[dna-issues] [JBoss JIRA] Updated: (DNA-194) Implement update JCR capability

[Randall Hauch (JIRA)]

     [ https://jira.jboss.org/jira/browse/DNA-194?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Randall Hauch updated DNA-194:
------------------------------

    Attachment: dna-194-session-cache.patch


Uploaded a patch file that captures the refactoring to pull the management of the session's cached and updated state out of the individual Node and Property implementations and into a new "SessionCache" class.

This class does a couple of different things.  First, it centralizes all of the information about the nodes and properties that have been loaded from the repository source, making it easier to track the cached information as well as track/manage the changes made within the session.  Remember that some activities, such as "refresh" or "save" can be performed on one node but could potentially affect many other objects. By centralizing all the cached and transient state, it's much easier to manage all this information.  It also makes it much easier to alter the data structure used to manage the cache (for example to make it thread-safe), should that be required at a later time.

Second, it manages the Node and Property implementation objects (which can be held onto by clients), ensuring that the same Node and Property instances are always returned for the same logical instance.  These instances are managed by ReferenceMaps, allowing the garbage collector to remove entries when clients no longer hold onto the Node and Property objects (with normal references).  The implementation classes of Node and Property (e.g., AbstractJcrNode and its concrete subclasses, and AbstractJcrProperty and its concrete subclasses) no longer directly hold onto the detailed node and property information being cached in SessionCache, but rather hold identifiers and dynamically look up the information when necessary.  This ensures that a particular Node implementation object obtained for a node will always present the most up-to-date information about the node, even if that information is changed by the session or other objects.  

(Note that it would be very easy for each Node and Property implementation to locally cache the reference to the SessionCache's node information and/or property information, saving some repeated lookups using the SessionCache's methods, but since the SessionCache knows about the implementations it could invalidate these local references when needed.  This could be done at a later time when we've proven that the current simple approach needs to be improved.)

> Implement update JCR capability
> -------------------------------
>
>                 Key: DNA-194
>                 URL: https://jira.jboss.org/jira/browse/DNA-194
>             Project: DNA
>          Issue Type: Sub-task
>          Components: JCR
>            Reporter: Johnny Verhaeg
>            Assignee: Randall Hauch
>             Fix For: 0.4
>
>         Attachments: dna-194-session-cache.patch, DNA-194_move_value_cast.patch
>
>


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