LinkedTransferQueue
open class LinkedTransferQueue<E : Any!> : AbstractQueue<E>, TransferQueue<E>, Serializable
An unbounded TransferQueue based on linked nodes. This queue orders elements FIFO (first-in-first-out) with respect to any given producer. The head of the queue is that element that has been on the queue the longest time for some producer. The tail of the queue is that element that has been on the queue the shortest time for some producer.
Beware that, unlike in most collections, the size method is NOT a constant-time operation. Because of the asynchronous nature of these queues, determining the current number of elements requires a traversal of the elements, and so may report inaccurate results if this collection is modified during traversal. Additionally, the bulk operations addAll, removeAll, retainAll, containsAll, equals, and toArray are not guaranteed to be performed atomically. For example, an iterator operating concurrently with an addAll operation might view only some of the added elements.
This class and its iterator implement all of the optional methods of the Collection and Iterator interfaces.
Memory consistency effects: As with other concurrent collections, actions in a thread prior to placing an object into a LinkedTransferQueue happen-before actions subsequent to the access or removal of that element from the LinkedTransferQueue in another thread.
Summary
| Public constructors |
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Creates an initially empty LinkedTransferQueue.
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Creates a LinkedTransferQueue initially containing the elements of the given collection, added in traversal order of the collection's iterator.
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| Public methods |
| open Boolean |
Inserts the specified element at the tail of this queue.
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| open Boolean |
Returns true if this queue contains the specified element.
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| open Int |
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| open Int |
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| open Int |
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| open Boolean |
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| open Boolean |
Returns true if this queue contains no elements.
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| open MutableIterator<E> |
Returns an iterator over the elements in this queue in proper sequence.
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| open Boolean |
Inserts the specified element at the tail of this queue.
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| open Boolean |
Inserts the specified element at the tail of this queue.
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| open E? |
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| open E |
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| open E? |
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| open Unit |
Inserts the specified element at the tail of this queue.
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| open Int |
Always returns Integer.MAX_VALUE because a LinkedTransferQueue is not capacity constrained.
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| open Boolean |
Removes a single instance of the specified element from this queue, if it is present.
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| open Spliterator<E> |
Returns a Spliterator over the elements in this queue.
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| open E |
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| open Array<Any!> |
Returns an array containing all of the elements in this queue, in proper sequence.
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| open Array<T> |
Returns an array containing all of the elements in this queue, in proper sequence; the runtime type of the returned array is that of the specified array.
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| open String |
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| open Unit |
Transfers the element to a consumer, waiting if necessary to do so.
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| open Boolean |
Transfers the element to a waiting consumer immediately, if possible.
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| open Boolean |
Transfers the element to a consumer if it is possible to do so before the timeout elapses.
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| Inherited functions |
From class AbstractQueue
Boolean |
addAll(elements: Collection<E>)
Adds all of the elements in the specified collection to this queue. Attempts to addAll of a queue to itself result in IllegalArgumentException. Further, the behavior of this operation is undefined if the specified collection is modified while the operation is in progress.
This implementation iterates over the specified collection, and adds each element returned by the iterator to this queue, in turn. A runtime exception encountered while trying to add an element (including, in particular, a null element) may result in only some of the elements having been successfully added when the associated exception is thrown.
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Unit |
clear()
Removes all of the elements from this queue. The queue will be empty after this call returns.
This implementation repeatedly invokes poll until it returns null.
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E |
element()
Retrieves, but does not remove, the head of this queue. This method differs from peek only in that it throws an exception if this queue is empty.
This implementation returns the result of peek unless the queue is empty.
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E |
remove()
Retrieves and removes the head of this queue. This method differs from poll only in that it throws an exception if this queue is empty.
This implementation returns the result of poll unless the queue is empty.
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From class AbstractCollection
Boolean |
contains(element: E?)
