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, java.lang.Iterable<ValueSetIndexProxy.Entry<E>>

public final class ValueSetIndexProxy<E>
extends AbstractNativeProxy
implements java.lang.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 access.

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

See Also:
KeySetIndexProxy, Access
  • Method Details

    • newInstance

      public static <E> ValueSetIndexProxy<E> newInstance​(IndexAddress address, AbstractAccess access, Serializer<E> serializer)
      Creates a new value set.

      Warning: do not invoke this method from service code, use Access.getValueSet(IndexAddress, Serializer).

      Type Parameters:
      E - the type of values in this set
      Parameters:
      address - an index address
      access - a database access. Must be valid. If an access is read-only, "destructive" operations are not permitted.
      serializer - a serializer of values
      Throws:
      java.lang.IllegalStateException - if the access is not valid
      java.lang.IllegalArgumentException - if the name 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:
      java.lang.IllegalStateException - if this set is not valid
      java.lang.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:
      java.lang.IllegalStateException - if this set is not valid
      java.lang.UnsupportedOperationException - if this set is read-only
    • contains

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

      public java.util.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:
      java.lang.IllegalStateException - if this set is not valid
    • iterator

      public java.util.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 java.lang.Iterable<E>
      Returns:
      an iterator over the entries of this set
      Throws:
      java.lang.IllegalStateException - if this set is not valid
    • stream

      public java.util.stream.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:
      java.lang.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:
      java.lang.IllegalStateException - if this set is not valid
      java.lang.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:
      java.lang.IllegalStateException - if this set is not valid
      java.lang.UnsupportedOperationException - if this set is read-only
    • getAddress

      public IndexAddress getAddress()
      Description copied from interface: StorageIndex
      Returns the index address: its identifier in the database.

      Please note that the implementations may return either relative or absolute address. The address is not required to be equal to the one passed to the index constructor.

      Specified by:
      getAddress in interface StorageIndex
    • toString

      public java.lang.String toString()
      Overrides:
      toString in class java.lang.Object