface.
attempt() try to obtain the lock, return boolean success
obtain() wait to obtain the lock, returns None
release() release an obtained lock, returns None
locked() returns True if any thread IN THIS PROCESS
has obtained the lock, else False
In general, you should assume that only the LockFile class will be
available. Only use a more-specific lockfile type if you have need
of compatibility with non-PEAK software that uses that special type
of lockfile. (In practice, this means that the only time you'll ever
use anything other than the generic LockFile class is if you need
to work with something on a Unix-like platform that uses the equivalent
of FLockFile, as SHLockFile is the default implementation of LockFile
on Unix-like platforms.)
Currently, only Unix-ish and Windows platforms supported; if your platform
isn't supported, not even the LockFile class will be available from this
module. For Windows, the msvcrt module must be available (it is in the
standard Python 2.2.1 binary distribution for Windows).
This module also exports a NullLockFile class, for use when locking is
not needed, but an object with a locking interface is nonetheless required.
NullLockFile can also be used as a substitute for a thread lock, if you
prefer this locking interface over the standard Python one.
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Imported modules
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import errno
from interfaces import ILock
import os
from peak.api import naming, protocols
from peak.naming.factories.openable import FileURL
from peak.util.threads import allocate_lock
import time
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Functions
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check_lock
make_tempfile
pid_exists
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check_lock
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check_lock ( fn )
Check the validity of an existing lock file
Reads the PID out of the lock and check if that process exists
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make_tempfile
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make_tempfile ( fn, pid )
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pid_exists
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pid_exists ( pid )
Is there a process with PID pid?
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Classes
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