src/java.base/share/classes/jdk/internal/misc/Unsafe.java

@@ -24,13 +24,16 @@
  */
 
 package jdk.internal.misc;
 
 import jdk.internal.HotSpotIntrinsicCandidate;
+import jdk.internal.ref.Cleaner;
 import jdk.internal.vm.annotation.ForceInline;
+import sun.nio.ch.DirectBuffer;
 
 import java.lang.reflect.Field;
+import java.nio.ByteBuffer;
 import java.security.ProtectionDomain;
 
 
 /**
  * A collection of methods for performing low-level, unsafe operations.

@@ -3249,10 +3252,29 @@
         } while (!weakCompareAndSwapLongAcquire(o, offset,
                                                current, current ^ mask));
         return current;
     }
 
+    /**
+     * Deallocates the underlying memory, if any, associated with the given
+     * direct byte buffer.
+     *
+     * @param directBuffer a direct byte buffer
+     * @throws NullPointerException if {@code directBuffer} is null
+     * @throws IllegalArgumentException if {@code directBuffer} is non-direct
+     * @since 9
+     */
+    public void deallocate(ByteBuffer directBuffer) {
+        if (!directBuffer.isDirect())
+            throw new IllegalArgumentException("buffer is non-direct");
+
+        Cleaner cleaner = ((DirectBuffer)directBuffer).cleaner();
+        if (cleaner != null) {
+            cleaner.clean();
+        }
+    }
+
 
 
     /**
      * Ensures that loads before the fence will not be reordered with loads and
      * stores after the fence; a "LoadLoad plus LoadStore barrier".