ostore.util
Class PriorityQueue

java.lang.Object
  |
  +--ostore.util.PriorityQueue

public class PriorityQueue

extends Object

PriorityQueue is a (blocking) priority queue. One of these will be used to store updates (and it will be read by the update thread) and the other stores query/success/fail messages for the location algorithm thread. Objects with small priorities come out first.

Version:

$Id: PriorityQueue.java,v 1.7 2003/04/24 23:38:56 strib Exp $

Author:

Westley Weimer

Field Summary

static boolean

DEBUG

Constructor Summary

PriorityQueue(int initial_capacity)
The constructor creates a new priority queue.

Method Summary

int	capacity() returns the current capacity of the heap.
boolean	check()
boolean	empty() returns the number of objects currently in the queue (0 means empty).
Object	extract(boolean blocking) extract() returns the object with the smallest priority in the queue and removes it from the queue.
boolean	insert(Object o, long prio, boolean blocking) inserts an object with the given priority.
int	maxSize() returns the maximum size of the heap.
void	print(int n)
void	printPrios()
boolean	remove(Object o) removes the given object from the priority queue. returns true if the object was found and removed, false otherwise.
boolean	removeAll(Object o) removes every instance the given object from the priority queue.
int	size() returns the number of objects currently in the queue (0 means empty).
Object	topObject(boolean blocking) topObject() returns the smallest priority object in the queue, or null if the queue is empty and blocking is not set.
long	topPriority(boolean blocking) topPriority() returns the smallest priority in the queue, or 0 if the queue is empty and blocking is not set.

Methods inherited from class java.lang.Object

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

Field Detail

DEBUG

public static final boolean DEBUG

See Also:

Constant Field Values

Constructor Detail

PriorityQueue

public PriorityQueue(int initial_capacity)

The constructor creates a new priority queue.

Parameters:

initial_capacity - the initial capacity of the heap.

Method Detail

size

public int size()

returns the number of objects currently in the queue (0 means empty).

empty

public boolean empty()

returns the number of objects currently in the queue (0 means empty).

maxSize

public int maxSize()

returns the maximum size of the heap.

capacity

public int capacity()

returns the current capacity of the heap.

insert

public boolean insert(Object o,
                      long prio,
                      boolean blocking)

inserts an object with the given priority. If the queue is full, the internal storage arrays are doubled in a very naive way.

Parameters:

blocking - ignored.

remove

public boolean remove(Object o)

removes the given object from the priority queue. returns true if the object was found and removed, false otherwise.

removeAll

public boolean removeAll(Object o)

removes every instance the given object from the priority queue. returns true if the object was found and removed, false otherwise.

topPriority

public long topPriority(boolean blocking)

topPriority() returns the smallest priority in the queue, or 0 if the queue is empty and blocking is not set.

topObject

public Object topObject(boolean blocking)

topObject() returns the smallest priority object in the queue, or null if the queue is empty and blocking is not set.

extract

public Object extract(boolean blocking)

extract() returns the object with the smallest priority in the queue and removes it from the queue. If the queue is empty and blocking is set, this operation blocks. If the queue is empty and blocking is not set, null is returned.

check

public boolean check()

print

public void print(int n)

printPrios

public void printPrios()