Dan Polansky: expand

2016-03-24T07:15:57Z

expand

← Older revision		Revision as of 07:15, 24 March 2016
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	There is an experimental file locking feature, disabled by default. To enable the feature, choose Tools > Preferences > Environment > Files > Experimental File Locking.		There is an experimental file locking feature, disabled by default. To enable the feature, choose Tools > Preferences > Environment > Files > Experimental File Locking. The feature prevents two users from editing a mind map at the same time, thereby overwriting each other's changes. Available since FreeMind [[Release 0.6.5\|0.6.5]].

			==Algorithm==
			* When opening a mind map, FreeMind creates a lock file unless one already exists.
			* After successful creation of the lock file, FreeMind refreshes the lock file every 4 minutes, by writing the user name and the current time into the lock file.<!-- Code: The refresh is in a thread made via LockManager class. The lock refresh is ensured by LockManager.run(), which calls LockManager.writeSemaphoreFile(). -->
			* Upon opening a mind map, if a fresh lock file exists, FreeMind opens a warning pop-up window stating which user edits the mind map and opens the mind map as read-only. A lock file is considered fresh if the time written into it is no older than 5 minutes, which is the 4 minutes stated above + 1 minute as a reserve. A read-only mind map can still be edited but cannot be saved and has to be saved-as if the content is to be preserved. <!-- Code: the check for staleness is in LockManager.tryToLock(), in "if (timeDifference > lockSafetyPeriod)" -->
			* Upon opening a mind map, if a stale lock file exists, FreeMind deletes the stale lock file and opens the mind map for writing. <!-- Code: see the item above -->
			* On Windows, the lock file is attempted to be made a hidden file. <!-- Code: LockManager.tryToLock() and Tools.setHidden() -->
			* Detail: The lock file name is the name of the mind map prefixed with $~ and suffixed with ~. <!-- Code: LockManager.getSemaphoreFile() -->

			==Reliability==
			The feature is experimental. The [[#Bug reports]] section below contains a bug report that (a) provides a bug fix, and (b) reports that, after the bug fix, the reporting user is happy with the feature.

			==Implementation==
			* Class [https://sourceforge.net/p/freemind/code/ci/1.1.0/tree/freemind/freemind/modes/mindmapmode/MindMapMapModel.java MindMapMapModel]
			** Nested class LockManager
			** MindMapMapModel.tryToLock(): calls lockManager.tryToLock().
			** MindMapMapModel.destroy(): calls lockManager.releaseLock() and lockManager.releaseTimer().
			* Class [https://sourceforge.net/p/freemind/code/ci/1.1.0/tree/freemind/freemind/main/Tools.java Tools], Tools.setHidden().

			==Bug reports==
			* [https://sourceforge.net/p/freemind/bugs/976/ fix for experimental file locking on windows], 2010-09-05 - contains a fix for LockManager.writeSemaphoreFile() consisting in catching an exception.

	==See also==		==See also==

Dan Polansky at 17:50, 4 June 2009

2009-06-04T17:50:22Z

← Older revision		Revision as of 17:50, 4 June 2009
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	==See also==		==See also==
	* [[~~Multiple users~~]]		* [[Collaboration]]

	[[Category:Development]]		[[Category:Development]]

Dan Polansky: +

2009-06-04T17:49:51Z

New page

There is an experimental file locking feature, disabled by default. To enable the feature, choose Tools > Preferences > Environment > Files > Experimental File Locking.

==See also==
* [[Multiple users]]

[[Category:Development]]

File locking - Revision history

Dan Polansky: expand

Dan Polansky at 17:50, 4 June 2009

Dan Polansky: +