RFR: 8223260: NamingManager should cache InitialContextFactory

[Peter Levart]

On 1/30/20 8:59 AM, Peter Levart wrote:
> So if you know that the (implementation class of) 
> InitialContextFactory instance is always resolvable (by class name) 
> from the ClassLoader you are using for the caching key (the TCCL), 
> then this utility might be just right for your purpose.

Thinking of the above, your code may obtain the InitialContextFactory 
via two mechanicms:

a) via ServiceLoader.load(InitialContextFactory.class)
b) via the VersionHelper.loadClass(className)


In case of a, the TCCL is used to load the implementation class by the 
ServiceLoader spec:

      * Creates a new service loader for the given service type, using the
      * current thread's {@linkplain java.lang.Thread#getContextClassLoader
      * context class loader}.

In case TCCL is null, the system class loader is tried and failing that, 
bootstrap class loader.

In case of b, the TCCL is used too, if it is set to a non-null value. 
Else the system class loader is used.


So in both cases you should be safe to use the system class loader 
returned from ClassLoader.getSystemClassLoader() if TCCL is null as a 
key for caching and the InitialContextFactory implementation class will 
be resolvable from such key ClassLoader.

Regards, Peter