Package com.mongodb.internal.connection

Class ConcurrentLinkedDeque<E>

java.lang.Object

java.util.AbstractCollection<E>

com.mongodb.internal.connection.ConcurrentLinkedDeque<E>

Type Parameters:

E - the type of elements held in this collection

All Implemented Interfaces:

java.io.Serializable, java.lang.Iterable<E>, java.util.Collection<E>, java.util.Deque<E>, java.util.Queue<E>

@Deprecated(since="2021-05-27")
public class ConcurrentLinkedDeque<E>
extends java.util.AbstractCollection<E>
implements java.util.Deque<E>, java.io.Serializable

Deprecated.

Usage of this API is not supported in AEM as a Cloud Service.

A concurrent linked-list implementation of a Deque (double-ended queue).

This class should not be considered a part of the public API.

Concurrent insertion, removal, and access operations execute safely across multiple threads. Iterators are weakly consistent, returning elements reflecting the state of the deque at some point at or since the creation of the iterator. They do not throw ConcurrentModificationException, and may proceed concurrently with other operations.

This class and its iterators implement all of the optional methods of the Collection and Iterator interfaces. Like most other concurrent collection implementations, this class does not permit the use of null elements. because some null arguments and return values cannot be reliably distinguished from the absence of elements. Arbitrarily, the Collection.remove(java.lang.Object) method is mapped to removeFirstOccurrence, and Collection.add(E) is mapped to addLast.

Beware that, unlike in most collections, the size method is NOT a constant-time operation. Because of the asynchronous nature of these deques, determining the current number of elements requires a traversal of the elements.

This class is Serializable, but relies on default serialization mechanisms. Usually, it is a better idea for any serializable class using a ConcurrentLinkedDeque to instead serialize a snapshot of the elements obtained by method toArray.

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static interface	ConcurrentLinkedDeque.RemovalReportingIterator<E>	Deprecated.

Constructor Summary

Constructors

Constructor	Description
ConcurrentLinkedDeque()	Deprecated. Constructs an empty deque.
ConcurrentLinkedDeque(java.util.Collection<? extends E> c)	Deprecated. Constructs a deque initially containing the elements of the given collection, added in traversal order of the collection's iterator.

Method Summary

Modifier and Type	Method	Description
boolean	add(E e)	Deprecated. Inserts the specified element at the tail of this deque.
boolean	addAll(java.util.Collection<? extends E> c)	Deprecated. Appends all of the elements in the specified collection to the end of this deque, in the order that they are returned by the specified collection's iterator.
void	addFirst(E e)	Deprecated. Inserts the specified element at the front of this deque.
void	addLast(E e)	Deprecated. Inserts the specified element at the end of this deque.
void	clear()	Deprecated. Removes all of the elements from this deque.
boolean	contains(java.lang.Object o)	Deprecated. Returns true if this deque contains at least one element e such that o.equals(e).
java.util.Iterator<E>	descendingIterator()	Deprecated. Not yet implemented.
E	element()	Deprecated.
E	getFirst()	Deprecated.
E	getLast()	Deprecated.
boolean	isEmpty()	Deprecated. Returns true if this collection contains no elements.
ConcurrentLinkedDeque.RemovalReportingIterator<E>	iterator()	Deprecated. Returns an iterator over the elements in this deque in proper sequence.
boolean	offer(E e)	Deprecated. Inserts the specified element at the tail of this queue.
boolean	offerFirst(E e)	Deprecated. Inserts the specified element at the front of this deque.
boolean	offerLast(E e)	Deprecated. Inserts the specified element at the end of this deque.
E	peek()	Deprecated.
E	peekFirst()	Deprecated.
E	peekLast()	Deprecated.
E	poll()	Deprecated.
E	pollFirst()	Deprecated.
E	pollLast()	Deprecated.
E	pop()	Deprecated.
void	push(E e)	Deprecated.
E	remove()	Deprecated.
boolean	remove(java.lang.Object o)	Deprecated. Removes the first element e such that o.equals(e), if such an element exists in this deque.
E	removeFirst()	Deprecated.
boolean	removeFirstOccurrence(java.lang.Object o)	Deprecated. Removes the first element e such that o.equals(e), if such an element exists in this deque.
E	removeLast()	Deprecated.
boolean	removeLastOccurrence(java.lang.Object o)	Deprecated. Removes the last element e such that o.equals(e), if such an element exists in this deque.
int	size()	Deprecated. Returns the number of elements in this deque.
java.lang.Object[]	toArray()	Deprecated. Returns an array containing all of the elements in this deque, in proper sequence (from first to last element).
<T> T[]	toArray(T[] a)	Deprecated. Returns an array containing all of the elements in this deque, in proper sequence (from first to last element); the runtime type of the returned array is that of the specified array.

