8254162: Implementation of Foreign-Memory Access API (Third Incubator)

Reviewed-by: erikj, psandoz, alanb

src/java.base/share/classes/java/nio/Buffer.java

@@ -29,6 +29,7 @@ import jdk.internal.access.JavaNioAccess;
 import jdk.internal.access.SharedSecrets;
 import jdk.internal.access.foreign.MemorySegmentProxy;
 import jdk.internal.access.foreign.UnmapperProxy;
+import jdk.internal.misc.ScopedMemoryAccess;
 import jdk.internal.misc.Unsafe;
 import jdk.internal.misc.VM.BufferPool;
 import jdk.internal.vm.annotation.ForceInline;
@@ -193,6 +194,8 @@ public abstract class Buffer {
     // Cached unsafe-access object
     static final Unsafe UNSAFE = Unsafe.getUnsafe();
 
+    static final ScopedMemoryAccess SCOPED_MEMORY_ACCESS = ScopedMemoryAccess.getScopedMemoryAccess();
+
     /**
      * The characteristics of Spliterators that traverse and split elements
      * maintained in Buffers.
@@ -754,9 +757,18 @@ public abstract class Buffer {
     }
 
     @ForceInline
-    final void checkSegment() {
+    final ScopedMemoryAccess.Scope scope() {
         if (segment != null) {
-            segment.checkValidState();
+            return segment.scope();
+        } else {
+            return null;
+        }
+    }
+
+    final void checkScope() {
+        ScopedMemoryAccess.Scope scope = scope();
+        if (scope != null) {
+            scope.checkValidState();
         }
     }
 
@@ -827,6 +839,21 @@ public abstract class Buffer {
                 public boolean isLoaded(long address, boolean isSync, long size) {
                     return MappedMemoryUtils.isLoaded(address, isSync, size);
                 }
+
+                @Override
+                public void reserveMemory(long size, long cap) {
+                    Bits.reserveMemory(size, cap);
+                }
+
+                @Override
+                public void unreserveMemory(long size, long cap) {
+                    Bits.unreserveMemory(size, cap);
+                }
+
+                @Override
+                public int pageSize() {
+                    return Bits.pageSize();
+                }
             });
     }