Your IP : 3.129.211.190

Current Path : /lib64/python2.7/Demo/pdist/
Upload File :
Current File : //lib64/python2.7/Demo/pdist/cvslock.pyc

�
��^c@s�dZddlZddlZddlZddlZdZdZdZdZdZ	ddd	��YZ
d
e
fd��YZddd
��YZd�Z
defd��YZdefd��YZed�Zd�Zedkr�e�ndS(s�CVS locking algorithm.

CVS locking strategy
====================

As reverse engineered from the CVS 1.3 sources (file lock.c):

- Locking is done on a per repository basis (but a process can hold
write locks for multiple directories); all lock files are placed in
the repository and have names beginning with "#cvs.".

- Before even attempting to lock, a file "#cvs.tfl.<pid>" is created
(and removed again), to test that we can write the repository.  [The
algorithm can still be fooled (1) if the repository's mode is changed
while attempting to lock; (2) if this file exists and is writable but
the directory is not.]

- While creating the actual read/write lock files (which may exist for
a long time), a "meta-lock" is held.  The meta-lock is a directory
named "#cvs.lock" in the repository.  The meta-lock is also held while
a write lock is held.

- To set a read lock:

        - acquire the meta-lock
        - create the file "#cvs.rfl.<pid>"
        - release the meta-lock

- To set a write lock:

        - acquire the meta-lock
        - check that there are no files called "#cvs.rfl.*"
                - if there are, release the meta-lock, sleep, try again
        - create the file "#cvs.wfl.<pid>"

- To release a write lock:

        - remove the file "#cvs.wfl.<pid>"
        - rmdir the meta-lock

- To release a read lock:

        - remove the file "#cvs.rfl.<pid>"


Additional notes
----------------

- A process should read-lock at most one repository at a time.

- A process may write-lock as many repositories as it wishes (to avoid
deadlocks, I presume it should always lock them top-down in the
directory hierarchy).

- A process should make sure it removes all its lock files and
directories when it crashes.

- Limitation: one user id should not be committing files into the same
repository at the same time.


Turn this into Python code
--------------------------

rl = ReadLock(repository, waittime)

wl = WriteLock(repository, waittime)

list = MultipleWriteLock([repository1, repository2, ...], waittime)

i����Ni
is#cvs.lcks	#cvs.rfl.s	#cvs.wfl.tErrorcBs#eZd�Zd�Zd�ZRS(cCs
||_dS(N(tmsg(tselfR((s*/usr/lib64/python2.7/Demo/pdist/cvslock.pyt__init__`scCs
t|j�S(N(treprR(R((s*/usr/lib64/python2.7/Demo/pdist/cvslock.pyt__repr__cscCs
t|j�S(N(tstrR(R((s*/usr/lib64/python2.7/Demo/pdist/cvslock.pyt__str__fs(t__name__t
__module__RRR(((s*/usr/lib64/python2.7/Demo/pdist/cvslock.pyR^s		tLockedcBseZRS((RR	(((s*/usr/lib64/python2.7/Demo/pdist/cvslock.pyR
jstLockcBsVeZded�Zd�Zd�Zd�Zd�Zd�Zd�Z	d�Z
RS(	t.cCsx||_||_d|_d|_ttj��}|jt	�|_
|jt|�|_|jt
|�|_dS(N(t
repositorytdelaytNonetlockdirtlockfileRtostgetpidtjointCVSLCKtcvslcktCVSRFLtcvsrfltCVSWFLtcvswfl(RR
Rtpid((s*/usr/lib64/python2.7/Demo/pdist/cvslock.pyRps				cCsdGH|j�dS(Nt__del__(tunlock(R((s*/usr/lib64/python2.7/Demo/pdist/cvslock.pyRzscCs�x�y'|j|_tj|jd�dSWqtjk
r�}d|_|dtkr�ytj|j�}Wntjk
r�qnX|j|�qnt	d|j
|f��qXqWdS(Ni�isfailed to lock %s: %s(RRRtmkdirterrorRtEEXISTtstattsleepRR
(RRtst((s*/usr/lib64/python2.7/Demo/pdist/cvslock.pyt
setlockdir~s 	
cCs|j�|j�dS(N(t
unlockfilet	unlockdir(R((s*/usr/lib64/python2.7/Demo/pdist/cvslock.pyR�s
cCsP|jrLdG|jGHytj|j�Wntjk
r?nXd|_ndS(Ntunlink(RRR'RR(R((s*/usr/lib64/python2.7/Demo/pdist/cvslock.pyR%�s	cCsP|jrLdG|jGHytj|j�Wntjk
r?nXd|_ndS(Ntrmdir(RRR(RR(R((s*/usr/lib64/python2.7/Demo/pdist/cvslock.pyR&�s	cCst||j|j�dS(N(R"R
R(RR#((s*/usr/lib64/python2.7/Demo/pdist/cvslock.pyR"�scCstjj|j|�S(N(RtpathRR
(Rtname((s*/usr/lib64/python2.7/Demo/pdist/cvslock.pyR�s(RR	tDELAYRRR$RR%R&R"R(((s*/usr/lib64/python2.7/Demo/pdist/cvslock.pyRns
								cCs�|dkrt|��n|tj}ytj|�}|d}Wntk
rbd|}nXdtjtj��dd!Gd|G|GHtj|�dS(Nisuid %ds[%s]iisWaiting for %s's lock in(	R
R!tST_UIDtpwdtgetpwuidtKeyErrorttimetctimeR"(R#R
Rtuidtpwenttuser((s*/usr/lib64/python2.7/Demo/pdist/cvslock.pyR"�s