Methods inherited from class java.util.AbstractCollection

containsAll, removeAll, retainAll, toString

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.util.Collection

containsAll, equals, hashCode, parallelStream, removeAll, removeIf, retainAll, spliterator, stream, toArray

Methods inherited from interface java.lang.Iterable

forEach

Constructor Detail

ConcurrentLinkedDeque

public ConcurrentLinkedDeque()

Deprecated.

Constructs an empty deque.

ConcurrentLinkedDeque

public ConcurrentLinkedDeque(java.util.Collection<? extends E> c)

Deprecated.

Constructs a deque initially containing the elements of the given collection, added in traversal order of the collection's iterator.

Parameters:

c - the collection of elements to initially contain

Throws:

java.lang.NullPointerException - if the specified collection or any of its elements are null

Method Detail

addFirst

public void addFirst(E e)

Deprecated.

Inserts the specified element at the front of this deque.

Specified by:

addFirst in interface java.util.Deque<E>

Throws:

java.lang.NullPointerException

addLast

public void addLast(E e)

Deprecated.

Inserts the specified element at the end of this deque. This is identical in function to the add method.

Specified by:

addLast in interface java.util.Deque<E>

Throws:

java.lang.NullPointerException

offerFirst

public boolean offerFirst(E e)

Deprecated.

Inserts the specified element at the front of this deque.

Specified by:

offerFirst in interface java.util.Deque<E>

Returns:

true always

Throws:

java.lang.NullPointerException

offerLast

public boolean offerLast(E e)

Deprecated.

Inserts the specified element at the end of this deque.

This method is equivalent to add(E).

Specified by:

offerLast in interface java.util.Deque<E>

Returns:

true always

Throws:

java.lang.NullPointerException

peekFirst

public E peekFirst()

Deprecated.

Specified by:

peekFirst in interface java.util.Deque<E>

peekLast

public E peekLast()

Deprecated.

Specified by:

peekLast in interface java.util.Deque<E>

getFirst

public E getFirst()

Deprecated.

Specified by:

getFirst in interface java.util.Deque<E>

Throws:

java.util.NoSuchElementException

getLast

public E getLast()

Deprecated.

Specified by:

getLast in interface java.util.Deque<E>

Throws:

java.util.NoSuchElementException

pollFirst

public E pollFirst()

Deprecated.

Specified by:

pollFirst in interface java.util.Deque<E>

pollLast

public E pollLast()

Deprecated.

Specified by:

pollLast in interface java.util.Deque<E>

removeFirst

public E removeFirst()

Deprecated.

Specified by:

removeFirst in interface java.util.Deque<E>

Throws:

java.util.NoSuchElementException

removeLast

public E removeLast()

Deprecated.

Specified by:

removeLast in interface java.util.Deque<E>

Throws:

java.util.NoSuchElementException

offer

public boolean offer(E e)

Deprecated.

Inserts the specified element at the tail of this queue.

