Class LruDictionary<TKey, TValue>

LruDictionary<TKey, TValue> is similar to of Java's HashMap, which has a bounded Limit; When it reaches that Limit, each time a new element is added, the least recently used (LRU) entry is removed.

Unlike the Java Lucene implementation, this one is thread safe because it is backed by the J2N.Collections.Concurrent.LurchTable<TKey, TValue>. Do note that every time an element is read from LruDictionary<TKey, TValue>, a write operation also takes place to update the element's last access time. This is because the LRU order needs to be remembered to determine which element to evict when the Limit is exceeded.

Note

This API is experimental and might change in incompatible ways in the next release.

Inheritance

object

LruDictionary<TKey, TValue>

Implements

IDictionary<TKey, TValue>

ICollection<KeyValuePair<TKey, TValue>>

IEnumerable<KeyValuePair<TKey, TValue>>

IEnumerable

Inherited Members

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object, object)

object.ToString()

Namespace: Lucene.Net.Facet.Taxonomy

Assembly: Lucene.Net.Facet.dll

Syntax

public class LruDictionary<TKey, TValue> : IDictionary<TKey, TValue>, ICollection<KeyValuePair<TKey, TValue>>, IEnumerable<KeyValuePair<TKey, TValue>>, IEnumerable

Type Parameters

Name	Description
TKey
TValue

Constructors

LruDictionary(int)

Create a new hash map with a bounded size and with least recently used entries removed.

Declaration

public LruDictionary(int limit)

Parameters

Type	Name	Description
int	limit	The maximum size (in number of entries) to which the map can grow before the least recently used entries start being removed. Setting limit to a very large value, like MaxValue is allowed, but is less efficient than using J2N.Collections.Generic.Dictionary<TKey, TValue> or Dictionary<TKey, TValue> because our class needs to keep track of the use order (via an additional doubly-linked list) which is not used when the map's size is always below the maximum size.

LruDictionary(int, IEqualityComparer<TKey>)

Create a new hash map with a bounded size and with least recently used entries removed.

LUCENENET specific overload to allow passing in custom IEqualityComparer<T>. See LUCENENET-602.

Declaration

public LruDictionary(int limit, IEqualityComparer<TKey> comparer)

Parameters

Type	Name	Description
int	limit	The maximum size (in number of entries) to which the map can grow before the least recently used entries start being removed. Setting limit to a very large value, like MaxValue is allowed, but is less efficient than using J2N.Collections.Generic.Dictionary<TKey, TValue> or Dictionary<TKey, TValue> because our class needs to keep track of the use order (via an additional doubly-linked list) which is not used when the map's size is always below the maximum size.
IEqualityComparer<TKey>	comparer	The IEqualityComparer<T> implementation to use when comparing keys, or null to use the default IEqualityComparer<T> for the type of the key.

Properties

Count

Gets the number of elements contained in the ICollection<T>.

Declaration

public virtual int Count { get; }

Property Value

Type	Description
int	The number of elements contained in the ICollection<T>.

IsReadOnly

Gets a value indicating whether the ICollection<T> is read-only.

Declaration

public virtual bool IsReadOnly { get; }

Property Value

Type	Description
bool	true if the ICollection<T> is read-only; otherwise, false.

this[TKey]

Gets or sets the element with the specified key.

Declaration

public virtual TValue this[TKey key] { get; set; }

Parameters

Type	Name	Description
TKey	key	The key of the element to get or set.

Property Value

Type	Description
TValue	The element with the specified key.

Exceptions

Type	Condition
ArgumentNullException	key is null.
KeyNotFoundException	The property is retrieved and key is not found.
NotSupportedException	The property is set and the IDictionary<TKey, TValue> is read-only.

Keys

Gets an ICollection<T> containing the keys of the IDictionary<TKey, TValue>.

Declaration

public virtual ICollection<TKey> Keys { get; }

Property Value

Type	Description
ICollection<TKey>	An ICollection<T> containing the keys of the object that implements IDictionary<TKey, TValue>.

Limit

Allows changing the dictionary's maximal number of elements which was defined at construction time.

Note that if the dictionary is already larger than Limit, the current implementation does not shrink it (by removing the oldest elements); Rather, the map remains in its current size as new elements are added, and will only start shrinking (until settling again on the given Limit) if existing elements are explicitly deleted.

Declaration

public virtual int Limit { get; set; }

Property Value

Type	Description
int

Values

Gets an ICollection<T> containing the values in the IDictionary<TKey, TValue>.

Declaration

public virtual ICollection<TValue> Values { get; }

Property Value

Type	Description
ICollection<TValue>	An ICollection<T> containing the values in the object that implements IDictionary<TKey, TValue>.

Methods

Add(KeyValuePair<TKey, TValue>)

Adds an item to the ICollection<T>.

Declaration

public virtual void Add(KeyValuePair<TKey, TValue> item)

Parameters

Type	Name	Description
KeyValuePair<TKey, TValue>	item	The object to add to the ICollection<T>.

Exceptions

Type	Condition
NotSupportedException	The ICollection<T> is read-only.

Add(TKey, TValue)

Adds an element with the provided key and value to the IDictionary<TKey, TValue>.

Declaration

public virtual void Add(TKey key, TValue value)

Parameters

Type	Name	Description
TKey	key	The object to use as the key of the element to add.
TValue	value	The object to use as the value of the element to add.