tReadLockcBseZed�ZRS(cCsztj|||�d}z<|j�|j|_t|jd�}|j�d}Wd|sk|j�n|j�XdS(Nitwi(	RRR$RRtopentcloseR%R&(RR
Rtoktfp((s*/usr/lib64/python2.7/Demo/pdist/cvslock.pyR�s



(RR	R+R(((s*/usr/lib64/python2.7/Demo/pdist/cvslock.pyR5�st	WriteLockcBseZed�Zd�ZRS(cCs}tj|||�|j�x1|j�}|s6Pn|j�|j|�q W|j|_t|jd�}|j	�dS(NR6(
RRR$t
readers_existR&R"RRR7R8(RR
RR2R:((s*/usr/lib64/python2.7/Demo/pdist/cvslock.pyR�s

cCswtt�}xdtj|j�D]P}|| tkrytj|j|��}Wntjk
rjqnX|SqWdS(N(	tlenRRtlistdirR
R!RRR(RtnR*R#((s*/usr/lib64/python2.7/Demo/pdist/cvslock.pyR<�s(RR	R+RR<(((s*/usr/lib64/python2.7/Demo/pdist/cvslock.pyR;�s
cCsjxcg}xC|D]:}y|jt|d��Wqtk
rI}~PqXqWPt|j||�qWtS(Ni(tappendR;R
R"Rtlist(trepositoriesRtlockstrtinstance((s*/usr/lib64/python2.7/Demo/pdist/cvslock.pytMultipleWriteLock�s
	cCs�ddl}|jdr)|jd}nd}d}d}zDdGHt|�}dGH|j�dGHt|�}dGH|j�WddgGHd|_dgGH|r�|j�ndgGH|r�|j�nd	gGHd}d
gGHd}dgGHXdS(Ni����iRsattempting write lock ...sgot it.sattempting read lock ...iiiii(tsystargvRR;RR5t
exc_traceback(RGR
trltwl((s*/usr/lib64/python2.7/Demo/pdist/cvslock.pyttest�s8

	

t__main__(((t__doc__RR0R!R-R+R RRRRR
RR"R5R;RFRLR(((s*/usr/lib64/python2.7/Demo/pdist/cvslock.pyt<module>Gs&?		!
?>