FairBlockingQueue (Apache Tomcat 7.0.67 API Documentation)

java.lang.Object
- org.apache.tomcat.jdbc.pool.FairBlockingQueue<E>

All Implemented Interfaces:

java.lang.Iterable<E>, java.util.Collection<E>, java.util.concurrent.BlockingQueue<E>, java.util.Queue<E>
```
public class FairBlockingQueue<E>
extends java.lang.Object
implements java.util.concurrent.BlockingQueue<E>
```
A simple implementation of a blocking queue with fairness waiting. invocations to method poll(...) will get handed out in the order they were received. Locking is fine grained, a shared lock is only used during the first level of contention, waiting is done in a lock per thread basis so that order is guaranteed once the thread goes into a suspended monitor state.
Not all of the methods of the BlockingQueue are implemented.

Author:

Filip Hanik

Nested Class Summary

Nested Classes
Modifier and Type	Class and Description
`protected class`	`FairBlockingQueue.ExchangeCountDownLatch<T>`
`protected class`	`FairBlockingQueue.FairIterator`
`protected class`	`FairBlockingQueue.ItemFuture<T>`

Constructor Summary

Constructors
Constructor and Description

FairBlockingQueue()
Creates a new fair blocking queue.

Constructors
Constructor and Description
`FairBlockingQueue()` Creates a new fair blocking queue.

Method Summary

Methods
Modifier and Type	Method and Description
`boolean`	`add(E e)`
`boolean`	`addAll(java.util.Collection<? extends E> c)`
`void`	`clear()`
`boolean`	`contains(java.lang.Object e)`
`boolean`	`containsAll(java.util.Collection<?> c)`
`int`	`drainTo(java.util.Collection<? super E> c)`
`int`	`drainTo(java.util.Collection<? super E> c, int maxElements)`
`E`	`element()`
`boolean`	`isEmpty()`
`java.util.Iterator<E>`	`iterator()`
`boolean`	`offer(E e)` Will always return true, queue is unbounded.
`boolean`	`offer(E e, long timeout, java.util.concurrent.TimeUnit unit)` Will never timeout, as it invokes the `offer(Object)` method.
`E`	`peek()`
`E`	`poll()`
`E`	`poll(long timeout, java.util.concurrent.TimeUnit unit)` Fair retrieval of an object in the queue.
`java.util.concurrent.Future<E>`	`pollAsync()` Request an item from the queue asynchronously
`void`	`put(E e)`
`int`	`remainingCapacity()`
`E`	`remove()`
`boolean`	`remove(java.lang.Object e)`
`boolean`	`removeAll(java.util.Collection<?> c)`
`boolean`	`retainAll(java.util.Collection<?> c)`
`int`	`size()`
`E`	`take()`
`java.lang.Object[]`	`toArray()`
`<T> T[]`	`toArray(T[] a)`

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

Methods inherited from interface java.util.Collection
equals, hashCode

- Constructor Detail
  - FairBlockingQueue
```
public FairBlockingQueue()
```
    Creates a new fair blocking queue.
- Method Detail
  - offer
```
public boolean offer(E e)
```
    Will always return true, queue is unbounded.
    
    Specified by:
    
    offer in interface java.util.concurrent.BlockingQueue<E>
    
    Specified by:
    
    offer in interface java.util.Queue<E>
  - offer
```
public boolean offer(E e,
            long timeout,
            java.util.concurrent.TimeUnit unit)
              throws java.lang.InterruptedException
```
    Will never timeout, as it invokes the offer(Object) method. Once a lock has been acquired, the
    
    Specified by:
    
    offer in interface java.util.concurrent.BlockingQueue<E>
    
    Throws:
    
    java.lang.InterruptedException
  - poll
```
public E poll(long timeout,
     java.util.concurrent.TimeUnit unit)
       throws java.lang.InterruptedException
```
    Fair retrieval of an object in the queue. Objects are returned in the order the threads requested them.
    
