[TYPO3-core] Hard locking in the core

Kasper Skårhøj kasper2007 at typo3.com
Fri Aug 31 22:01:01 CEST 2007

Hi Folks,

I have implemented hard locking of records in TYPO3 since it was  
requested by Typoheads in Austria (redacted user). The deal is that I  
implemented the APIs and they work on the UI. For them, it is a  
feature necessary for a workflow engine they have dreamt up.

I already have a patch ready for the core for the first alpha  
version. I am evaluating that with Boris now. But for now I will just  
post the description of the feature and how it currently works, based  
on this I would like to know if there are any objections on the core  
team to this feature or other comments (additions/changes). I will  
post the patch for review a bit later.

Here goes:

redacted user approached me to have a hard locking feature built into  
TYPO3 which would be necessary API wise for a workflow system they  
were developing. I have now developed the alpha version of this API,  
ready for testing.

Feature description:
There are three modes:
- [default] : The advisory locking we have had for long, managed by  
t3lib_BEfunc:: (no changes to this)
- "single" : Hard locking, for individual records
- "extended" : Hard locking, for groups of records; locks for records  
on the same page locks down other records on the page. Which tables  
are included in this check depends on a TCA [ctrl] configuration  
"extendedLocking" = TRUE. By default "pages" and "tt_content" are.

The modes are configured through $GLOBALS['TYPO3_CONF_VARS']['BE'] 
The two new modes are managed through t3lib_locking - a new class  
included with t3lib_BEfunc by default.
t3lib_locking has three public methods: is_locked(), lock() and unlock()

Explicit locking: A configuration, $GLOBALS['TYPO3_CONF_VARS']['BE'] 
['recordLockingExplicit'] = TRUE, means that records must be locked  
explicitly before editing or operation on them. Default is that  
records gets locked/unlocked implicitly when edited (see alt_doc.php  
below). Explicit mode is evaluated inside t3lib_locking::is_locked();  
function will also return "true" if no lock is found for the login  
user (when "explicit" mode is set).

Across Workspaces: A configuration, $GLOBALS['TYPO3_CONF_VARS']['BE'] 
['recordLockingAcrossWS'] = TRUE, means that locks for versions in  
other workspaces of all implicated records will block access. By  
default only the live records and any versions in the current  
workspace (unless in Live of course) is checked.

In "single" and "extended" modes:
- TCEmain will check if a record is lock by another user before  
allowing any operation to it.
- alt_doc.php will check for other users locks and if found not edit  
the record. Also, if implicit mode is on (default) a lock will be set/ 
updated for a record when loaded into the form. When the form is  
closed the lock is cleared.

- $GLOBALS['TCA'][$table]['ctrl']['extendedLocking'] = TRUE

- expiry of locks by time	(kasper)
- clean-up during log-out	(kasper)
- admin module for managing locks	(podzeit et al)
- more backend feedback	(podzeit et al)
- implicit locking support by other than alt_doc.php	(podzeit et al?)
- optimized "is_locked" function (which currently make lots of  
expensive look-ups for "extended" mode)
- interface missing for setting explicit locks (podzeit et al)

- kasper

NOTICE: NEW EMAIL for 2007: kasper2007 at typo3.com

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