LinkedBlockingQueue (Drools 4.0.0.11754MR2 API) - JBoss RULES 4.0.0.11754MR2 API 英文版文档

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org.drools.util.concurrent.locks
Class LinkedBlockingQueue

java.lang.Object
  java.util.AbstractCollection
      org.drools.util.concurrent.locks.AbstractCollection
          org.drools.util.concurrent.locks.AbstractQueue
              org.drools.util.concurrent.locks.LinkedBlockingQueue

All Implemented Interfaces:: Serializable, Iterable, Collection, BlockingQueue, Queue

public class LinkedBlockingQueue
extends AbstractQueue
implements BlockingQueue, Serializable
extends AbstractQueue
implements BlockingQueue, Serializable

An optionally-bounded blocking queue based on linked nodes. This queue orders elements FIFO (first-in-first-out). The head of the queue is that element that has been on the queue the longest time. The tail of the queue is that element that has been on the queue the shortest time. New elements are inserted at the tail of the queue, and the queue retrieval operations obtain elements at the head of the queue. Linked queues typically have higher throughput than array-based queues but less predictable performance in most concurrent applications.

The optional capacity bound constructor argument serves as a way to prevent excessive queue expansion. The capacity, if unspecified, is equal to Integer.MAX_VALUE. Linked nodes are dynamically created upon each insertion unless this would bring the queue above capacity.

This class and its iterator implement all of the optional methods of the Collection and Iterator interfaces.

This class is a member of the Java Collections Framework.

Since:: 1.5
Author:: Doug Lea
See Also:: Serialized Form

Constructor Summary

LinkedBlockingQueue()
          Creates a LinkedBlockingQueue with a capacity of Integer.MAX_VALUE.

LinkedBlockingQueue(Collection c)
          Creates a LinkedBlockingQueue with a capacity of Integer.MAX_VALUE, initially containing the elements of the given collection, added in traversal order of the collection's iterator.

LinkedBlockingQueue(int capacity)
          Creates a LinkedBlockingQueue with the given (fixed) capacity.

Method Summary

void clear()
          Atomically removes all of the elements from this queue.

int drainTo(Collection c)
          Removes all available elements from this queue and adds them to the given collection.

int drainTo(Collection c, int maxElements)
          Removes at most the given number of available elements from this queue and adds them to the given collection.

Iterator iterator()
          Returns an iterator over the elements in this queue in proper sequence.

boolean offer(Object e)
          Inserts the specified element at the tail of this queue if it is possible to do so immediately without exceeding the queue's capacity, returning true upon success and false if this queue is full.

boolean offer(Object e, long timeout, TimeUnit unit)
          Inserts the specified element at the tail of this queue, waiting if necessary up to the specified wait time for space to become available.

Object peek()
          Retrieves, but does not remove, the head of this queue, or returns null if this queue is empty.

Object poll()
          Retrieves and removes the head of this queue, or returns null if this queue is empty.

Object poll(long timeout, TimeUnit unit)
          Retrieves and removes the head of this queue, waiting up to the specified wait time if necessary for an element to become available.

void put(Object e)
          Inserts the specified element at the tail of this queue, waiting if necessary for space to become available.

int remainingCapacity()
          Returns the number of additional elements that this queue can ideally (in the absence of memory or resource constraints) accept without blocking.

boolean remove(Object o)
          Removes a single instance of the specified element from this queue, if it is present.

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

Object take()
          Retrieves and removes the head of this queue, waiting if necessary until an element becomes available.

Object[] toArray()
          Returns an array containing all of the elements in this queue, in proper sequence.

Object[] toArray(Object[] a)
          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.

String toString()


Methods inherited from class org.drools.util.concurrent.locks.AbstractQueue

add, addAll, element, remove

Methods inherited from class java.util.AbstractCollection

contains, containsAll, isEmpty, removeAll, retainAll

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.drools.util.concurrent.locks.BlockingQueue

add, contains

Methods inherited from interface org.drools.util.concurrent.locks.Queue

element, remove

Methods inherited from interface java.util.Collection

addAll, containsAll, equals, hashCode, isEmpty, removeAll, retainAll

Constructor Summary
`LinkedBlockingQueue()` Creates a `LinkedBlockingQueue` with a capacity of `Integer.MAX_VALUE`.
`LinkedBlockingQueue(Collection c)` Creates a `LinkedBlockingQueue` with a capacity of `Integer.MAX_VALUE`, initially containing the elements of the given collection, added in traversal order of the collection's iterator.
`LinkedBlockingQueue(int capacity)` Creates a `LinkedBlockingQueue` with the given (fixed) capacity.

