8349107: Remove RMI finalizers

[bchristi-git]

3 finalizers in RMI code can be removed, as they do not perform meaningful cleanup.

jdk.naming.rmi/share/classes/com/sun/jndi/rmi/registry/RegistryContext

RegistryContext.finalize() just calls close(). The close() method does not perform any cleanup per se, but rather "helps the garbage collector" by setting environment and registry to null.

jdk.naming.rmi/share/classes/com/sun/jndi/rmi/registry/RegistryContext.BindingEnumeration

BindingEnumeration.finalize() simply calls close() on the ctx field, itself a RegistryContext (and close() just "helps the GC.")

src/java.rmi/share/classes/sun/rmi/log/LogInputStream

LogInputStream tracks its length with an int field, length. If length ever becomes == 0, LogInputStream's methods will return without doing anything.

The finalizer calls close(), which just sets length = 0.

By the time a LogInputStream becomes unreachable and is finalized, it's a moot point whether length == 0, as no more methods can be called.
If anything, this finalizer could cause a bug. If a LogInputStream were to became unreachable while a method were still running, the finalizer could set the length to 0 while method code is still running and expecting a length != 0.
It's possible that there is a very long standing bug that close() should be calling in.close(), in which case this evaluation will need to be revisited.