Specified by:

offer in interface java.util.Deque<E>

Specified by:

offer in interface java.util.Queue<E>

Returns:

true (as specified by Queue.offer)

Throws:

java.lang.NullPointerException - if the specified element is null

add

public boolean add(E e)

Deprecated.

Inserts the specified element at the tail of this deque.

Specified by:

add in interface java.util.Collection<E>

Specified by:

add in interface java.util.Deque<E>

Specified by:

add in interface java.util.Queue<E>

Overrides:

add in class java.util.AbstractCollection<E>

Returns:

true (as specified by Collection.add(E))

Throws:

java.lang.NullPointerException - if the specified element is null

poll

public E poll()

Deprecated.

Specified by:

poll in interface java.util.Deque<E>

Specified by:

poll in interface java.util.Queue<E>

remove

public E remove()

Deprecated.

Specified by:

remove in interface java.util.Deque<E>

Specified by:

remove in interface java.util.Queue<E>

peek

public E peek()

Deprecated.

Specified by:

peek in interface java.util.Deque<E>

Specified by:

peek in interface java.util.Queue<E>

element

public E element()

Deprecated.

Specified by:

element in interface java.util.Deque<E>

Specified by:

element in interface java.util.Queue<E>

push

public void push(E e)

Deprecated.

Specified by:

push in interface java.util.Deque<E>

pop

public E pop()

Deprecated.

Specified by:

pop in interface java.util.Deque<E>

removeFirstOccurrence

public boolean removeFirstOccurrence(java.lang.Object o)

Deprecated.

Removes the first element e such that o.equals(e), if such an element exists in this deque. If the deque does not contain the element, it is unchanged.

Specified by:

removeFirstOccurrence in interface java.util.Deque<E>

Parameters:

o - element to be removed from this deque, if present

Returns:

true if the deque contained the specified element

Throws:

java.lang.NullPointerException - if the specified element is null

removeLastOccurrence

public boolean removeLastOccurrence(java.lang.Object o)

Deprecated.

Removes the last element e such that o.equals(e), if such an element exists in this deque. If the deque does not contain the element, it is unchanged.

Specified by:

removeLastOccurrence in interface java.util.Deque<E>

Parameters:

o - element to be removed from this deque, if present

Returns:

true if the deque contained the specified element

Throws:

java.lang.NullPointerException - if the specified element is null

contains

public boolean contains(java.lang.Object o)

Deprecated.

Returns true if this deque contains at least one element e such that o.equals(e).

Specified by:

contains in interface java.util.Collection<E>

Specified by:

contains in interface java.util.Deque<E>

Overrides:

contains in class java.util.AbstractCollection<E>

Parameters:

o - element whose presence in this deque is to be tested

Returns:

true if this deque contains the specified element

isEmpty

public boolean isEmpty()

Deprecated.

Returns true if this collection contains no elements.

Specified by:

isEmpty in interface java.util.Collection<E>

Overrides:

isEmpty in class java.util.AbstractCollection<E>

Returns:

true if this collection contains no elements

size

public int size()

Deprecated.

Returns the number of elements in this deque. If this deque contains more than Integer.MAX_VALUE elements, it returns Integer.MAX_VALUE.

Beware that, unlike in most collections, this method is NOT a constant-time operation. Because of the asynchronous nature of these deques, determining the current number of elements requires traversing them all to count them. Additionally, it is possible for the size to change during execution of this method, in which case the returned result will be inaccurate. Thus, this method is typically not very useful in concurrent applications.

Specified by:

size in interface java.util.Collection<E>

Specified by:

size in interface java.util.Deque<E>

Specified by:

size in class java.util.AbstractCollection<E>

Returns:

the number of elements in this deque

remove

public boolean remove(java.lang.Object o)

Deprecated.

Removes the first element e such that o.equals(e), if such an element exists in this deque. If the deque does not contain the element, it is unchanged.

