org.umber.catalan.queues
Class SingleFileQueue

java.lang.Object
  org.umber.catalan.queues.SingleFileQueue

All Implemented Interfaces:

ICommandQueue

Direct Known Subclasses:

XmlFileQueue

public abstract class SingleFileQueue

extends java.lang.Object

implements ICommandQueue

Command queue which pulls commands from files on the file system.

Author:

jsheets

Constructor Summary

SingleFileQueue()

Method Summary

boolean	canQuit() Determines if the queue can safely shut down without losing its current status.
void	connect() Establishes a connection to the queue.
void	disconnect() Closes down the queue.
IForgeCommand	getNextCommand() Retrieves the next command in the queue, or null if queue is empty.
java.io.File	getQueueFile() Retrieves the current file that backs this queue.
boolean	isConnected() Determines if the queue is currently connected to a live command feed.
protected abstract IForgeCommand[]	parseQueueFile() Reads the contents of the file and converts it into an array of commands.
void	setQueueFile(java.io.File queueFile) Assigns a new queue file.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.umber.catalan.queues.ICommandQueue

sendResult

Constructor Detail

SingleFileQueue

public SingleFileQueue()

Method Detail

parseQueueFile

protected abstract IForgeCommand[] parseQueueFile()
                                           throws CatalanQueueException

Reads the contents of the file and converts it into an array of commands. That array becomes the entire contents of the queue.

Returns:

all commands in queue

Throws:

CatalanQueueException - if unable to load file

isConnected

public boolean isConnected()

Determines if the queue is currently connected to a live command feed.

Specified by:

isConnected in interface ICommandQueue

Returns:

true if connected

canQuit

public boolean canQuit()

Determines if the queue can safely shut down without losing its current status. This should only be called between commands.

This implementation returns true when the command is empty, but false whenver there are commands in the queue.

Specified by:

canQuit in interface ICommandQueue

Returns:

true if the queue can safely disconnect now

getQueueFile

public java.io.File getQueueFile()

Retrieves the current file that backs this queue.

Returns:

queue file

setQueueFile

public void setQueueFile(java.io.File queueFile)
                  throws CatalanQueueException

Assigns a new queue file. Can only be called when not connected.

Parameters:

queueFile - file containing queue commands

Throws:

CatalanQueueException - if currently connected

connect

public void connect()
             throws CatalanQueueException

Establishes a connection to the queue. Calls loadQueueFile().

Specified by:

connect in interface ICommandQueue

Throws:

CatalanQueueException - if unable to open queue file

disconnect

public void disconnect()
                throws CatalanQueueException

Closes down the queue. Should only call this if all commands have been retrieved.

Specified by:

disconnect in interface ICommandQueue

Throws:

CatalanQueueException - if queue is not empty

getNextCommand

public IForgeCommand getNextCommand()

Retrieves the next command in the queue, or null if queue is empty.

This implementation loads commands from a single queue file.

Specified by:

getNextCommand in interface ICommandQueue

Returns:

processing command