Returns true if this collection contains the specified element. More formally, returns true if and only if this collection contains at least one element e such that (o==null ? e==null : o.equals(e)).
This implementation iterates over the elements in the collection, checking each element in turn for equality with the specified element.
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Boolean |
containsAll(elements: Collection<E>)
Returns true if this collection contains all of the elements in the specified collection.
This implementation iterates over the specified collection, checking each element returned by the iterator in turn to see if it's contained in this collection. If all elements are so contained true is returned, otherwise false.
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Boolean |
isEmpty()
Returns true if this collection contains no elements.
This implementation returns size() == 0.
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MutableIterator<E> |
iterator()
Returns an iterator over the elements contained in this collection.
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Boolean |
remove(element: E?)
Removes a single instance of the specified element from this collection, if it is present (optional operation). More formally, removes an element e such that (o==null ? e==null : o.equals(e)), if this collection contains one or more such elements. Returns true if this collection contained the specified element (or equivalently, if this collection changed as a result of the call).
This implementation iterates over the collection looking for the specified element. If it finds the element, it removes the element from the collection using the iterator's remove method.
Note that this implementation throws an UnsupportedOperationException if the iterator returned by this collection's iterator method does not implement the remove method and this collection contains the specified object.
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Boolean |
removeAll(elements: Collection<E>)
Removes all of this collection's elements that are also contained in the specified collection (optional operation). After this call returns, this collection will contain no elements in common with the specified collection.
This implementation iterates over this collection, checking each element returned by the iterator in turn to see if it's contained in the specified collection. If it's so contained, it's removed from this collection with the iterator's remove method.
Note that this implementation will throw an UnsupportedOperationException if the iterator returned by the iterator method does not implement the remove method and this collection contains one or more elements in common with the specified collection.
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Boolean |
retainAll(elements: Collection<E>)
Retains only the elements in this collection that are contained in the specified collection (optional operation). In other words, removes from this collection all of its elements that are not contained in the specified collection.
This implementation iterates over this collection, checking each element returned by the iterator in turn to see if it's contained in the specified collection. If it's not so contained, it's removed from this collection with the iterator's remove method.
Note that this implementation will throw an UnsupportedOperationException if the iterator returned by the iterator method does not implement the remove method and this collection contains one or more elements not present in the specified collection.
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Array<Any!> |
toArray()
Returns an array containing all of the elements in this collection. If this collection makes any guarantees as to what order its elements are returned by its iterator, this method must return the elements in the same order.
The returned array will be "safe" in that no references to it are maintained by this collection. (In other words, this method must allocate a new array even if this collection is backed by an array). The caller is thus free to modify the returned array.
This method acts as bridge between array-based and collection-based APIs.
This implementation returns an array containing all the elements returned by this collection's iterator, in the same order, stored in consecutive elements of the array, starting with index 0. The length of the returned array is equal to the number of elements returned by the iterator, even if the size of this collection changes during iteration, as might happen if the collection permits concurrent modification during iteration. The size method is called only as an optimization hint; the correct result is returned even if the iterator returns a different number of elements.
This method is equivalent to:
<code>List<E> list = new ArrayList<E>(size());
for (E e : this)
list.add(e);
return list.toArray();
</code>
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Array<T> |
toArray(a: Array<T>)
Returns an array containing all of the elements in this collection; the runtime type of the returned array is that of the specified array. If the collection 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 collection.
If this collection fits in the specified array with room to spare (i.e., the array has more elements than this collection), the element in the array immediately following the end of the collection is set to null. (This is useful in determining the length of this collection only if the caller knows that this collection does not contain any null elements.)
If this collection makes any guarantees as to what order its elements are returned by its iterator, this method must return the elements in the same order.
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 collection known to contain only strings. The following code can be used to dump the collection 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().
