Package noaa.coastwatch.io.tile

Class TileDeliveryOperation

java.lang.Object

java.util.Observable

noaa.coastwatch.io.tile.TileDeliveryOperation

public class TileDeliveryOperation
extends Observable

A TileDeliveryOperation represents an asynchronous process for delivering tiles of data from a TileSource to a number of Observer objects. Each observer receives a TilingScheme.Tile object after each tile has been read from the source. If an exception is encountered while delivering tiles, the observer object will be null, and the getLastReadException() method will return the latest exception received.

Since:

3.3.1

Author:

Peter Hollemans

Constructor Summary

Constructors

Constructor	Description
TileDeliveryOperation(TileSource source, Iterable<TilingScheme.TilePosition> positions)	Creates a new delivery operation that reads tiles from a source.

Method Summary

Modifier and Type	Method	Description
void	cancel()	Cancels this operation.
IOException	getLastReadException()	Gets the last exception received from reading tiles from the source.
TileSource	getSource()	Gets the source for this delivery operation.
boolean	isFinished()	Checks if this operation is finished.
static void	main(String[] argv)	Tests this class.
void	start()	Starts the operation.
void	waitUntilFinished()	Waits for the operation to finish.

Methods inherited from class java.util.Observable

addObserver, clearChanged, countObservers, deleteObserver, deleteObservers, hasChanged, notifyObservers, notifyObservers, setChanged

Methods inherited from class java.lang.Object

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

Constructor Details

TileDeliveryOperation

public TileDeliveryOperation(TileSource source,
 Iterable<TilingScheme.TilePosition> positions)

Creates a new delivery operation that reads tiles from a source. The operation is created but not started.

Parameters:

source - the source to read tile data from.

positions - the positions to read.

See Also:

• start()

Method Details

getSource

public TileSource getSource()

Gets the source for this delivery operation.

Returns:

the tile source.

getLastReadException

public IOException getLastReadException()

Gets the last exception received from reading tiles from the source.

Returns:

the last exception, or null if no exception has occurred.

start

public void start()

Starts the operation. Tiles will begin to be read in a parallel thread, and observers notified when tiles are ready. This method returns immediately, and may only be called once.

See Also:

• waitUntilFinished()
• cancel()
• isFinished

waitUntilFinished

public void waitUntilFinished()
                       throws InterruptedException

Waits for the operation to finish. This method should only be called to synchronize the operation, and will exit when the delivery operation is complete. If no operation is in progress, the method exits immediately.

Throws:

InterruptedException - if the current thread is interrupted waiting for the operation to finish.

cancel

public void cancel()

Cancels this operation. This method may only be called if the start() method has been called.

isFinished

public boolean isFinished()

Checks if this operation is finished.

Returns:

the finished flag, true if finished (either because the operation was cancelled, or ran out of tiles to deliver), or false if running or not started yet.

See Also:

• cancel()
• start()

main

public static void main(String[] argv)
                 throws Exception

Tests this class.

Parameters:

argv - the array of command line parameters.

Throws:

Exception