Exceptions

Type	Condition
ArgumentNullException	key is null.
ArgumentException	An element with the same key already exists in the IDictionary<TKey, TValue>.
NotSupportedException	The IDictionary<TKey, TValue> is read-only.

Clear()

Removes all items from the ICollection<T>.

Declaration

public virtual void Clear()

Exceptions

Type	Condition
NotSupportedException	The ICollection<T> is read-only.

Contains(KeyValuePair<TKey, TValue>)

Determines whether the ICollection<T> contains a specific value.

Declaration

public virtual bool Contains(KeyValuePair<TKey, TValue> item)

Parameters

Type	Name	Description
KeyValuePair<TKey, TValue>	item	The object to locate in the ICollection<T>.

Returns

Type	Description
bool	true if item is found in the ICollection<T>; otherwise, false.

ContainsKey(TKey)

Determines whether the IDictionary<TKey, TValue> contains an element with the specified key.

Declaration

public virtual bool ContainsKey(TKey key)

Parameters

Type	Name	Description
TKey	key	The key to locate in the IDictionary<TKey, TValue>.

Returns

Type	Description
bool	true if the IDictionary<TKey, TValue> contains an element with the key; otherwise, false.

Exceptions

Type	Condition
ArgumentNullException	key is null.

CopyTo(KeyValuePair<TKey, TValue>[], int)

Copies the elements of the ICollection<T> to an Array, starting at a particular Array index.

Declaration

public virtual void CopyTo(KeyValuePair<TKey, TValue>[] array, int index)

Parameters

Type	Name	Description
KeyValuePair<TKey, TValue>[]	array	The one-dimensional Array that is the destination of the elements copied from ICollection<T>. The Array must have zero-based indexing.
int	index

Exceptions

Type	Condition
ArgumentNullException	array is null.
ArgumentOutOfRangeException	arrayIndex is less than 0.
ArgumentException	The number of elements in the source ICollection<T> is greater than the available space from arrayIndex to the end of the destination array.

Get(TKey)

LruDictionary<TKey, TValue> is similar to of Java's HashMap, which has a bounded Limit; When it reaches that Limit, each time a new element is added, the least recently used (LRU) entry is removed.

Unlike the Java Lucene implementation, this one is thread safe because it is backed by the J2N.Collections.Concurrent.LurchTable<TKey, TValue>. Do note that every time an element is read from LruDictionary<TKey, TValue>, a write operation also takes place to update the element's last access time. This is because the LRU order needs to be remembered to determine which element to evict when the Limit is exceeded.

Note

This API is experimental and might change in incompatible ways in the next release.

Declaration

public virtual TValue Get(TKey key)

Parameters

Type	Name	Description
TKey	key

Returns

Type	Description
TValue

GetEnumerator()

Returns an enumerator that iterates through the collection.

Declaration

public virtual IEnumerator<KeyValuePair<TKey, TValue>> GetEnumerator()

Returns

Type	Description
IEnumerator<KeyValuePair<TKey, TValue>>	An enumerator that can be used to iterate through the collection.

Put(TKey, TValue)

LruDictionary<TKey, TValue> is similar to of Java's HashMap, which has a bounded Limit; When it reaches that Limit, each time a new element is added, the least recently used (LRU) entry is removed.

Unlike the Java Lucene implementation, this one is thread safe because it is backed by the J2N.Collections.Concurrent.LurchTable<TKey, TValue>. Do note that every time an element is read from LruDictionary<TKey, TValue>, a write operation also takes place to update the element's last access time. This is because the LRU order needs to be remembered to determine which element to evict when the Limit is exceeded.

Note

This API is experimental and might change in incompatible ways in the next release.

Declaration

public virtual TValue Put(TKey key, TValue value)

Parameters

Type	Name	Description
TKey	key
TValue	value

Returns

Type	Description
TValue

Remove(KeyValuePair<TKey, TValue>)

Removes the first occurrence of a specific object from the ICollection<T>.

Declaration

public virtual bool Remove(KeyValuePair<TKey, TValue> item)

Parameters

Type	Name	Description
KeyValuePair<TKey, TValue>	item	The object to remove from the ICollection<T>.

Returns

Type	Description
bool	true if item was successfully removed from the ICollection<T>; otherwise, false. This method also returns false if item is not found in the original ICollection<T>.

Exceptions

Type	Condition
NotSupportedException	The ICollection<T> is read-only.

Remove(TKey)

Removes the element with the specified key from the IDictionary<TKey, TValue>.

Declaration

public virtual bool Remove(TKey key)

Parameters

Type	Name	Description
TKey	key	The key of the element to remove.

Returns

Type	Description
bool	true if the element is successfully removed; otherwise, false. This method also returns false if key was not found in the original IDictionary<TKey, TValue>.

Exceptions

Type	Condition
ArgumentNullException	key is null.
NotSupportedException	The IDictionary<TKey, TValue> is read-only.

TryGetValue(TKey, out TValue)

Gets the value associated with the specified key.

Declaration

public virtual bool TryGetValue(TKey key, out TValue value)

Parameters

Type	Name	Description
TKey	key	The key whose value to get.
TValue	value	When this method returns, the value associated with the specified key, if the key is found; otherwise, the default value for the type of the value parameter. This parameter is passed uninitialized.

Returns

Type	Description
bool	true if the object that implements IDictionary<TKey, TValue> contains an element with the specified key; otherwise, false.

Exceptions

Type	Condition
ArgumentNullException	key is null.

Implements

IDictionary<TKey, TValue>

ICollection<T>

IEnumerable<T>

IEnumerable