DocumentService - load - only detach persisted document if not saved

[rsoika]

In general we detach a document in the load() and getDocumentsByQuery() method. This is for performance reasons and the fact, that a ItemCollection can hold byte arrays which will be copied by reference.

Problem:
In cases where these methods are called after a document was saved - save() method - in one single transaction, the detach call will discard the changes made to the document before in the save() method.

Solution:
For that reason we need to mark a managed document entity in the save() method, so that the methods load() and getDocumentsByQuery() can evaluate this flag. Depending on the state, the methods can decide the correct behavior.

• In case a document is not flagged (not saved during same transaction), we can still detach the loaded entity
• In case a document is flagged (saved during save transaction) we may not detach it, but make a deepCopy (clone) of the document instance.

This will avoid the effect, that data written to a document get lost in a long running transaction with save and load calls.