Greetings developers,
after some hours of debugging a weird phenomena in my application I
have a question about String .intern() usage in the equals() method of
org.apache.slide.common.PropertyName.
Quick summary:
* problem with retrieving properties from a NodeRevisionDescriptor,
when updating org.apache.slide.common.PropertyName to trunk
(SVN r429274)
* problem goes away if reverting change to PropertyName#equals,
changing line 179 from:
return this.name == that.name && this.namespace == that.namespace;
to:
return this.name.equals(that.name) &&
this.namespace.equals(that.namespace);
(ie backing out r429274)
Background information:
I am using org.apache.slide.store.txjndi.JNDIPrincipalStore for
retrieving user and group information from an LDAP server. When updating
Slide from SVN trunk my groups started loosing all it's members [1]
after some initial time - everything works fine at first
NodeRevisionDescriptor property access, but not on subsequent property
reads.
Metacode for my usecase (based on the repository block from Cocoon
v2.1.6):
[code]
public static final PropertyName GROUP_MEMBER_SET =
PropertyName.getPropertyName("group-member-set");
...
SlideToken slideToken =
new SlideTokenImpl(new CredentialsToken(caller));
Structure structure = nat.getStructureHelper();
Content content = nat.getContentHelper();
ObjectNode object = structure.retrieve(slideToken,path);
String uri = object.getUri();
NodeRevisionDescriptors revisions =
content.retrieve(slideToken, uri);
NodeRevisionDescriptor revision =
content.retrieve(slideToken, revisions);
NodeProperty property =
revision.getProperty(GROUP_MEMBER_SET);
[/code]
The last line tries to get the DAV:group-member-set property from the
NodeRevisionDescriptor. This works fine on first access, but after a
subsequent update of the revision descriptor due to JNDIPrincipalStore
executing it's background RefreshThread to refresh the descriptor from
LDAP, the PropertyName for DAV:group-member-set used for access is no
longer considered equal to the PropertyName for DAV:group-member-set
in "properties" hashtable of the NodeRevisionDescriptor (ie null is
returned for the "property" reference above, although memory
inspection shows that the NodeRevisionDescriptor indeed has the
DAV:group-member-set property in it's property table).
If i back out SVN commit r429274 [2] everything works fine. Reading up
a bit on String.intern() does not make me any wiser, since I think it
ought to work with "==" comparision in PropertyName, but I have a go
vs no-go reproducable system showing that "==" and String equals() does
not behave the same.
Anyone else that had similar problems? Thoughts about this? Would it be
OK to back out r429274?
The SVN comment states performance improvements as reason for changing
"String.equals()" to "==", but I suspect that in recent Java runtimes
this difference might be almost neglectable.
Best regards,
Martin
[1] group->member mapping is implemented by <href/>-values of the
"DAV:group-member-set" property in JNDIPrincipalStore
[2] See
http://mail-archives.apache.org/mod_mbox/jakarta-slide-dev/200608.mbox/[EMAIL PROTECTED]
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