This implementation returns an array containing all the elements returned by this collection's iterator in the same order, stored in consecutive elements of the array, starting with index 0. If the number of elements returned by the iterator is too large to fit into the specified array, then the elements are returned in a newly allocated array with length equal to the number of elements returned by the iterator, even if the size of this collection changes during iteration, as might happen if the collection permits concurrent modification during iteration. The size method is called only as an optimization hint; the correct result is returned even if the iterator returns a different number of elements.
This method is equivalent to:
<code>List<E> list = new ArrayList<E>(size());
for (E e : this)
list.add(e);
return list.toArray(a);
</code>
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String |
toString()
Returns a string representation of this collection. The string representation consists of a list of the collection's elements in the order they are returned by its iterator, enclosed in square brackets ("[]"). Adjacent elements are separated by the characters ", " (comma and space). Elements are converted to strings as by String#valueOf(Object).
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From class Queue
Boolean |
offer(e: E)
Inserts the specified element into this queue if it is possible to do so immediately without violating capacity restrictions. When using a capacity-restricted queue, this method is generally preferable to add, which can fail to insert an element only by throwing an exception.
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E? |
peek()
Retrieves, but does not remove, the head of this queue, or returns null if this queue is empty.
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E? |
poll()
Retrieves and removes the head of this queue, or returns null if this queue is empty.
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| Properties |
| open Int |
Returns the number of elements in this queue.
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Public constructors
<init>
LinkedTransferQueue()
Creates an initially empty LinkedTransferQueue.
<init>
LinkedTransferQueue(c: MutableCollection<out E>!)
Creates a LinkedTransferQueue initially containing the elements of the given collection, added in traversal order of the collection's iterator.
| Parameters |
c |
MutableCollection<out E>!: the collection of elements to initially contain |
| Exceptions |
java.lang.NullPointerException |
if the specified collection or any of its elements are null |
Public methods
add
open fun add(element: E): Boolean
Inserts the specified element at the tail of this queue. As the queue is unbounded, this method will never throw IllegalStateException or return false.
| Parameters |
e |
the element to add |
| Exceptions |
java.lang.UnsupportedOperationException |
if the add operation is not supported by this collection |
java.lang.ClassCastException |
if the class of the specified element prevents it from being added to this queue |
java.lang.NullPointerException |
if the specified element is null |
java.lang.IllegalArgumentException |
if some property of the specified element prevents it from being added to this queue |
java.lang.IllegalStateException |
if the element cannot be added at this time due to capacity restrictions |
contains
open fun contains(element: E?): Boolean
Returns true if this queue contains the specified element. More formally, returns true if and only if this queue contains at least one element e such that o.equals(e).
| Parameters |
o |
object to be checked for containment in this queue |
| Return |
Boolean |
true if this queue contains the specified element |
| Exceptions |
java.lang.ClassCastException |
if the class of the specified element is incompatible with this queue (optional) |
java.lang.NullPointerException |
if the specified element is null (optional) |
drainTo
open fun drainTo(c: MutableCollection<in E>!): Int
| Return |
Int |
the number of elements transferred |
| Exceptions |
java.lang.UnsupportedOperationException |
if addition of elements is not supported by the specified collection |
java.lang.ClassCastException |
if the class of an element of this queue prevents it from being added to the specified collection |
java.lang.NullPointerException |
if the specified collection is null |
java.lang.IllegalArgumentException |
if the specified collection is this queue, or some property of an element of this queue prevents it from being added to the specified collection |
drainTo
open fun drainTo(
c: MutableCollection<in E>!,
maxElements: Int
): Int
| Parameters |
c |
MutableCollection<in E>!: the collection to transfer elements into |
maxElements |
Int: the maximum number of elements to transfer |
| Return |
Int |
the number of elements transferred |
| Exceptions |
java.lang.UnsupportedOperationException |
if addition of elements is not supported by the specified collection |
java.lang.ClassCastException |
if the class of an element of this queue prevents it from being added to the specified collection |
java.lang.NullPointerException |
if the specified collection is null |
java.lang.IllegalArgumentException |
if the specified collection is this queue, or some property of an element of this queue prevents it from being added to the specified collection |
getWaitingConsumerCount
open fun getWaitingConsumerCount(): Int
| Return |
Int |
the number of consumers waiting to receive elements |
hasWaitingConsumer
open fun hasWaitingConsumer(): Boolean
| Return |
Boolean |
true if there is at least one waiting consumer |
isEmpty
open fun isEmpty(): Boolean
Returns true if this queue contains no elements.
