Package com.mongodb.internal.connection

Class ConcurrentLinkedDeque<E>

  • Type Parameters:
    E - the type of elements held in this collection
    All Implemented Interfaces:
    Serializable, Iterable<E>, Collection<E>, Deque<E>, Queue<E>
    @Deprecated(since="2021-05-27")
public class ConcurrentLinkedDeque<E>
extends AbstractCollection<E>
implements Deque<E>, 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

    • Constructor Detail

      • ConcurrentLinkedDeque

        public ConcurrentLinkedDeque()
        Deprecated.
        Constructs an empty deque.

      • ConcurrentLinkedDeque

        public ConcurrentLinkedDeque​(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:
        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 Deque<E>
        Throws:
        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 Deque<E>
        Throws:
        NullPointerException

      • offerFirst

        public boolean offerFirst​(E e)
        Deprecated.
        Inserts the specified element at the front of this deque.
        Specified by:
        offerFirst in interface Deque<E>
        Returns:
        true always
        Throws:
        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 Deque<E>
        Returns:
        true always
        Throws:
        NullPointerException

      • peekFirst

        public E peekFirst()
        Deprecated.
        Specified by:
        peekFirst in interface Deque<E>

      • peekLast

        public E peekLast()
        Deprecated.
        Specified by:
        peekLast in interface Deque<E>

      • pollFirst

        public E pollFirst()
        Deprecated.
        Specified by:
        pollFirst in interface Deque<E>

      • pollLast

        public E pollLast()
        Deprecated.
        Specified by:
        pollLast in interface Deque<E>

      • offer

        public boolean offer​(E e)
        Deprecated.
        Inserts the specified element at the tail of this queue.
        Specified by:
        offer in interface Deque<E>
        Specified by:
        offer in interface Queue<E>
        Returns:
        true (as specified by Queue.offer)
        Throws:
        NullPointerException - if the specified element is null

      • poll

        public E poll()
        Deprecated.
        Specified by:
        poll in interface Deque<E>
        Specified by:
        poll in interface Queue<E>

      • remove

        public E remove()
        Deprecated.
        Specified by:
        remove in interface Deque<E>
        Specified by:
        remove in interface Queue<E>

      • peek

        public E peek()
        Deprecated.
        Specified by:
        peek in interface Deque<E>
        Specified by:
        peek in interface Queue<E>

      • push

        public void push​(E e)
        Deprecated.
        Specified by:
        push in interface Deque<E>

      • pop

        public E pop()
        Deprecated.
        Specified by:
        pop in interface Deque<E>

      • removeFirstOccurrence

        public boolean removeFirstOccurrence​(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 Deque<E>
        Parameters:
        o - element to be removed from this deque, if present
        Returns:
        true if the deque contained the specified element
        Throws:
        NullPointerException - if the specified element is null

      • removeLastOccurrence

        public boolean removeLastOccurrence​(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 Deque<E>
        Parameters:
        o - element to be removed from this deque, if present
        Returns:
        true if the deque contained the specified element
        Throws:
        NullPointerException - if the specified element is null

      • contains

        public boolean contains​(Object o)
        Deprecated.
        Returns true if this deque contains at least one element e such that o.equals(e).
        Specified by:
        contains in interface Collection<E>
        Specified by:
        contains in interface Deque<E>
        Overrides:
        contains in class 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 Collection<E>
        Overrides:
        isEmpty in class 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 Collection<E>
        Specified by:
        size in interface Deque<E>
        Specified by:
        size in class AbstractCollection<E>
        Returns:
        the number of elements in this deque

      • remove

        public boolean remove​(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 Collection<E>
        Specified by:
        remove in interface Deque<E>
        Overrides:
        remove in class AbstractCollection<E>
        Parameters:
        o - element to be removed from this deque, if present
        Returns:
        true if the deque contained the specified element
        Throws:
        NullPointerException - if the specified element is null

      • addAll

        public boolean addAll​(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 Collection<E>
        Specified by:
        addAll in interface Deque<E>
        Overrides:
        addAll in class 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:
        NullPointerException - if c or any element within it is null

      • toArray

        public 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 Collection<E>
        Overrides:
        toArray in class 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 Collection<E>
        Overrides:
        toArray in class 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:
        ArrayStoreException - if the runtime type of the specified array is not a supertype of the runtime type of every element in this deque
        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 Collection<E>
        Specified by:
        iterator in interface Deque<E>
        Specified by:
        iterator in interface Iterable<E>
        Specified by:
        iterator in class AbstractCollection<E>
        Returns:
        an iterator over the elements in this deque in proper sequence