    Specified by:
    
    poll in interface java.util.concurrent.BlockingQueue<E>
    
    Throws:
    
    java.lang.InterruptedException
  - pollAsync
```
public java.util.concurrent.Future<E> pollAsync()
```
    Request an item from the queue asynchronously
    
    Returns:
    - a future pending the result from the queue poll request
  - remove
```
public boolean remove(java.lang.Object e)
```
    Specified by:
    
    remove in interface java.util.Collection<E>
    
    Specified by:
    
    remove in interface java.util.concurrent.BlockingQueue<E>
  - size
```
public int size()
```
    Specified by:
    
    size in interface java.util.Collection<E>
  - iterator
```
public java.util.Iterator<E> iterator()
```
    Specified by:
    
    iterator in interface java.lang.Iterable<E>
    
    Specified by:
    
    iterator in interface java.util.Collection<E>
  - poll
```
public E poll()
```
    Specified by:
    
    poll in interface java.util.Queue<E>
  - contains
```
public boolean contains(java.lang.Object e)
```
    Specified by:
    
    contains in interface java.util.Collection<E>
    
    Specified by:
    
    contains in interface java.util.concurrent.BlockingQueue<E>
  - add
```
public boolean add(E e)
```
    Specified by:
    
    add in interface java.util.Collection<E>
    
    Specified by:
    
    add in interface java.util.concurrent.BlockingQueue<E>
    
    Specified by:
    
    add in interface java.util.Queue<E>
  - drainTo
```
public int drainTo(java.util.Collection<? super E> c,
          int maxElements)
```
    Specified by:
    
    drainTo in interface java.util.concurrent.BlockingQueue<E>
    
    Throws:
    
    java.lang.UnsupportedOperationException - - this operation is not supported
  - drainTo
```
public int drainTo(java.util.Collection<? super E> c)
```
    Specified by:
    
    drainTo in interface java.util.concurrent.BlockingQueue<E>
    
    Throws:
    
    java.lang.UnsupportedOperationException - - this operation is not supported
  - put
```
public void put(E e)
         throws java.lang.InterruptedException
```
    Specified by:
    
    put in interface java.util.concurrent.BlockingQueue<E>
    
    Throws:
    
    java.lang.InterruptedException
  - remainingCapacity
```
public int remainingCapacity()
```
    Specified by:
    
    remainingCapacity in interface java.util.concurrent.BlockingQueue<E>
  - take
```
public E take()
       throws java.lang.InterruptedException
```
    Specified by:
    
    take in interface java.util.concurrent.BlockingQueue<E>
    
    Throws:
    
    java.lang.InterruptedException
  - addAll
```
public boolean addAll(java.util.Collection<? extends E> c)
```
    Specified by:
    
    addAll in interface java.util.Collection<E>
  - clear
```
public void clear()
```
    Specified by:
    
    clear in interface java.util.Collection<E>
    
    Throws:
    
    java.lang.UnsupportedOperationException - - this operation is not supported
  - containsAll
```
public boolean containsAll(java.util.Collection<?> c)
```
    Specified by:
    
    containsAll in interface java.util.Collection<E>
    
    Throws:
    
    java.lang.UnsupportedOperationException - - this operation is not supported
  - isEmpty
```
public boolean isEmpty()
```
    Specified by:
    
    isEmpty in interface java.util.Collection<E>
  - removeAll
```
public boolean removeAll(java.util.Collection<?> c)
```
    Specified by:
    
    removeAll in interface java.util.Collection<E>
    
    Throws:
    
    java.lang.UnsupportedOperationException - - this operation is not supported
  - retainAll
```
public boolean retainAll(java.util.Collection<?> c)
```
    Specified by:
    
    retainAll in interface java.util.Collection<E>
    
    Throws:
    
    java.lang.UnsupportedOperationException - - this operation is not supported
  - toArray
```
public java.lang.Object[] toArray()
```
    Specified by:
    
    toArray in interface java.util.Collection<E>
    
    Throws:
    
    java.lang.UnsupportedOperationException - - this operation is not supported
  - toArray
```
public <T> T[] toArray(T[] a)
```
    Specified by:
    
    toArray in interface java.util.Collection<E>
    
    Throws:
    
    java.lang.UnsupportedOperationException - - this operation is not supported
  - element
```
public E element()
```
    Specified by:
    
    element in interface java.util.Queue<E>
    
    Throws:
    
    java.lang.UnsupportedOperationException - - this operation is not supported
  - peek
```
public E peek()
```
    Specified by:
    
    peek in interface java.util.Queue<E>
    
    Throws:
    
    java.lang.UnsupportedOperationException - - this operation is not supported
  - remove
```
public E remove()
```
    Specified by:
    
    remove in interface java.util.Queue<E>
    
    Throws:
    
    java.lang.UnsupportedOperationException - - this operation is not supported

Class FairBlockingQueue<E>

Nested Class Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Methods inherited from interface java.util.Collection

Constructor Detail

FairBlockingQueue

Method Detail

offer

offer

poll

pollAsync

remove

size

iterator

poll

contains

add

drainTo

drainTo

put

remainingCapacity

take

addAll

clear

containsAll

isEmpty

removeAll

retainAll

toArray

toArray

element

peek

remove