Package org.apache.commons.pool2.impl

Class LinkedBlockingDeque<E>

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      boolean add​(E e)
      void addFirst​(E e)
      void addLast​(E e)
      void clear()
      Atomically removes all of the elements from this deque.
      boolean contains​(Object o)
      Returns true if this deque contains the specified element.
      Iterator<E> descendingIterator()
      int drainTo​(Collection<? super E> c)
      Drains the queue to the specified collection.
      int drainTo​(Collection<? super E> c, int maxElements)
      Drains no more than the specified number of elements from the queue to the specified collection.
      E element()
      Retrieves, but does not remove, the head of the queue represented by this deque.
      E getFirst()
      E getLast()
      int getTakeQueueLength()
      Gets the length of the queue of threads waiting to take instances from this deque.
      boolean hasTakeWaiters()
      Returns true if there are threads waiting to take instances from this deque.
      void interuptTakeWaiters()
      Interrupts the threads currently waiting to take an object from the pool.
      Iterator<E> iterator()
      Returns an iterator over the elements in this deque in proper sequence.
      boolean offer​(E e)
      boolean offer​(E e, long timeout, TimeUnit unit)
      Links the provided element as the last in the queue, waiting up to the specified time to do so if the queue is full.
      (package private) boolean offer​(E e, Duration timeout)
      Links the provided element as the last in the queue, waiting up to the specified time to do so if the queue is full.
      boolean offerFirst​(E e)
      boolean offerFirst​(E e, long timeout, TimeUnit unit)
      Links the provided element as the first in the queue, waiting up to the specified time to do so if the queue is full.
      boolean offerFirst​(E e, Duration timeout)
      Links the provided element as the first in the queue, waiting up to the specified time to do so if the queue is full.
      boolean offerLast​(E e)
      boolean offerLast​(E e, long timeout, TimeUnit unit)
      Links the provided element as the last in the queue, waiting up to the specified time to do so if the queue is full.
      (package private) boolean offerLast​(E e, Duration timeout)
      Links the provided element as the last in the queue, waiting up to the specified time to do so if the queue is full.
      E peek()  
      E peekFirst()  
      E peekLast()  
      E poll()  
      E poll​(long timeout, TimeUnit unit)
      Unlinks the first element in the queue, waiting up to the specified time to do so if the queue is empty.
      (package private) E poll​(Duration timeout)
      Unlinks the first element in the queue, waiting up to the specified time to do so if the queue is empty.
      E pollFirst()  
      E pollFirst​(long timeout, TimeUnit unit)
      Unlinks the first element in the queue, waiting up to the specified time to do so if the queue is empty.
      (package private) E pollFirst​(Duration timeout)
      Unlinks the first element in the queue, waiting up to the specified time to do so if the queue is empty.
      E pollLast()  
      E pollLast​(long timeout, TimeUnit unit)
      Unlinks the last element in the queue, waiting up to the specified time to do so if the queue is empty.
      E pollLast​(Duration timeout)
      Unlinks the last element in the queue, waiting up to the specified time to do so if the queue is empty.
      E pop()
      void push​(E e)
      void put​(E e)
      Links the provided element as the last in the queue, waiting until there is space to do so if the queue is full.
      void putFirst​(E e)
      Links the provided element as the first in the queue, waiting until there is space to do so if the queue is full.
      void putLast​(E e)
      Links the provided element as the last in the queue, waiting until there is space to do so if the queue is full.
      int remainingCapacity()
      Returns the number of additional elements that this deque can ideally (in the absence of memory or resource constraints) accept without blocking.
      E remove()
      Retrieves and removes the head of the queue represented by this deque.
      boolean remove​(Object o)
      Removes the first occurrence of the specified element from this deque.
      E removeFirst()
      boolean removeFirstOccurrence​(Object o)  
      E removeLast()
      boolean removeLastOccurrence​(Object o)  
      int size()
      Returns the number of elements in this deque.
      E take()
      Unlinks the first element in the queue, waiting until there is an element to unlink if the queue is empty.
      E takeFirst()
      Unlinks the first element in the queue, waiting until there is an element to unlink if the queue is empty.
      E takeLast()
      Unlinks the last element in the queue, waiting until there is an element to unlink if the queue is empty.
      Object[] toArray()
      Returns an array containing all of the elements in this deque, in proper sequence (from first to last element).
      <T> T[] toArray​(T[] a)
      String toString()  

    • Constructor Detail

      • LinkedBlockingDeque

        public LinkedBlockingDeque()
        Creates a LinkedBlockingDeque with a capacity of Integer.MAX_VALUE.

