to.etc.domui.server.reloader

Class Reloader

java.lang.Object

to.etc.domui.server.reloader.Reloader

public final class Reloader
extends Object

This class handles loading classes in such a way that when their source .class files change we discard existing info and cause the classes to be reloaded. Used in development.

Application class chores

The DomApplication class is responsible for instantiating all user-changeable classes by converting strings to Class instances. This DomApplication class itself is not reloadable (for now), but it's classloader must pass all loads to the classloader here so we can determine if a class is to be reloadable.

We have a total of three ClassLoaders in this process:

• The ReloadingClassLoader is a discardable ClassLoader. All classes loaded thru this class are ALWAYS watched for changes. The system can ask this ClassLoader to check if any of the classes it loaded have changed. When the system decides to reload the classes it discards the current instance of the ReloadingClassLoader, thereby invalidating all of the classes loaded by it. These classes will become garbage as soon as all references to it are gone. The ReloadingClassLoader (for now) never contains the Application class, but the Application class will force loads of classes it instantiates thru the ReloadingClassLoader.
• The CheckingClassLoader is the ClassLoader used to load the Application class, and only that class. It causes all classes that are loaded via the Application class to pass through it, and it decides how to load those classes: either through the normal classloader (WebappLoader, usually) or thru the ReloadingClassLoader.

Author:

Frits Jalvingh Created on May 22, 2008

Constructor Summary

Constructors

Constructor and Description
Reloader(String paths, String pathsWatchOnly) Create a reloader which handles the specified classes.

Method Summary

Modifier and Type	Method and Description
void	clear()
ClassLoader	getReloadingLoader()
URL[]	getUrls()
boolean	isChanged() Checks for changes on this classloader.
Class<DomApplication>	loadApplication(String classname) Used to load the Application class so it uses the proper ClassLoader.

Methods inherited from class java.lang.Object

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

Constructor Detail

Reloader

public Reloader(String paths,
                String pathsWatchOnly)

Create a reloader which handles the specified classes.

Parameters:

paths -

patternsWatchOnly, - these patterns will be only watched not really reloaded. It makes sure the reloader kicks in. Bundles and MetaData will be reloaded.

Method Detail

getUrls

public URL[] getUrls()

getReloadingLoader

public ClassLoader getReloadingLoader()

loadApplication

public Class<DomApplication> loadApplication(String classname)
                                      throws Exception

Used to load the Application class so it uses the proper ClassLoader.

Parameters:

classname -

Returns:

Throws:

Exception

isChanged

public boolean isChanged()

Checks for changes on this classloader. This blocks if another thread is checking and if so it does not sweep again when that thread completes the sweep.

clear

public void clear()