Scala example source code file (SynchronizedQueue.scala)

This example Scala source code file (SynchronizedQueue.scala) is included in my "Source Code Warehouse" project. The intent of this project is to help you more easily find Scala source code examples by using tags.

All credit for the original source code belongs to scala-lang.org; I'm just trying to make examples easier to find. (For my Scala work, see my Scala examples and tutorials.)

Scala tags/keywords

a, any, boolean, consider, option, queue, seq, synchronization, traversableonce, unit

The SynchronizedQueue.scala Scala example source code

/*                     __                                               *\
**     ________ ___   / /  ___     Scala API                            **
**    / __/ __// _ | / /  / _ |    (c) 2003-2013, LAMP/EPFL             **
**  __\ \/ /__/ __ |/ /__/ __ |                                         **
** /____/\___/_/ |_/____/_/ | |                                         **
**                          |/                                          **
\*                                                                      */



package scala
package collection
package mutable


/** This is a synchronized version of the `Queue[T]` class. It
 *  implements a data structure that allows one to insert and retrieve
 *  elements in a first-in-first-out (FIFO) manner.
 *
 *  @tparam A     type of elements contained in this synchronized queue.
 *
 *  @author  Matthias Zenger
 *  @version 1.0, 03/05/2004
 *  @since   1
 *  @define Coll `SynchronizedQueue`
 *  @define coll synchronized queue
 */
@deprecated("Synchronization via selective overriding of methods is inherently unreliable.  Consider java.util.concurrent.ConcurrentLinkedQueue as an alternative.", "2.11.0")
class SynchronizedQueue[A] extends Queue[A] {
  /** Checks if the queue is empty.
   *
   *  @return true, iff there is no element in the queue.
   */
  override def isEmpty: Boolean = synchronized { super.isEmpty }

  /** Inserts a single element at the end of the queue.
   *
   *  @param  elem        the element to insert
   */
  override def +=(elem: A): this.type = synchronized[this.type] { super.+=(elem) }

  /** Adds all elements provided by a `TraversableOnce` object
   *  at the end of the queue. The elements are prepended in the order they
   *  are given out by the iterator.
   *
   *  @param  xs        a traversable object
   */
  override def ++=(xs: TraversableOnce[A]): this.type = synchronized[this.type] { super.++=(xs) }

  /** Adds all elements to the queue.
   *
   *  @param  elems       the elements to add.
   */
  override def enqueue(elems: A*): Unit = synchronized { super.++=(elems) }

  /** Returns the first element in the queue, and removes this element
   *  from the queue.
   *
   *  @return the first element of the queue.
   */
  override def dequeue(): A = synchronized { super.dequeue() }

  /** Returns the first element in the queue which satisfies the
   *  given predicate, and removes this element from the queue.
   *
   *  @param p   the predicate used for choosing the first element
   *  @return the first element of the queue for which p yields true
   */
  override def dequeueFirst(p: A => Boolean): Option[A] = synchronized { super.dequeueFirst(p) }

  /** Returns all elements in the queue which satisfy the
   *  given predicate, and removes those elements from the queue.
   *
   *  @param p   the predicate used for choosing elements
   *  @return    a sequence of all elements in the queue for which
   *             p yields true.
   */
  override def dequeueAll(p: A => Boolean): Seq[A] = synchronized { super.dequeueAll(p) }

  /** Returns the first element in the queue, or throws an error if there
   *  is no element contained in the queue.
   *
   *  @return the first element.
   */
  override def front: A = synchronized { super.front }

  /** Removes all elements from the queue. After this operation is completed,
   *  the queue will be empty.
   */
  override def clear(): Unit = synchronized { super.clear() }

  /** Checks if two queues are structurally identical.
   *
   *  @return true, iff both queues contain the same sequence of elements.
   */
  override def equals(that: Any): Boolean = synchronized { super.equals(that) }

  /** Returns a textual representation of a queue as a string.
   *
   *  @return the string representation of this queue.
   */
  override def toString() = synchronized { super.toString() }
}