Package com.exonum.binding.core.storage.indices

Class KeySetIndexProxy<E>

java.lang.Object
com.exonum.binding.core.proxy.AbstractNativeProxy
com.exonum.binding.core.storage.indices.KeySetIndexProxy<E>
Type Parameters:
E - the type of elements in this set
All Implemented Interfaces:
StorageIndex, Iterable<E>
public final class KeySetIndexProxy<E>
extends AbstractNativeProxy
implements Iterable<E>
A key set is an index that contains no duplicate elements (keys). This implementation does not permit null elements.

The elements are stored as keys in the underlying database in the lexicographical order. As each operation accepting an element needs to pass the entire element to the underlying database as a key, it's better, in terms of performance, to use this index with small elements. If you need to store large elements and can perform operations by hashes of the elements, consider using a ValueSetIndexProxy.

The "destructive" methods of the set, i.e., the ones that change its contents, are specified to throw UnsupportedOperationException if the set has been created with a read-only database view.

All method arguments are non-null by default.

This class is not thread-safe and and its instances shall not be shared between threads.

When the view goes out of scope, this set is destroyed. Subsequent use of the closed set is prohibited and will result in IllegalStateException.

See Also:
ValueSetIndexProxy, View

  • Method Details

    • newInstance

      public static <E extends com.google.protobuf.MessageLite> KeySetIndexProxy<E> newInstance​(String name, View view, Class<E> keyType)
      Creates a new key set storing protobuf messages.
      Type Parameters:
      E - the type of keys in this set; must be a protobuf message that has a public static #parseFrom(byte[]) method
      Parameters:
      name - a unique alphanumeric non-empty identifier of this set in the underlying storage: [a-zA-Z0-9_]
      view - a database view. Must be valid. If a view is read-only, "destructive" operations are not permitted.
      keyType - the class of a key-protobuf message
      Throws:
      IllegalStateException - if the view is not valid
      IllegalArgumentException - if the name is empty

    • newInstance

      public static <E> KeySetIndexProxy<E> newInstance​(String name, View view, Serializer<E> serializer)
      Creates a new key set proxy.
      Type Parameters:
      E - the type of keys in this set
      Parameters:
      name - a unique alphanumeric non-empty identifier of this set in the underlying storage: [a-zA-Z0-9_]
      view - a database view. Must be valid. If a view is read-only, "destructive" operations are not permitted.
      serializer - a serializer of set keys
      Throws:
      IllegalStateException - if the view is not valid
      IllegalArgumentException - if the name is empty
      See Also:
      StandardSerializers

    • newInGroupUnsafe

      public static <E> KeySetIndexProxy<E> newInGroupUnsafe​(String groupName, byte[] indexId, View view, Serializer<E> serializer)
      Creates a new key set in a collection group with the given name.

      See a caveat on index identifiers.

      Type Parameters:
      E - the type of keys in this set
      Parameters:
      groupName - a name of the collection group
      indexId - an identifier of this collection in the group, see the caveats
      view - a database view
      serializer - a serializer of set keys
      Returns:
      a new key set
      Throws:
      IllegalStateException - if the view is not valid
      IllegalArgumentException - if the name or index id is empty
      See Also:
      StandardSerializers

    • add

      public void add​(E e)
      Adds a new element to the set. The method has no effect if the set already contains such element.
      Parameters:
      e - an element to add
      Throws:
      IllegalStateException - if this set is not valid
      UnsupportedOperationException - if this set is read-only

    • clear

      public void clear()
      Removes all of the elements from this set. The set will be empty after this method returns.
      Throws:
      IllegalStateException - if this set is not valid
      UnsupportedOperationException - if this set is read-only

    • contains

      public boolean contains​(E e)
      Returns true if this set contains the specified element.
      Throws:
      IllegalStateException - if this set is not valid

    • iterator

      public Iterator<E> iterator()
      Creates an iterator over the set elements. The elements are ordered lexicographically.
      Specified by:
      iterator in interface Iterable<E>
      Returns:
      an iterator over the elements of this set
      Throws:
      IllegalStateException - if this set is not valid

    • stream

      public Stream<E> stream()
      Returns a stream of the set elements. The elements are ordered lexicographically.
      Throws:
      IllegalStateException - if this set is not valid

    • remove

      public void remove​(E e)
      Removes the element from this set. If it's not in the set, does nothing.
      Parameters:
      e - an element to remove.
      Throws:
      IllegalStateException - if this set is not valid
      UnsupportedOperationException - if this set is read-only

    • getAddress

      public IndexAddress getAddress()
      Description copied from interface: StorageIndex
      Returns the index address: its unique identifier in the database. It consists of the name and, in case this index belongs to an index family, a family identifier.
      Specified by:
      getAddress in interface StorageIndex

    • toString

      public String toString()
      Overrides:
      toString in class Object