jdk.util.concurrent.DelayQueue — clojure-interop/java.util.concurrent 1.0.5

An unbounded java.util.concurrent.blocking queue of Delayed elements, in which an element can only be taken when its delay has expired. The head of the queue is that Delayed element whose delay expired furthest in the past. If no delay has expired there is no head and poll will return null. Expiration occurs when an element's getDelay(TimeUnit.NANOSECONDS) method returns a value less than or equal to zero. Even though unexpired elements cannot be removed using take or poll, they are otherwise treated as normal elements. For example, the size method returns the count of both expired and unexpired elements. This queue does not permit null elements.

This class and its iterator implement all of the optional methods of the Collection and Iterator interfaces. The Iterator provided in method iterator() is not guaranteed to traverse the elements of the DelayQueue in any particular order.

This class is a member of the

Java Collections Framework.

->delay-queue clj

(->delay-queue)

(->delay-queue c)

Constructor.

Creates a DelayQueue initially containing the elements of the given collection of Delayed instances.

c - the collection of elements to initially contain - java.util.Collection

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

add clj

(add this e)

Inserts the specified element into this delay queue.

e - the element to add - E

returns: true (as specified by Collection.add(E)) - boolean

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

clear clj

(clear this)

Atomically removes all of the elements from this delay queue. The queue will be empty after this call returns. Elements with an unexpired delay are not waited for; they are simply discarded from the queue.

drain-to clj

(drain-to this c)

(drain-to this c max-elements)

Description copied from interface: BlockingQueue

c - the collection to transfer elements into - java.util.Collection max-elements - the maximum number of elements to transfer - int

returns: the number of elements transferred - int

throws: java.lang.UnsupportedOperationException - if addition of elements is not supported by the specified collection

iterator clj

(iterator this)

Returns an iterator over all the elements (both expired and unexpired) in this queue. The iterator does not return the elements in any particular order.

The returned iterator is weakly consistent.

returns: an iterator over the elements in this queue - java.util.Iterator<E>

offer clj

(offer this e)

(offer this e timeout unit)

Inserts the specified element into this delay queue. As the queue is unbounded this method will never block.

e - the element to add - E timeout - This parameter is ignored as the method never blocks - long unit - This parameter is ignored as the method never blocks - java.util.concurrent.TimeUnit

returns: true - boolean

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

peek clj

(peek this)

Retrieves, but does not remove, the head of this queue, or returns null if this queue is empty. Unlike poll, if no expired elements are available in the queue, this method returns the element that will expire next, if one exists.

returns: the head of this queue, or null if this queue is empty - E

poll clj

(poll this)

(poll this timeout unit)

Retrieves and removes the head of this queue, waiting if necessary until an element with an expired delay is available on this queue, or the specified wait time expires.

timeout - how long to wait before giving up, in units of unit - long unit - a TimeUnit determining how to interpret the timeout parameter - java.util.concurrent.TimeUnit

returns: the head of this queue, or null if the specified waiting time elapses before an element with an expired delay becomes available - E

throws: java.lang.InterruptedException - if interrupted while waiting

put clj

(put this e)

Inserts the specified element into this delay queue. As the queue is unbounded this method will never block.

e - the element to add - E

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

remaining-capacity clj

(remaining-capacity this)

Always returns Integer.MAX_VALUE because a DelayQueue is not capacity constrained.

returns: Integer.MAX_VALUE - int

remove clj

(remove this o)

Removes a single instance of the specified element from this queue, if it is present, whether or not it has expired.

o - element to be removed from this collection, if present - java.lang.Object

returns: true if an element was removed as a result of this call - boolean

size clj

(size this)

Description copied from interface: Collection

returns: the number of elements in this collection - int

take clj

(take this)

Retrieves and removes the head of this queue, waiting if necessary until an element with an expired delay is available on this queue.

returns: the head of this queue - E

throws: java.lang.InterruptedException - if interrupted while waiting

to-array clj

(to-array this)

(to-array this a)

Returns an array containing all of the elements in this queue; the runtime type of the returned array is that of the specified array. The returned array elements are in no particular order. If the queue 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 queue.

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

The following code can be used to dump a delay queue into a newly allocated array of Delayed:

Delayed[] a = q.toArray(new Delayed[0]);

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

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

returns: an array containing all of the elements in this queue - <T> T[]

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 queue