This happens because the actual proxy
object is an instance of a subclass of Cleaner. You are not proxying via an
interface, so HiveMind is generating a subclass to do the proxying.
From: Spencer
Crissman [mailto:[EMAIL PROTECTED]
Sent: Monday, November 07, 2005
8:54 AM
To: [email protected]
Subject: Multiple Instances of
Singleton Constructed?
I have a Tapestry application in which I am attempting
to use hivemind for some startup and shutdown handling. Basically
starting some services when loaded, and then cleaning up after them when the
application is undeployed or shutdown.
As a simple test, I have added the following to my hivemodule.xml:
<service-point id="Cleaner"
interface="Cleaner">
<invoke-factory
model="singleton">
<construct
class="Cleaner">
<event-listener service-id="hivemind.ShutdownCoordinator"/>
</construct>
</invoke-factory>
</service-point>
<contribution
configuration-id="hivemind.EagerLoad">
<load service-id="Cleaner"/>
</contribution>
And the following class to my project:
public class Cleaner implements RegistryShutdownListener {
public static int c;
public Cleaner( ) {
c = c + 1;
System.out.println("Cleaner
constructed! (" + String.valueOf(c) + ")");
}
public void registryDidShutdown() {
System.out.println("The
registry has shutdown! (" + String.valueOf(c) + ")" );
c = c - 1;
}
}
Oddly, when I go through the process of starting up and shutting down, I see
the following:
Cleaner constructed! (1)
Cleaner constructed! (2)
The registry has shutdown! (2)
The registry has shutdown! (1)
It appears that two instances of the Cleaner class are being constructed, when
what I really want is a singleton that gets created one time on startup, and
then gets called a single time at shutdown. From the messages it appears
that the problem is with the startup portion of the code, because if two
instances were not created, then there would be only one instance registered
for the shutdown event.
Where is hivemind being instructed to construct the second instance, and how
could I prevent it from happening?
Thanks in Advance,
Spencer
