org.qbroker.common

Class ReservableCells

java.lang.Object

org.qbroker.common.ReservableCells

public class ReservableCells
extends java.lang.Object

ReservableCells are a fixed number of indexed cells that are reservable with the associated unigue IDs. All the reserved cells are always kept in their natural order.

A cell always is in one of the two different status, EMPTY, and RESERVED. All cells line up in a circular array. The cells in the same status always stay together in a group. Therefore the circle is divided into two segments of arcs. There are two marks separating those two arcs, ie, the two different groups of cells. Tail divieds empty cells and reserved cells. Head separates reserved cells and empty cells.

There are two methods to change the status of a cell. The method of reserve() is to reserve an empty cell and toggles its status from EMPTY to RESERVED. The method of cancel() is to cancel the reservation and swithes the cell from RESERVED to EMPTY.

capacity -- maximum number of cells in the list
size -- number of reserved cells
status -- status of a cell
id -- the fixed id of a cell

This is MT-Safe.

Author:

yannanlu@yahoo.com

Constructor Summary

Constructors

Constructor and Description
ReservableCells(java.lang.String name, int capacity) initialzes the list with capacity of cells

Method Summary

Modifier and Type	Method and Description
int	cancel(int id) cancels the reservation on the id-th cell and returns the size upon success or -1 otherwise.
void	clear() clear all cells and reset all marks
protected void	finalize()
int	getCapacity()
int	getCellStatus(int id) returns the status of the cell with the id if it is not out of bound or -1 otherwise
java.lang.String	getName()
int	queryIDs(int[] ids, int type) loads the ids of the type of cells in the natual order to the given array
int	reserve(long milliSec) reserves the next empty cell so that it is ready to be occupied
int	reserve(long milliSec, int id) reserves the id-th cell and returns the id upon success or -1 otherwise.
int	reserve(long milliSec, int begin, int len) reserves the first empty cell out of len cells starting from begin
int	size() returns the number of reserved cells

Methods inherited from class java.lang.Object

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

Constructor Detail

ReservableCells

public ReservableCells(java.lang.String name,
                       int capacity)

initialzes the list with capacity of cells

Method Detail

getName

public java.lang.String getName()

size

public int size()

returns the number of reserved cells

getCapacity

public int getCapacity()

getCellStatus

public int getCellStatus(int id)

returns the status of the cell with the id if it is not out of bound or -1 otherwise

cancel

public int cancel(int id)

cancels the reservation on the id-th cell and returns the size upon success or -1 otherwise.

reserve

public int reserve(long milliSec,
                   int id)

reserves the id-th cell and returns the id upon success or -1 otherwise. If milliSec is less than 0, there is no wait.

reserve

public int reserve(long milliSec,
                   int begin,
                   int len)

reserves the first empty cell out of len cells starting from begin

reserve

public int reserve(long milliSec)

reserves the next empty cell so that it is ready to be occupied

queryIDs

public int queryIDs(int[] ids,
                    int type)

loads the ids of the type of cells in the natual order to the given array

clear

public void clear()

clear all cells and reset all marks

finalize

protected void finalize()

Overrides:

finalize in class java.lang.Object