| Return |
Boolean |
true if this queue contains no elements |
iterator
open fun iterator(): MutableIterator<E>
Returns an iterator over the elements in this queue in proper sequence. The elements will be returned in order from first (head) to last (tail).
The returned iterator is weakly consistent.
| Return |
MutableIterator<E> |
an iterator over the elements in this queue in proper sequence |
offer
open fun offer(
e: E,
timeout: Long,
unit: TimeUnit!
): Boolean
Inserts the specified element at the tail of this queue. As the queue is unbounded, this method will never block or return false.
| Parameters |
e |
E: the element to add |
timeout |
Long: how long to wait before giving up, in units of unit |
unit |
TimeUnit!: a TimeUnit determining how to interpret the timeout parameter |
| Exceptions |
java.lang.InterruptedException |
if interrupted while waiting |
java.lang.ClassCastException |
if the class of the specified element prevents it from being added to this queue |
java.lang.NullPointerException |
if the specified element is null |
java.lang.IllegalArgumentException |
if some property of the specified element prevents it from being added to this queue |
offer
open fun offer(e: E): Boolean
Inserts the specified element at the tail of this queue. As the queue is unbounded, this method will never return false.
| Parameters |
e |
E: the element to add |
| Exceptions |
java.lang.ClassCastException |
if the class of the specified element prevents it from being added to this queue |
java.lang.NullPointerException |
if the specified element is null |
java.lang.IllegalArgumentException |
if some property of the specified element prevents it from being added to this queue |
peek
open fun peek(): E?
| Return |
E? |
the head of this queue, or null if this queue is empty |
poll
open fun poll(
timeout: Long,
unit: TimeUnit!
): E
| Parameters |
timeout |
Long: how long to wait before giving up, in units of unit |
unit |
TimeUnit!: a TimeUnit determining how to interpret the timeout parameter |
| Return |
E |
the head of this queue, or null if the specified waiting time elapses before an element is available |
| Exceptions |
java.lang.InterruptedException |
if interrupted while waiting |
poll
open fun poll(): E?
| Return |
E? |
the head of this queue, or null if this queue is empty |
put
open fun put(e: E): Unit
Inserts the specified element at the tail of this queue. As the queue is unbounded, this method will never block.
| Parameters |
e |
E: the element to add |
| Exceptions |
java.lang.InterruptedException |
if interrupted while waiting |
java.lang.ClassCastException |
if the class of the specified element prevents it from being added to this queue |
java.lang.NullPointerException |
if the specified element is null |
java.lang.IllegalArgumentException |
if some property of the specified element prevents it from being added to this queue |
remainingCapacity
open fun remainingCapacity(): Int
Always returns Integer.MAX_VALUE because a LinkedTransferQueue is not capacity constrained.
remove
open fun remove(element: E?): Boolean
Removes a single instance of the specified element from this queue, if it is present. More formally, removes an element e such that o.equals(e), if this queue contains one or more such elements. Returns true if this queue contained the specified element (or equivalently, if this queue changed as a result of the call).
| Parameters |
o |
element to be removed from this queue, if present |
| Return |
Boolean |
true if this queue changed as a result of the call |
| Exceptions |
java.lang.ClassCastException |
if the class of the specified element is incompatible with this queue (optional) |
java.lang.NullPointerException |
if the specified element is null (optional) |
java.lang.UnsupportedOperationException |
if the remove operation is not supported by this collection |
take
open fun take(): E
| Return |
E |
the head of this queue |
| Exceptions |
java.lang.InterruptedException |
if interrupted while waiting |
toArray
open fun toArray(): Array<Any!>
Returns an array containing all of the elements in this queue, in proper sequence.
