RFR: 8177845: Need a mechanism to load Graal

[Peter Levart]

On 04/19/2017 09:42 AM, Peter Levart wrote:
>
>
> On 04/19/2017 09:37 AM, Peter Levart wrote:
>>
>>
>> http://cr.openjdk.java.net/~plevart/jdk9-dev/8177845_VM.getSavedProperties/webrev.01/ 
>>
>
> Also, while we are at it, the following javadocs in the 
> getSavedProperty() do not apply any more:
>
>  138      * It accesses a private copy of the system properties so
>  139      * that user's locking of the system properties object will not
>  140      * cause the library to deadlock.
>
> In JDK 9, Properties class does not use locking any more on the 
> Properties instance for get()/getProperty() methods...
>
> Regards, Peter
>

I also noticed the following comment:

     // TODO: the Property Management needs to be refactored and
     // the appropriate prop keys need to be accessible to the
     // calling classes to avoid duplication of keys.
     private static Map<String, String> savedProps;

...which is not entirely true. Neither keys nor values are duplicated 
(they are just referenced in the new copy of the Properties/Map object). 
What is duplicated is an excessive amount of internal objects, such as 
array slots and Map.Entry objects. If this is a concern, then we could 
use the new immutable Map implementation that is available in JDK 9, so 
the following lines in my webrev:

  181         @SuppressWarnings("unchecked")
  182         Map<String, String> sp = new HashMap<>((Map)props);
  183         // only main thread is running at this time, so savedProps and
  184         // its content will be correctly published to threads 
started later
  185         savedProps = Collections.unmodifiableMap(sp);

Could be changed into:

         @SuppressWarnings("unchecked")
         Map<String, String> sp =
             Map.ofEntries(props.entrySet().toArray(new Map.Entry[0]));
         // only main thread is running at this time, so savedProps
         // will be correctly published to threads started later
         savedProps = sp;

...to save some excessive space (the implementation is a linear-probe 
hashtable which keeps keys and values directly in an array without 
wrapping them with  Map.Entry objects).

Regards, Peter