Method Summary
`void`	`clear()` Atomically removes all of the elements from this queue.
`int`	`drainTo(Collection c)` Removes all available elements from this queue and adds them to the given collection.
`int`	`drainTo(Collection c, int maxElements)` Removes at most the given number of available elements from this queue and adds them to the given collection.
`Iterator`	`iterator()` Returns an iterator over the elements in this queue in proper sequence.
`boolean`	`offer(Object e)` Inserts the specified element at the tail of this queue if it is possible to do so immediately without exceeding the queue's capacity, returning `true` upon success and `false` if this queue is full.
`boolean`	`offer(Object e, long timeout, TimeUnit unit)` Inserts the specified element at the tail of this queue, waiting if necessary up to the specified wait time for space to become available.
`Object`	`peek()` Retrieves, but does not remove, the head of this queue, or returns `null` if this queue is empty.
`Object`	`poll()` Retrieves and removes the head of this queue, or returns `null` if this queue is empty.
`Object`	`poll(long timeout, TimeUnit unit)` Retrieves and removes the head of this queue, waiting up to the specified wait time if necessary for an element to become available.
`void`	`put(Object e)` Inserts the specified element at the tail of this queue, waiting if necessary for space to become available.
`int`	`remainingCapacity()` Returns the number of additional elements that this queue can ideally (in the absence of memory or resource constraints) accept without blocking.
`boolean`	`remove(Object o)` Removes a single instance of the specified element from this queue, if it is present.
`int`	`size()` Returns the number of elements in this queue.
`Object`	`take()` Retrieves and removes the head of this queue, waiting if necessary until an element becomes available.
`Object[]`	`toArray()` Returns an array containing all of the elements in this queue, in proper sequence.
`Object[]`	`toArray(Object[] a)` 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.
`String`	`toString()`

Methods inherited from class org.drools.util.concurrent.locks.AbstractQueue
`add, addAll, element, remove`

Methods inherited from class java.util.AbstractCollection
`contains, containsAll, isEmpty, removeAll, retainAll`

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait`

Methods inherited from interface org.drools.util.concurrent.locks.BlockingQueue
`add, contains`

Methods inherited from interface org.drools.util.concurrent.locks.Queue
`element, remove`

Methods inherited from interface java.util.Collection
`addAll, containsAll, equals, hashCode, isEmpty, removeAll, retainAll`

Constructor Detail

LinkedBlockingQueue

public LinkedBlockingQueue()

Creates a LinkedBlockingQueue with a capacity of Integer.MAX_VALUE.

LinkedBlockingQueue

public LinkedBlockingQueue(int capacity)

Creates a LinkedBlockingQueue with the given (fixed) capacity.

Parameters:: capacity - the capacity of this queue
Throws:: IllegalArgumentException - if capacity is not greater than zero

LinkedBlockingQueue

public LinkedBlockingQueue(Collection c)

Creates a LinkedBlockingQueue 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

Method Detail

size

public int size()

Returns the number of elements in this queue.

Specified by:: size in interface Collection
Specified by:: size in class AbstractCollection

Returns:: the number of elements in this queue

remainingCapacity

public int remainingCapacity()

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

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.

Specified by:: remainingCapacity in interface BlockingQueue

Returns:: the remaining capacity

put

public void put(Object e)
         throws InterruptedException

Inserts the specified element at the tail of this queue, waiting if necessary for space to become available.

Specified by:: put in interface BlockingQueue

Parameters:: e - the element to add
Throws:: InterruptedException - if interrupted while waiting; NullPointerException - if the specified element is null

offer

public boolean offer(Object e,
                     long timeout,
                     TimeUnit unit)
              throws InterruptedException

Inserts the specified element at the tail of this queue, waiting if necessary up to the specified wait time for space to become available.

Specified by:: offer in interface BlockingQueue

Parameters:: e - the element to add; timeout - how long to wait before giving up, in units of unit; unit - a TimeUnit determining how to interpret the timeout parameter
Returns:: true if successful, or false if the specified waiting time elapses before space is available.
Throws:: InterruptedException - if interrupted while waiting; NullPointerException - if the specified element is null

offer

public boolean offer(Object e)

Inserts the specified element at the tail of this queue if it is possible to do so immediately without exceeding the queue's capacity, returning true upon success and false if this queue is full. When using a capacity-restricted queue, this method is generally preferable to method add, which can fail to insert an element only by throwing an exception.