Specified by:

remove in interface java.util.Collection<E>

Specified by:

remove in interface java.util.Deque<E>

Overrides:

remove in class java.util.AbstractCollection<E>

Parameters:

o - element to be removed from this deque, if present

Returns:

true if the deque contained the specified element

Throws:

java.lang.NullPointerException - if the specified element is null

addAll

public boolean addAll(java.util.Collection<? extends E> c)

Deprecated.

Appends all of the elements in the specified collection to the end of this deque, in the order that they are returned by the specified collection's iterator. The behavior of this operation is undefined if the specified collection is modified while the operation is in progress. (This implies that the behavior of this call is undefined if the specified Collection is this deque, and this deque is nonempty.)

Specified by:

addAll in interface java.util.Collection<E>

Specified by:

addAll in interface java.util.Deque<E>

Overrides:

addAll in class java.util.AbstractCollection<E>

Parameters:

c - the elements to be inserted into this deque

Returns:

true if this deque changed as a result of the call

Throws:

java.lang.NullPointerException - if c or any element within it is null

clear

public void clear()

Deprecated.

Removes all of the elements from this deque.

Specified by:

clear in interface java.util.Collection<E>

Overrides:

clear in class java.util.AbstractCollection<E>

toArray

public java.lang.Object[] toArray()

Deprecated.

Returns an array containing all of the elements in this deque, in proper sequence (from first to last element).

The returned array will be "safe" in that no references to it are maintained by this deque. (In other words, this method must allocate a new array). The caller is thus free to modify the returned array.

This method acts as bridge between array-based and collection-based APIs.

Specified by:

toArray in interface java.util.Collection<E>

Overrides:

toArray in class java.util.AbstractCollection<E>

Returns:

an array containing all of the elements in this deque

toArray

public <T> T[] toArray(T[] a)

Deprecated.

Returns an array containing all of the elements in this deque, in proper sequence (from first to last element); the runtime type of the returned array is that of the specified array. If the deque fits in the specified array, it is returned therein. Otherwise, a new array is allocated with the runtime type of the specified array and the size of this deque.

If this deque fits in the specified array with room to spare (i.e., the array has more elements than this deque), the element in the array immediately following the end of the deque is set to null.

Like the toArray() method, this method acts as bridge between array-based and collection-based APIs. Further, this method allows precise control over the runtime type of the output array, and may, under certain circumstances, be used to save allocation costs.

Suppose x is a deque known to contain only strings. The following code can be used to dump the deque into a newly allocated array of String:

     String[] y = x.toArray(new String[0]);

Note that toArray(new Object[0]) is identical in function to toArray().

Specified by:

toArray in interface java.util.Collection<E>

Overrides:

toArray in class java.util.AbstractCollection<E>

Parameters:

a - the array into which the elements of the deque are to be stored, if it is big enough; otherwise, a new array of the same runtime type is allocated for this purpose

Returns:

an array containing all of the elements in this deque

Throws:

java.lang.ArrayStoreException - if the runtime type of the specified array is not a supertype of the runtime type of every element in this deque

java.lang.NullPointerException - if the specified array is null

iterator

public ConcurrentLinkedDeque.RemovalReportingIterator<E> iterator()

Deprecated.

Returns an iterator over the elements in this deque in proper sequence. The elements will be returned in order from first (head) to last (tail). The returned Iterator is a "weakly consistent" iterator that will never throw ConcurrentModificationException, and guarantees to traverse elements as they existed upon construction of the iterator, and may (but is not guaranteed to) reflect any modifications subsequent to construction.

Specified by:

iterator in interface java.util.Collection<E>

Specified by:

iterator in interface java.util.Deque<E>

Specified by:

iterator in interface java.lang.Iterable<E>

Specified by:

iterator in class java.util.AbstractCollection<E>

Returns:

an iterator over the elements in this deque in proper sequence

descendingIterator

public java.util.Iterator<E> descendingIterator()

Deprecated.

Not yet implemented.

Specified by:

descendingIterator in interface java.util.Deque<E>