1 /*
   2  * Copyright (c) 2008, 2009, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package sun.nio.fs;
  27 
  28 import java.lang.ref.Cleaner.Cleanable;
  29 import jdk.internal.misc.Unsafe;
  30 import jdk.internal.ref.CleanerFactory;
  31 
  32 /**
  33  * A light-weight buffer in native memory.
  34  */
  35 
  36 class NativeBuffer {
  37     private static final Unsafe unsafe = Unsafe.getUnsafe();
  38 
  39     private final long address;
  40     private final int size;
  41     private final Cleanable cleanable;
  42 
  43     // optional "owner" to avoid copying
  44     // (only safe for use by thread-local caches)
  45     private Object owner;
  46 
  47     private static class Deallocator implements Runnable {
  48         private final long address;
  49         Deallocator(long address) {
  50             this.address = address;
  51         }
  52         public void run() {
  53             unsafe.freeMemory(address);
  54         }
  55     }
  56 
  57     NativeBuffer(int size) {
  58         this.address = unsafe.allocateMemory(size);
  59         this.size = size;
  60         this.cleanable = CleanerFactory.cleaner().register(this, new Deallocator(address));
  61     }
  62 
  63     void release() {
  64         NativeBuffers.releaseNativeBuffer(this);
  65     }
  66 
  67     long address() {
  68         return address;
  69     }
  70 
  71     int size() {
  72         return size;
  73     }
  74 
  75     void free() {
  76         cleanable.clean();
  77     }
  78 
  79     // not synchronized; only safe for use by thread-local caches
  80     void setOwner(Object owner) {
  81         this.owner = owner;
  82     }
  83 
  84     // not synchronized; only safe for use by thread-local caches
  85     Object owner() {
  86         return owner;
  87     }
  88 }