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

Class ValueSetIndexProxy<E>

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

The elements are stored in the underlying database as values, whereas their cryptographic hashes are used as keys, making this set implementation more suitable for storing large elements. If your application has small elements and does not need to perform set operations by hashes of the elements, consider using a KeySetIndexProxy.

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:
KeySetIndexProxy, View

  • Method Details

    • newInstance

      public static <E extends com.google.protobuf.MessageLite> ValueSetIndexProxy<E> newInstance​(String name, View view, Class<E> valueType)
      Creates a new value set storing protobuf messages.
      Type Parameters:
      E - the type of values 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.
      valueType - the class of values-protobuf messages
      Throws:
      IllegalStateException - if the view is not valid
      IllegalArgumentException - if the name is empty

    • newInstance

      public static <E> ValueSetIndexProxy<E> newInstance​(String name, View view, Serializer<E> serializer)
      Creates a new value set.
      Type Parameters:
      E - the type of values 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 values
      Throws:
      IllegalStateException - if the view is not valid
      IllegalArgumentException - if the name is empty
      See Also:
      StandardSerializers

    • newInGroupUnsafe

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

      See a caveat on index identifiers.

      Type Parameters:
      E - the type of values 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 values
      Returns:
      a new value 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
      See Also:
      containsByHash(HashCode)

    • containsByHash

      public boolean containsByHash​(HashCode elementHash)
      Returns true if this set contains an element with the specified hash.
      Parameters:
      elementHash - a hash of an element
      Throws:
      IllegalStateException - if this set is not valid

    • hashes

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

    • iterator

      public Iterator<ValueSetIndexProxy.Entry<E>> iterator()
      Returns an iterator over the entries of this set. An entry is a hash-value pair. The entries are ordered by hashes lexicographically.
      Specified by:
      iterator in interface Iterable<E>
      Returns:
      an iterator over the entries of this set
      Throws:
      IllegalStateException - if this set is not valid

    • stream

      public Stream<ValueSetIndexProxy.Entry<E>> stream()
      Returns a stream of the entries in this set. An entry is a hash-value pair. The entries are ordered by hashes 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

    • removeByHash

      public void removeByHash​(HashCode elementHash)
      Removes an element from this set by its hash. If there is no such element in the set, does nothing.
      Parameters:
      elementHash - the hash of 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