8283660: Convert com/sun/jndi/ldap/AbstractLdapNamingEnumeration.java finalizer to Cleaner

[bchristi-git]

Please review this change to replace the finalizer in AbstractLdapNamingEnumeration with Cleaner.

(The first PR for this fix started some substantial discussions, leading to, among other things, the 8314480 java.lang.ref memory ordering spec update.)

In standard fashion, pieces of state required for cleanup (LdapCtx homeCtx, LdapResult res, and LdapClient enumClnt) are moved into a Context object. From there, the change is fairly mechanical.

Details of note:

1. Some operations need to change the state values (the update() method is probably the most interesting). Use of reachabilityFence() ensures memory visibility on the Cleaner thread (per the aforementioned spec update).
2. Subclasses need to access homeCtx; I added a homeCtx() method to read homeCtx from the superclass's state.

The test case is based on a copy of com/sun/jndi/ldap/blits/AddTests/AddNewEntry.java. It confirms that the use of Cleaner does not keep an LdapSearchEnumeration object reachable. The other AbstractLdapNamingEnumeration subclasses (LdapNamingEnumeration and LdapBindingEnumeration) can be expected to behave the same.

Thanks.

Edit: (Re)viewers: due to there being a lot of indentation changes, you might consider enabling the "Hide whitespace" option on the "Files changed" tab. To my eye, it gives a better view of the changes.

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Issue

• JDK-8283660: Convert com/sun/jndi/ldap/AbstractLdapNamingEnumeration.java finalizer to Cleaner (Sub-task - P4)

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