RFR: 8224974: Implement JEP 352

[Brian Burkhalter]

Hi Andrew,

With version 6 [1] of the patch applied, tests throw this exception:

Mapped java.lang.InternalError: java.lang.NullPointerException
	at java.base/jdk.internal.misc.ExtendedMapMode.newMapMode(ExtendedMapMode.java:58)
	at java.base/jdk.internal.misc.ExtendedMapMode.<clinit>(ExtendedMapMode.java:40)
	at java.base/sun.nio.ch.FileChannelImpl.map(FileChannelImpl.java:1007)

Looks like a problem in the initialization order of the static final constants: MAP_MODE_CONSTRUCTOR needs to be initialized first so I think the *_SYNC constants need to be after the static initializer [2].

Sorry for suggesting the change that was the proximate cause of this. :-(

Thanks,

Brian

[1] http://cr.openjdk.java.net/~adinn/8224974/webrev.06/
[2] diff

--- a/src/java.base/share/classes/jdk/internal/misc/ExtendedMapMode.java
+++ b/src/java.base/share/classes/jdk/internal/misc/ExtendedMapMode.java
@@ -37,10 +37,6 @@
 
     static final MethodHandle MAP_MODE_CONSTRUCTOR;
 
-    public static final MapMode READ_ONLY_SYNC = newMapMode("READ_ONLY_SYNC");
-
-    public static final MapMode READ_WRITE_SYNC = newMapMode("READ_WRITE_SYNC");
-
     static {
         try {
             var lookup = MethodHandles.privateLookupIn(MapMode.class, MethodHandles.lookup());
@@ -51,6 +47,10 @@
         }
     }
 
+    public static final MapMode READ_ONLY_SYNC = newMapMode("READ_ONLY_SYNC");
+
+    public static final MapMode READ_WRITE_SYNC = newMapMode("READ_WRITE_SYNC");
+
     private static MapMode newMapMode(String name) {
         try {
             return (MapMode) MAP_MODE_CONSTRUCTOR.invoke(name);

 

> On Jun 5, 2019, at 10:47 AM, Brian Burkhalter <brian.burkhalter at oracle.com> wrote:
> 
> Hi Andrew,
> 
> Please ignore the content below: I see the changes are in version 6 which I had not looked through before posting my previous message.
> 
> Thanks,
> 
> Brian
> 
>> On Jun 5, 2019, at 10:25 AM, Brian Burkhalter <brian.burkhalter at oracle.com <mailto:brian.burkhalter at oracle.com>> wrote:
>> 
>> I suppose these changes will be in version 7. If it is likely that comments will be forthcoming from others then it might be worth waiting to incorporate any further changes in version 7.
>