I like your idea. I've just checked in some code that implements it. I added the method setImplicitLocking to the TransactionExt interface. This allows to have it available in TransactionImpl *and* in NarrowTransaction.
By this trick I only had to change OJB but not OJBJ2EE_2.
thanks for this interesting patch!
Thomas
Phil Warrick wrote:
Hi,
I have been using the following patch to control the implicit locking flag at the transaction level (instead of a single global setting). I developed it because I wanted to do ODMG reading without implicit locking and to do ODMG writing with implicit locking. Even with a schema that is fully proxied, I found that read locking propagates across the proxies leading to a potentially large graph traversal.
The changes are really just the addition of a setImplicitLocking(boolean) method to the following three classes:
1)org.apache.ojb.odmg.TransactionImpl 2)org.apache.ojb.odmg.OJB 3)org.apache.ojb.odmg.OJBJ2EE_2
This has been tested in both a single JVM setting and in a J2EE/EJB environment.
The changes (below) are so trivial that I didn't do make a true patch file. I hope one of the developers can review these changes and incorporate them if appropriate.
This change can be thought of as an extension to the ODMG api, giving greater control to the locking stategy (the ODMG standard enforces no
particular implicit locking strategy). The global setting "ImplicitLocking" specified in OJB.properties is used when a org.apache.ojb.odmg.TransactionImpl is created. A subsequent call to OJB#setImplicitLocking(boolean) or
OJBJ2EE_2#setImplicitLocking(boolean) within the transaction overrides the global setting.
The reason that I did not use the approach ((OjbConfiguration)getConfiguration()).setUseImplicitLocking(in);
to set the global configuration setting is that this is not thread-safe, as far as I can tell.
Of course if there's an easier way to do this I'd like to know.
Phil
1) org.apache.ojb.odmg.TransactionImpl.java public void setImplicitLocking(boolean in) { useImplicitLocking = in; }
2) org.apache.ojb.odmg.OJB.java public void setImplicitLocking(boolean in) { ((TransactionImpl)currentTransaction()).setImplicitLocking(in); }
3) org.apache.ojb.odmg.OJBJ2EE_2.java public void setImplicitLocking(boolean in) { currentTransaction(); ((TransactionImpl)super.currentTransaction()).setImplicitLocking(in); }
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