      • LinkedBlockingDeque

        public LinkedBlockingDeque​(boolean fairness)
        Creates a LinkedBlockingDeque with a capacity of Integer.MAX_VALUE and the given fairness policy.
        Parameters:
        fairness - true means threads waiting on the deque should be served as if waiting in a FIFO request queue

      • LinkedBlockingDeque

        public LinkedBlockingDeque​(Collection<? extends E> c)
        Creates a LinkedBlockingDeque with a capacity of Integer.MAX_VALUE, 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

      • LinkedBlockingDeque

        public LinkedBlockingDeque​(int capacity)
        Creates a LinkedBlockingDeque with the given (fixed) capacity.
        Parameters:
        capacity - the capacity of this deque
        Throws:
        IllegalArgumentException - if capacity is less than 1

      • LinkedBlockingDeque

        public LinkedBlockingDeque​(int capacity,
                           boolean fairness)
        Creates a LinkedBlockingDeque with the given (fixed) capacity and fairness policy.
        Parameters:
        capacity - the capacity of this deque
        fairness - true means threads waiting on the deque should be served as if waiting in a FIFO request queue
        Throws:
        IllegalArgumentException - if capacity is less than 1

    • Method Detail

      • addFirst

        public void addFirst​(E e)
        Specified by:
        addFirst in interface Deque<E>

      • addLast

        public void addLast​(E e)
        Specified by:
        addLast in interface Deque<E>

      • clear

        public void clear()
        Atomically removes all of the elements from this deque. The deque will be empty after this call returns.
        Specified by:
        clear in interface Collection<E>
        Overrides:
        clear in class AbstractQueue<E>

      • contains

        public boolean contains​(Object o)
        Returns true if this deque contains the specified element. More formally, returns true if and only 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 - object to be checked for containment in this deque
        Returns:
        true if this deque contains the specified element

      • drainTo

        public int drainTo​(Collection<? super E> c)
        Drains the queue to the specified collection.
        Parameters:
        c - The collection to add the elements to
        Returns:
        number of elements added to the collection
        Throws:
        UnsupportedOperationException - if the add operation is not supported by the specified collection
        ClassCastException - if the class of the elements held by this collection prevents them from being added to the specified collection
        NullPointerException - if c is null
        IllegalArgumentException - if c is this instance

      • drainTo

        public int drainTo​(Collection<? super E> c,
                   int maxElements)
        Drains no more than the specified number of elements from the queue to the specified collection.
        Parameters:
        c - collection to add the elements to
        maxElements - maximum number of elements to remove from the queue
        Returns:
        number of elements added to the collection
        Throws:
        UnsupportedOperationException - if the add operation is not supported by the specified collection
        ClassCastException - if the class of the elements held by this collection prevents them from being added to the specified collection
        NullPointerException - if c is null
        IllegalArgumentException - if c is this instance

      • element

        public E element()
        Retrieves, but does not remove, the head of the queue represented by this deque. This method differs from peek only in that it throws an exception if this deque is empty.

        This method is equivalent to getFirst.

        Specified by:
        element in interface Deque<E>
        Specified by:
        element in interface Queue<E>
        Overrides:
        element in class AbstractQueue<E>
        Returns:
        the head of the queue represented by this deque
        Throws:
        NoSuchElementException - if this deque is empty

      • getFirst

        public E getFirst()
        Specified by:
        getFirst in interface Deque<E>

      • getLast

        public E getLast()
        Specified by:
        getLast in interface Deque<E>

      • getTakeQueueLength

        public int getTakeQueueLength()
        Gets the length of the queue of threads waiting to take instances from this deque. See disclaimer on accuracy in ReentrantLock.getWaitQueueLength(Condition).
        Returns:
        number of threads waiting on this deque's notEmpty condition.