The returned array will be "safe" in that no references to it are maintained by this queue. (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.
| Return |
Array<Any!> |
an array containing all of the elements in this queue |
toArray
open fun <T : Any!> toArray(a: Array<T>): Array<T>
Returns an array containing all of the elements in this queue, in proper sequence; the runtime type of the returned array is that of the specified array. 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.
Suppose x is a queue known to contain only strings. The following code can be used to dump the queue into a newly allocated array of String:
<code>String[] y = x.toArray(new String[0]);</code>
Note that
toArray(new Object[0]) is identical in function to
toArray().
| Parameters |
<T> |
the runtime type of the array to contain the collection |
a |
Array<T>: 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 |
| Return |
Array<T> |
an array containing all of the elements in this queue |
| Exceptions |
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 |
java.lang.NullPointerException |
if the specified array is null |
toString
open fun toString(): String
| Return |
String |
a string representation of the object. |
transfer
open fun transfer(e: E): Unit
Transfers the element to a consumer, waiting if necessary to do so.
More precisely, transfers the specified element immediately if there exists a consumer already waiting to receive it (in take or timed poll), else inserts the specified element at the tail of this queue and waits until the element is received by a consumer.
| Parameters |
e |
E: the element to transfer |
| Exceptions |
java.lang.InterruptedException |
if interrupted while waiting, in which case the element is not left enqueued |
java.lang.ClassCastException |
if the class of the specified element prevents it from being added to this queue |
java.lang.NullPointerException |
if the specified element is null |
java.lang.IllegalArgumentException |
if some property of the specified element prevents it from being added to this queue |
tryTransfer
open fun tryTransfer(e: E): Boolean
Transfers the element to a waiting consumer immediately, if possible.
More precisely, transfers the specified element immediately if there exists a consumer already waiting to receive it (in take or timed poll), otherwise returning false without enqueuing the element.
| Parameters |
e |
E: the element to transfer |
| Return |
Boolean |
true if the element was transferred, else false |
| Exceptions |
java.lang.ClassCastException |
if the class of the specified element prevents it from being added to this queue |
java.lang.NullPointerException |
if the specified element is null |
java.lang.IllegalArgumentException |
if some property of the specified element prevents it from being added to this queue |
tryTransfer
open fun tryTransfer(
e: E,
timeout: Long,
unit: TimeUnit!
): Boolean
Transfers the element to a consumer if it is possible to do so before the timeout elapses.
More precisely, transfers the specified element immediately if there exists a consumer already waiting to receive it (in take or timed poll), else inserts the specified element at the tail of this queue and waits until the element is received by a consumer, returning false if the specified wait time elapses before the element can be transferred.
| Parameters |
e |
E: the element to transfer |
timeout |
Long: how long to wait before giving up, in units of unit |
unit |
TimeUnit!: a TimeUnit determining how to interpret the timeout parameter |
| Return |
Boolean |
true if successful, or false if the specified waiting time elapses before completion, in which case the element is not left enqueued |
| Exceptions |
java.lang.InterruptedException |
if interrupted while waiting, in which case the element is not left enqueued |
java.lang.ClassCastException |
if the class of the specified element prevents it from being added to this queue |
java.lang.NullPointerException |
if the specified element is null |
java.lang.IllegalArgumentException |
if some property of the specified element prevents it from being added to this queue |
Properties
size
open val size: Int
Returns the number of elements in this queue. If this queue contains more than Integer.MAX_VALUE elements, 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 queues, determining the current number of elements requires an O(n) traversal.
| Return |
Int |
the number of elements in this queue |