ceph/src/rocksdb/java/src/main/java/org/rocksdb/RocksMutableObject.java

   1 // Copyright (c) 2016, Facebook, Inc.  All rights reserved.
   2 // This source code is licensed under the BSD-style license found in the
   3 // LICENSE file in the root directory of this source tree. An additional grant
   4 // of patent rights can be found in the PATENTS file in the same directory.
   5
   6 package org.rocksdb;
   7
   8 /**
   9  * RocksMutableObject is an implementation of {@link AbstractNativeReference}
  10  * whose reference to the underlying native C++ object can change.
  11  *
  12  * <p>The use of {@code RocksMutableObject} should be kept to a minimum, as it
  13  * has synchronization overheads and introduces complexity. Instead it is
  14  * recommended to use {@link RocksObject} where possible.</p>
  15  */
  16 public abstract class RocksMutableObject extends AbstractNativeReference {
  17
  18   /**
  19    * An mutable reference to the value of the C++ pointer pointing to some
  20    * underlying native RocksDB C++ object.
  21    */
  22   private long nativeHandle_;
  23   private boolean owningHandle_;
  24
  25   protected RocksMutableObject() {
  26   }
  27
  28   protected RocksMutableObject(final long nativeHandle) {
  29     this.nativeHandle_ = nativeHandle;
  30     this.owningHandle_ = true;
  31   }
  32
  33   /**
  34    * Closes the existing handle, and changes the handle to the new handle
  35    *
  36    * @param newNativeHandle The C++ pointer to the new native object
  37    * @param owningNativeHandle true if we own the new native object
  38    */
  39   public synchronized void resetNativeHandle(final long newNativeHandle,
  40       final boolean owningNativeHandle) {
  41     close();
  42     setNativeHandle(newNativeHandle, owningNativeHandle);
  43   }
  44
  45   /**
  46    * Sets the handle (C++ pointer) of the underlying C++ native object
  47    *
  48    * @param nativeHandle The C++ pointer to the native object
  49    * @param owningNativeHandle true if we own the native object
  50    */
  51   public synchronized void setNativeHandle(final long nativeHandle,
  52       final boolean owningNativeHandle) {
  53     this.nativeHandle_ = nativeHandle;
  54     this.owningHandle_ = owningNativeHandle;
  55   }
  56
  57   @Override
  58   protected synchronized boolean isOwningHandle() {
  59     return this.owningHandle_;
  60   }
  61
  62   /**
  63    * Gets the value of the C++ pointer pointing to the underlying
  64    * native C++ object
  65    *
  66    * @return the pointer value for the native object
  67    */
  68   protected synchronized long getNativeHandle() {
  69     assert (this.nativeHandle_ != 0);
  70     return this.nativeHandle_;
  71   }
  72
  73   @Override
  74   public synchronized final void close() {
  75     if (isOwningHandle()) {
  76       disposeInternal();
  77       this.owningHandle_ = false;
  78       this.nativeHandle_ = 0;
  79     }
  80   }
  81
  82   protected void disposeInternal() {
  83     disposeInternal(nativeHandle_);
  84   }
  85
  86   protected abstract void disposeInternal(final long handle);
  87 }