      • hasTakeWaiters

        public boolean hasTakeWaiters()
        Returns true if there are threads waiting to take instances from this deque. See disclaimer on accuracy in ReentrantLock.hasWaiters(Condition).
        Returns:
        true if there is at least one thread waiting on this deque's notEmpty condition.

      • iterator

        public Iterator<E> iterator()
        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

      • offer

        public boolean offer​(E e)
        Specified by:
        offer in interface Deque<E>
        Specified by:
        offer in interface Queue<E>

      • offer

        public boolean offer​(E e,
                     long timeout,
                     TimeUnit unit)
              throws InterruptedException
        Links the provided element as the last in the queue, waiting up to the specified time to do so if the queue is full.

        This method is equivalent to offerLast(Object, long, TimeUnit)

        Parameters:
        e - element to link
        timeout - length of time to wait
        unit - units that timeout is expressed in
        Returns:
        true if successful, otherwise false
        Throws:
        NullPointerException - if e is null
        InterruptedException - if the thread is interrupted whilst waiting for space

      • offerFirst

        public boolean offerFirst​(E e)
        Specified by:
        offerFirst in interface Deque<E>

      • offerFirst

        public boolean offerFirst​(E e,
                          Duration timeout)
                   throws InterruptedException
        Links the provided element as the first in the queue, waiting up to the specified time to do so if the queue is full.
        Parameters:
        e - element to link
        timeout - length of time to wait
        Returns:
        true if successful, otherwise false
        Throws:
        NullPointerException - if e is null
        InterruptedException - if the thread is interrupted whilst waiting for space

      • offerFirst

        public boolean offerFirst​(E e,
                          long timeout,
                          TimeUnit unit)
                   throws InterruptedException
        Links the provided element as the first in the queue, waiting up to the specified time to do so if the queue is full.
        Parameters:
        e - element to link
        timeout - length of time to wait
        unit - units that timeout is expressed in
        Returns:
        true if successful, otherwise false
        Throws:
        NullPointerException - if e is null
        InterruptedException - if the thread is interrupted whilst waiting for space

      • offerLast

        public boolean offerLast​(E e)
        Specified by:
        offerLast in interface Deque<E>

      • offerLast

        boolean offerLast​(E e,
                  Duration timeout)
           throws InterruptedException
        Links the provided element as the last in the queue, waiting up to the specified time to do so if the queue is full.
        Parameters:
        e - element to link
        timeout - length of time to wait
        Returns:
        true if successful, otherwise false
        Throws:
        NullPointerException - if e is null
        InterruptedException - if the thread is interrupted whist waiting for space

      • offerLast

        public boolean offerLast​(E e,
                         long timeout,
                         TimeUnit unit)
                  throws InterruptedException
        Links the provided element as the last in the queue, waiting up to the specified time to do so if the queue is full.
        Parameters:
        e - element to link
        timeout - length of time to wait
        unit - units that timeout is expressed in
        Returns:
        true if successful, otherwise false
        Throws:
        NullPointerException - if e is null
        InterruptedException - if the thread is interrupted whist waiting for space

      • peek

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

      • peekFirst

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

      • peekLast

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

      • poll

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

      • poll

        public E poll​(long timeout,
              TimeUnit unit)
       throws InterruptedException
        Unlinks the first element in the queue, waiting up to the specified time to do so if the queue is empty.

        This method is equivalent to pollFirst(long, TimeUnit).

