Package EDU.oswego.cs.dl.util.concurrent
Class BoundedPriorityQueue
- java.lang.Object
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- EDU.oswego.cs.dl.util.concurrent.SemaphoreControlledChannel
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- EDU.oswego.cs.dl.util.concurrent.BoundedPriorityQueue
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- All Implemented Interfaces:
BoundedChannel
,Channel
,Puttable
,Takable
public class BoundedPriorityQueue extends SemaphoreControlledChannel
A heap-based priority queue, using semaphores for concurrency control. The take operation returns the least element with respect to the given ordering. (If more than one element is tied for least value, one of them is arbitrarily chosen to be returned -- no guarantees are made for ordering across ties.) Ordering follows the JDK1.2 collection conventions: Either the elements must be Comparable, or a Comparator must be supplied. Comparison failures throw ClassCastExceptions during insertions and extractions. The implementation uses a standard array-based heap algorithm, as described in just about any data structures textbook.Put and take operations may throw ClassCastException if elements are not Comparable, or not comparable using the supplied comparator. Since not all elements are compared on each operation it is possible that an exception will not be thrown during insertion of non-comparable element, but will later be encountered during another insertion or extraction.
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Field Summary
Fields Modifier and Type Field Description protected Heap
heap_
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Fields inherited from class EDU.oswego.cs.dl.util.concurrent.SemaphoreControlledChannel
capacity_, putGuard_, takeGuard_
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Constructor Summary
Constructors Constructor Description BoundedPriorityQueue()
Create a priority queue with the current default capacity and relying on natural ordering.BoundedPriorityQueue(int capacity)
Create a priority queue with the given capacity, and relying on natural ordering.BoundedPriorityQueue(int capacity, java.util.Comparator cmp)
Create a priority queue with the given capacity and comparatorBoundedPriorityQueue(int capacity, java.util.Comparator cmp, java.lang.Class semaphoreClass)
Create a priority queue with the given capacity and comparator, using the supplied Semaphore class for semaphores.BoundedPriorityQueue(java.util.Comparator comparator)
Create a priority queue with the current default capacity and the given comparator
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description protected java.lang.Object
extract()
Internal mechanics of take.protected void
insert(java.lang.Object x)
Internal mechanics of put.java.lang.Object
peek()
Return, but do not remove object at head of Channel, or null if it is empty.
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Field Detail
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heap_
protected final Heap heap_
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Constructor Detail
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BoundedPriorityQueue
public BoundedPriorityQueue(int capacity, java.util.Comparator cmp) throws java.lang.IllegalArgumentException
Create a priority queue with the given capacity and comparator- Throws:
java.lang.IllegalArgumentException
- if capacity less or equal to zero
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BoundedPriorityQueue
public BoundedPriorityQueue(java.util.Comparator comparator)
Create a priority queue with the current default capacity and the given comparator
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BoundedPriorityQueue
public BoundedPriorityQueue(int capacity)
Create a priority queue with the given capacity, and relying on natural ordering.
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BoundedPriorityQueue
public BoundedPriorityQueue()
Create a priority queue with the current default capacity and relying on natural ordering.
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BoundedPriorityQueue
public BoundedPriorityQueue(int capacity, java.util.Comparator cmp, java.lang.Class semaphoreClass) throws java.lang.IllegalArgumentException, java.lang.NoSuchMethodException, java.lang.SecurityException, java.lang.InstantiationException, java.lang.IllegalAccessException, java.lang.reflect.InvocationTargetException
Create a priority queue with the given capacity and comparator, using the supplied Semaphore class for semaphores.- Throws:
java.lang.IllegalArgumentException
- if capacity less or equal to zerojava.lang.NoSuchMethodException
- If class does not have constructor that intializes permitsjava.lang.SecurityException
- if constructor information not accessiblejava.lang.InstantiationException
- if semaphore class is abstractjava.lang.IllegalAccessException
- if constructor cannot be calledjava.lang.reflect.InvocationTargetException
- if semaphore constructor throws an exception
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Method Detail
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insert
protected void insert(java.lang.Object x)
Description copied from class:SemaphoreControlledChannel
Internal mechanics of put.- Specified by:
insert
in classSemaphoreControlledChannel
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extract
protected java.lang.Object extract()
Description copied from class:SemaphoreControlledChannel
Internal mechanics of take.- Specified by:
extract
in classSemaphoreControlledChannel
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peek
public java.lang.Object peek()
Description copied from interface:Channel
Return, but do not remove object at head of Channel, or null if it is empty.
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