Package org.rocksdb

Interface RocksIteratorInterface

  • All Known Implementing Classes:
    AbstractRocksIterator, RocksIterator, SstFileReaderIterator, WBWIRocksIterator
    public interface RocksIteratorInterface

    Defines the interface for an Iterator which provides access to data one entry at a time. Multiple implementations are provided by this library. In particular, iterators are provided to access the contents of a DB and Write Batch.

    Multiple threads can invoke const methods on an RocksIterator without external synchronization, but if any of the threads may call a non-const method, all threads accessing the same RocksIterator must use external synchronization.

    See Also:
    RocksObject

    • Method Summary

      All Methods Instance Methods Abstract Methods 
      Modifier and Type Method Description
      boolean isValid()
      An iterator is either positioned at an entry, or not valid.
      void next()
      Moves to the next entry in the source.
      void prev()
      Moves to the previous entry in the source.
      void refresh()
      If supported, renew the iterator to represent the latest state.
      void seek​(byte[] target)
      Position at the first entry in the source whose key is at or past target.
      void seek​(java.nio.ByteBuffer target)
      Position at the first entry in the source whose key is that or past target.
      void seekForPrev​(byte[] target)
      Position at the first entry in the source whose key is that or before target.
      void seekForPrev​(java.nio.ByteBuffer target)
      Position at the last key that is less than or equal to the target key.
      void seekToFirst()
      Position at the first entry in the source.
      void seekToLast()
      Position at the last entry in the source.
      void status()
      If an error has occurred, return it.

    • Method Detail

      • isValid

        boolean isValid()

        An iterator is either positioned at an entry, or not valid. This method returns true if the iterator is valid.

        Returns:
        true if iterator is valid.

      • seekToFirst

        void seekToFirst()

        Position at the first entry in the source. The iterator is Valid() after this call if the source is not empty.

      • seekToLast

        void seekToLast()

        Position at the last entry in the source. The iterator is valid after this call if the source is not empty.

      • seek

        void seek​(byte[] target)

        Position at the first entry in the source whose key is at or past target.

        The iterator is valid after this call if the source contains a key that comes at or past target.

        Parameters:
        target - byte array describing a key or a key prefix to seek for.

      • seekForPrev

        void seekForPrev​(byte[] target)

        Position at the first entry in the source whose key is that or before target.

        The iterator is valid after this call if the source contains a key that comes at or before target.

        Parameters:
        target - byte array describing a key or a key prefix to seek for.

      • seek

        void seek​(java.nio.ByteBuffer target)

        Position at the first entry in the source whose key is that or past target.

        The iterator is valid after this call if the source contains a key that comes at or past target.

        Parameters:
        target - byte array describing a key or a key prefix to seek for. Supports direct buffer only.

      • seekForPrev

        void seekForPrev​(java.nio.ByteBuffer target)

        Position at the last key that is less than or equal to the target key.

        The iterator is valid after this call if the source contains a key that comes at or past target.

        Parameters:
        target - byte array describing a key or a key prefix to seek for. Supports direct buffer only.

      • next

        void next()

        Moves to the next entry in the source. After this call, Valid() is true if the iterator was not positioned at the last entry in the source.

        REQUIRES: isValid()

      • prev

        void prev()

        Moves to the previous entry in the source. After this call, Valid() is true if the iterator was not positioned at the first entry in source.

        REQUIRES: isValid()

      • status

        void status()
     throws RocksDBException

        If an error has occurred, return it. Else return an ok status. If non-blocking IO is requested and this operation cannot be satisfied without doing some IO, then this returns Status::Incomplete().

        Throws:
        RocksDBException - thrown if error happens in underlying native library.

      • refresh

        void refresh()
      throws RocksDBException

        If supported, renew the iterator to represent the latest state. The iterator will be invalidated after the call. Not supported if ReadOptions.setSnapshot(Snapshot) was specified when creating the iterator.

        Throws:
        RocksDBException - thrown if the operation is not supported or an error happens in the underlying native library