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

   1 // Copyright (c) 2011-present, 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  * <p>An iterator that yields a sequence of key/value pairs from a source.
  10  * Multiple implementations are provided by this library.
  11  * In particular, iterators are provided
  12  * to access the contents of a Table or a DB.</p>
  13  *
  14  * <p>Multiple threads can invoke const methods on an RocksIterator without
  15  * external synchronization, but if any of the threads may call a
  16  * non-const method, all threads accessing the same RocksIterator must use
  17  * external synchronization.</p>
  18  *
  19  * @see org.rocksdb.RocksObject
  20  */
  21 public class RocksIterator extends AbstractRocksIterator<RocksDB> {
  22   protected RocksIterator(RocksDB rocksDB, long nativeHandle) {
  23     super(rocksDB, nativeHandle);
  24   }
  25
  26   /**
  27    * <p>Return the key for the current entry.  The underlying storage for
  28    * the returned slice is valid only until the next modification of
  29    * the iterator.</p>
  30    *
  31    * <p>REQUIRES: {@link #isValid()}</p>
  32    *
  33    * @return key for the current entry.
  34    */
  35   public byte[] key() {
  36     assert(isOwningHandle());
  37     return key0(nativeHandle_);
  38   }
  39
  40   /**
  41    * <p>Return the value for the current entry.  The underlying storage for
  42    * the returned slice is valid only until the next modification of
  43    * the iterator.</p>
  44    *
  45    * <p>REQUIRES: !AtEnd() &amp;&amp; !AtStart()</p>
  46    * @return value for the current entry.
  47    */
  48   public byte[] value() {
  49     assert(isOwningHandle());
  50     return value0(nativeHandle_);
  51   }
  52
  53   @Override protected final native void disposeInternal(final long handle);
  54   @Override final native boolean isValid0(long handle);
  55   @Override final native void seekToFirst0(long handle);
  56   @Override final native void seekToLast0(long handle);
  57   @Override final native void next0(long handle);
  58   @Override final native void prev0(long handle);
  59   @Override final native void seek0(long handle, byte[] target, int targetLen);
  60   @Override final native void status0(long handle) throws RocksDBException;
  61
  62   private native byte[] key0(long handle);
  63   private native byte[] value0(long handle);
  64 }