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

rev 58228 : 8238665: Add JFR event for direct memory statistics

*** 25,38 ****
--- 25,44 ----
  
  package jdk.internal.misc;
  
  import static java.lang.Thread.State.*;
  
+ import java.util.ArrayList;
  import java.util.Collections;
+ import java.util.List;
  import java.util.Map;
  import java.util.Properties;
  
+ import jdk.internal.access.SharedSecrets;
+ 
+ import sun.nio.ch.FileChannelImpl;
+ 
  public class VM {
  
      // the init level when the VM is fully initialized
      private static final int JAVA_LANG_SYSTEM_INITED     = 1;
      private static final int MODULE_SYSTEM_INITED        = 2;
*** 412,417 ****
--- 418,453 ----
       * Those static fields remain as uninitialized if there is no mapped CDS
       * java heap data or there is any error during initialization of the
       * object class in the archived graph.
       */
      public static native void initializeFromArchive(Class<?> c);
+ 
+     /**
+      * Provides access to information on buffer usage.
+      */
+     public interface BufferPool {
+         String getName();
+         long getCount();
+         long getTotalCapacity();
+         long getMemoryUsed();
+     }
+ 
+     private static class BufferPoolsHolder {
+         static final List<BufferPool> BUFFER_POOLS;
+ 
+         static {
+             ArrayList<BufferPool> bufferPools = new ArrayList<>(3);
+             bufferPools.add(SharedSecrets.getJavaNioAccess().getDirectBufferPool());
+             bufferPools.add(FileChannelImpl.getMappedBufferPool());
+             bufferPools.add(FileChannelImpl.getSyncMappedBufferPool());
+ 
+             BUFFER_POOLS = Collections.unmodifiableList(bufferPools);
+         }
+     }
+ 
+     /**
+      * @return the list of buffer pools. 
+      */
+     public static List<BufferPool> getBufferPools() {
+         return BufferPoolsHolder.BUFFER_POOLS;
+     }
  }