        Parameters:
        timeout - length of time to wait
        unit - units that timeout is expressed in
        Returns:
        the unlinked element
        Throws:
        InterruptedException - if the current thread is interrupted

      • pollFirst

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

      • pollFirst

        E pollFirst​(Duration timeout)
     throws InterruptedException
        Unlinks the first element in the queue, waiting up to the specified time to do so if the queue is empty.
        Parameters:
        timeout - length of time to wait
        Returns:
        the unlinked element
        Throws:
        InterruptedException - if the current thread is interrupted

      • pollFirst

        public E pollFirst​(long timeout,
                   TimeUnit unit)
            throws InterruptedException
        Unlinks the first element in the queue, waiting up to the specified time to do so if the queue is empty.
        Parameters:
        timeout - length of time to wait
        unit - units that timeout is expressed in
        Returns:
        the unlinked element
        Throws:
        InterruptedException - if the current thread is interrupted

      • pollLast

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

      • pollLast

        public E pollLast​(Duration timeout)
           throws InterruptedException
        Unlinks the last element in the queue, waiting up to the specified time to do so if the queue is empty.
        Parameters:
        timeout - length of time to wait
        Returns:
        the unlinked element
        Throws:
        InterruptedException - if the current thread is interrupted

      • pollLast

        public E pollLast​(long timeout,
                  TimeUnit unit)
           throws InterruptedException
        Unlinks the last element in the queue, waiting up to the specified time to do so if the queue is empty.
        Parameters:
        timeout - length of time to wait
        unit - units that timeout is expressed in
        Returns:
        the unlinked element
        Throws:
        InterruptedException - if the current thread is interrupted

      • pop

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

      • push

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

      • putFirst

        public void putFirst​(E e)
              throws InterruptedException
        Links the provided element as the first in the queue, waiting until there is space to do so if the queue is full.
        Parameters:
        e - element to link
        Throws:
        NullPointerException - if e is null
        InterruptedException - if the thread is interrupted whilst waiting for space

      • putLast

        public void putLast​(E e)
             throws InterruptedException
        Links the provided element as the last in the queue, waiting until there is space to do so if the queue is full.
        Parameters:
        e - element to link
        Throws:
        NullPointerException - if e is null
        InterruptedException - if the thread is interrupted whilst waiting for space

      • remainingCapacity

        public int remainingCapacity()
        Returns the number of additional elements that this deque can ideally (in the absence of memory or resource constraints) accept without blocking. This is always equal to the initial capacity of this deque less the current size of this deque.

        Note that you cannot always tell if an attempt to insert an element will succeed by inspecting remainingCapacity because it may be the case that another thread is about to insert or remove an element.

        Returns:
        The number of additional elements the queue is able to accept

      • remove

        public E remove()
        Retrieves and removes the head of the queue represented by this deque. This method differs from poll only in that it throws an exception if this deque is empty.

        This method is equivalent to removeFirst.

        Specified by:
        remove in interface Deque<E>
        Specified by:
        remove in interface Queue<E>
        Overrides:
        remove in class AbstractQueue<E>
        Returns:
        the head of the queue represented by this deque
        Throws:
        NoSuchElementException - if this deque is empty

      • remove

        public boolean remove​(Object o)
        Removes the first occurrence of the specified element from this deque. If the deque does not contain the element, it is unchanged. More formally, removes the first element e such that o.equals(e) (if such an element exists). Returns true if this deque contained the specified element (or equivalently, if this deque changed as a result of the call).

        This method is equivalent to removeFirstOccurrence.

        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 this deque changed as a result of the call

      • removeLast

        public E removeLast()
        Specified by:
        removeLast in interface Deque<E>

      • size

        public int size()
        Returns the number of elements in this deque.
        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

      • take

        public E take()
       throws InterruptedException
        Unlinks the first element in the queue, waiting until there is an element to unlink if the queue is empty.

        This method is equivalent to takeFirst().

        Returns:
        the unlinked element
        Throws:
        InterruptedException - if the current thread is interrupted

      • takeFirst

        public E takeFirst()
            throws InterruptedException
        Unlinks the first element in the queue, waiting until there is an element to unlink if the queue is empty.
        Returns:
        the unlinked element
        Throws:
        InterruptedException - if the current thread is interrupted

      • takeLast

        public E takeLast()
           throws InterruptedException
        Unlinks the last element in the queue, waiting until there is an element to unlink if the queue is empty.
        Returns:
        the unlinked element
        Throws:
        InterruptedException - if the current thread is interrupted

      • toArray

        public Object[] toArray()
        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