Package org.hyperledger.besu.plugin.services.storage

Interface KeyValueStorage

  • All Superinterfaces:
    java.lang.AutoCloseable, java.io.Closeable
    public interface KeyValueStorage
extends java.io.Closeable
    Responsible for storing values against keys.

    Behaviour expected with regard to key to value mapping is that of a map, one key maps to one value, when a new value is added with an existing key, that key now points at the new value.

    All keys and values must be non-null.

    • Method Summary

      All Methods Instance Methods Abstract Methods 
      Modifier and Type Method Description
      void clear()
      Deletes all keys and values from the storage.
      boolean containsKey​(byte[] key)
      Whether the key-value storage contains the given key.
      java.util.Optional<byte[]> get​(byte[] key)
      Retrieves the value associated with a given key.
      java.util.Set<byte[]> getAllKeysThat​(java.util.function.Predicate<byte[]> returnCondition)
      Performs an evaluation against each key in the store, returning the set of entries that pass.
      long removeAllKeysUnless​(java.util.function.Predicate<byte[]> retainCondition)
      Performs an evaluation against each key in the store, keeping the entries that pass, removing those that fail.
      KeyValueStorageTransaction startTransaction()
      Begins a fresh transaction, for sequencing operations for later atomic execution.

      • Methods inherited from interface java.io.Closeable

        close

    • Method Detail

      • clear

        void clear()
    throws StorageException
        Deletes all keys and values from the storage.
        Throws:
        StorageException - problem encountered when attempting to clear storage.

      • containsKey

        boolean containsKey​(byte[] key)
             throws StorageException
        Whether the key-value storage contains the given key.
        Parameters:
        key - a key that might be contained in the key-value storage.
        Returns:
        true when the given key is present in keyset, false otherwise.
        Throws:
        StorageException - problem encountered when interacting with the key set.

      • get

        java.util.Optional<byte[]> get​(byte[] key)
                        throws StorageException
        Retrieves the value associated with a given key.
        Parameters:
        key - whose associated value is being retrieved.
        Returns:
        an Optional containing the value associated with the specified key, otherwise empty.
        Throws:
        StorageException - problem encountered during the retrieval attempt.

      • removeAllKeysUnless

        long removeAllKeysUnless​(java.util.function.Predicate<byte[]> retainCondition)
                  throws StorageException
        Performs an evaluation against each key in the store, keeping the entries that pass, removing those that fail.
        Parameters:
        retainCondition - predicate to evaluate each key against, unless the result is null, both the key and associated value must be removed.
        Returns:
        the number of keys removed.
        Throws:
        StorageException - problem encountered when removing data.

      • getAllKeysThat

        java.util.Set<byte[]> getAllKeysThat​(java.util.function.Predicate<byte[]> returnCondition)
        Performs an evaluation against each key in the store, returning the set of entries that pass.
        Parameters:
        returnCondition - predicate to evaluate each key against, unless the result is null, the key is added to the returned list of keys.
        Returns:
        the set of keys that pass the condition.

      • startTransaction

        KeyValueStorageTransaction startTransaction()
                                     throws StorageException
        Begins a fresh transaction, for sequencing operations for later atomic execution.
        Returns:
        transaciton to sequence key-value operations.
        Throws:
        StorageException - problem encountered when starting a new transaction.