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

   1 // Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
   2 package org.rocksdb;
   3
   4 /**
   5  * <p>A TransactionLogIterator is used to iterate over the transactions in a db.
   6  * One run of the iterator is continuous, i.e. the iterator will stop at the
   7  * beginning of any gap in sequences.</p>
   8  */
   9 public class TransactionLogIterator extends RocksObject {
  10
  11   /**
  12    * <p>An iterator is either positioned at a WriteBatch
  13    * or not valid. This method returns true if the iterator
  14    * is valid. Can read data from a valid iterator.</p>
  15    *
  16    * @return true if iterator position is valid.
  17    */
  18   public boolean isValid() {
  19     return isValid(nativeHandle_);
  20   }
  21
  22   /**
  23    * <p>Moves the iterator to the next WriteBatch.
  24    * <strong>REQUIRES</strong>: Valid() to be true.</p>
  25    */
  26   public void next() {
  27     next(nativeHandle_);
  28   }
  29
  30   /**
  31    * <p>Throws RocksDBException if something went wrong.</p>
  32    *
  33    * @throws org.rocksdb.RocksDBException if something went
  34    *     wrong in the underlying C++ code.
  35    */
  36   public void status() throws RocksDBException {
  37     status(nativeHandle_);
  38   }
  39
  40   /**
  41    * <p>If iterator position is valid, return the current
  42    * write_batch and the sequence number of the earliest
  43    * transaction contained in the batch.</p>
  44    *
  45    * <p>ONLY use if Valid() is true and status() is OK.</p>
  46    *
  47    * @return {@link org.rocksdb.TransactionLogIterator.BatchResult}
  48    *     instance.
  49    */
  50   public BatchResult getBatch() {
  51     assert(isValid());
  52     return getBatch(nativeHandle_);
  53   }
  54
  55   /**
  56    * <p>TransactionLogIterator constructor.</p>
  57    *
  58    * @param nativeHandle address to native address.
  59    */
  60   TransactionLogIterator(final long nativeHandle) {
  61     super(nativeHandle);
  62   }
  63
  64   /**
  65    * <p>BatchResult represents a data structure returned
  66    * by a TransactionLogIterator containing a sequence
  67    * number and a {@link WriteBatch} instance.</p>
  68    */
  69   public static final class BatchResult {
  70     /**
  71      * <p>Constructor of BatchResult class.</p>
  72      *
  73      * @param sequenceNumber related to this BatchResult instance.
  74      * @param nativeHandle to {@link org.rocksdb.WriteBatch}
  75      *     native instance.
  76      */
  77     public BatchResult(final long sequenceNumber,
  78         final long nativeHandle) {
  79       sequenceNumber_ = sequenceNumber;
  80       writeBatch_ = new WriteBatch(nativeHandle, true);
  81     }
  82
  83     /**
  84      * <p>Return sequence number related to this BatchResult.</p>
  85      *
  86      * @return Sequence number.
  87      */
  88     public long sequenceNumber() {
  89       return sequenceNumber_;
  90     }
  91
  92     /**
  93      * <p>Return contained {@link org.rocksdb.WriteBatch}
  94      * instance</p>
  95      *
  96      * @return {@link org.rocksdb.WriteBatch} instance.
  97      */
  98     public WriteBatch writeBatch() {
  99       return writeBatch_;
 100     }
 101
 102     private final long sequenceNumber_;
 103     private final WriteBatch writeBatch_;
 104   }
 105
 106   @Override protected final native void disposeInternal(final long handle);
 107   private native boolean isValid(long handle);
 108   private native void next(long handle);
 109   private native void status(long handle)
 110       throws RocksDBException;
 111   private native BatchResult getBatch(long handle);
 112 }