Specified by:: offer in interface BlockingQueue
Specified by:: offer in interface Queue

Parameters:: e - the element to add
Returns:: true if the element was added to this queue, else false
Throws:: NullPointerException - if the specified element is null

take

public Object take()
            throws InterruptedException

Description copied from interface: BlockingQueue

Retrieves and removes the head of this queue, waiting if necessary until an element becomes available.

Specified by:: take in interface BlockingQueue

Returns:: the head of this queue
Throws:: InterruptedException - if interrupted while waiting

poll

public Object poll(long timeout,
                   TimeUnit unit)
            throws InterruptedException

Description copied from interface: BlockingQueue

Retrieves and removes the head of this queue, waiting up to the specified wait time if necessary for an element to become available.

Specified by:: poll in interface BlockingQueue

Parameters:: timeout - how long to wait before giving up, in units of unit; unit - a TimeUnit determining how to interpret the timeout parameter
Returns:: the head of this queue, or null if the specified waiting time elapses before an element is available
Throws:: InterruptedException - if interrupted while waiting

poll

public Object poll()

Description copied from interface: Queue

Retrieves and removes the head of this queue, or returns null if this queue is empty.

Specified by:: poll in interface Queue

Returns:: the head of this queue, or null if this queue is empty

peek

public Object peek()

Description copied from interface: Queue

Retrieves, but does not remove, the head of this queue, or returns null if this queue is empty.

Specified by:: peek in interface Queue

Returns:: the head of this queue, or null if this queue is empty

remove

public boolean remove(Object o)

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).

Specified by:: remove in interface Collection
Specified by:: remove in interface BlockingQueue
Overrides:: remove in class AbstractCollection

Parameters:: o - element to be removed from this queue, if present
Returns:: true if this queue changed as a result of the call

toArray

public Object[] toArray()

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.

Specified by:: toArray in interface Collection
Overrides:: toArray in class AbstractCollection

Returns:: an array containing all of the elements in this queue

toArray

public Object[] toArray(Object[] a)

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:

     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
Overrides:: toArray in class AbstractCollection

Parameters:: 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
Returns:: an array containing all of the elements in this queue
Throws:: ArrayStoreException - if the runtime type of the specified array is not a supertype of the runtime type of every element in this queue; NullPointerException - if the specified array is null

toString

public String toString()

Overrides:: toString in class AbstractCollection

clear

public void clear()

Atomically removes all of the elements from this queue. The queue will be empty after this call returns.

Specified by:: clear in interface Collection
Overrides:: clear in class AbstractQueue

drainTo

public int drainTo(Collection c)

Description copied from interface: BlockingQueue

Removes all available elements from this queue and adds them to the given collection. This operation may be more efficient than repeatedly polling this queue. A failure encountered while attempting to add elements to collection c may result in elements being in neither, either or both collections when the associated exception is thrown. Attempts to drain 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.

Specified by:: drainTo in interface BlockingQueue

Parameters:: c - the collection to transfer elements into
Returns:: the number of elements transferred
Throws:: UnsupportedOperationException - if addition of elements is not supported by the specified collection; ClassCastException - if the class of an element of this queue prevents it from being added to the specified collection; NullPointerException - if the specified collection is null; 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

public int drainTo(Collection c,
                   int maxElements)

Description copied from interface: BlockingQueue

Removes at most the given number of available elements from this queue and adds them to the given collection. A failure encountered while attempting to add elements to collection c may result in elements being in neither, either or both collections when the associated exception is thrown. Attempts to drain 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.

Specified by:: drainTo in interface BlockingQueue

Parameters:: c - the collection to transfer elements into; maxElements - the maximum number of elements to transfer
Returns:: the number of elements transferred
Throws:: UnsupportedOperationException - if addition of elements is not supported by the specified collection; ClassCastException - if the class of an element of this queue prevents it from being added to the specified collection; NullPointerException - if the specified collection is null; 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

iterator

public Iterator iterator()

Returns an iterator over the elements in this queue in proper sequence. 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 Iterable
Specified by:: iterator in interface Collection
Specified by:: iterator in class AbstractCollection

Returns:: an iterator over the elements in this queue in proper sequence

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LinkedBlockingQueue (Drools 4.0.0.11754MR2 API) - JBoss RULES 4.0.0.11754MR2 API 英文版文档

org.drools.util.concurrent.locks Class LinkedBlockingQueue

LinkedBlockingQueue

LinkedBlockingQueue

LinkedBlockingQueue

size

remainingCapacity

put

offer

offer

take

poll

poll

peek

remove

toArray

toArray

toString

clear

drainTo

drainTo

iterator

org.drools.util.concurrent.locks
Class LinkedBlockingQueue