[jbossseam-issues] [JBoss JIRA] Updated: (JBSEAM-3621) Support hot-deployment of instrumented wicket components

Clint Popetz (JIRA) jira-events at lists.jboss.org
Tue Nov 4 13:32:20 EST 2008

     [ https://jira.jboss.org/jira/browse/JBSEAM-3621?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Clint Popetz updated JBSEAM-3621:

    Attachment: seam-wicket-hotel-example-hotdeploy.patch

Here's a patch that modifies the wicket hotel example to instrument the wicket components at build time if the instrumentAtBuildTime property is set, which it is by default.  If debug=true, the resulting classes are hot deployed to dev.  If not, they're put in WEB-INF/classes. 

Note that the existing build compiled the wicket classes directly to WEB-INF/wicket.  I've changed this to build them to build-web/, instrument them to instrumented-web, and then copy from either to the correct location in the exploded archive.  Also, I keep a cache file around to only instrument files that are changed, as instrumentation isn't cheap.

I was able to modify wicket classes on the fly with this change.

> Support hot-deployment of instrumented wicket components
> --------------------------------------------------------
>                 Key: JBSEAM-3621
>                 URL: https://jira.jboss.org/jira/browse/JBSEAM-3621
>             Project: Seam
>          Issue Type: Patch
>            Reporter: Clint Popetz
>            Assignee: Pete Muir
>             Fix For: 2.1.1.CR1
>         Attachments: seam-hot-deploy-wicket.diff, seam-hot-deploy-wicket2.diff, seam-wicket-hotel-example-hotdeploy.patch, WicketFilter.java.patch
> Attached is a patch to add support for hot deployment of wicket components that have been instrumented by the wicket instrumentation ant task from JBSEAM-3505.  That patch should be applied first to avoid conflicts.
> The elements of this patch are:
> * I need access to the HotDeploymentStrategy  from the wicket classloader, but it's currently only exposed in the event context for the duration of startup.  I've changed this to place it in the application context.  I don't know if that's correct, but it seemed like a reasonable place to store it.  So HotDeploymentStrategy now does this in its constructor.
> * Initialization.redeploy now calls ServletLifecycle.beginReinitialization before createHotDeployment so that the app context exists.  This puts createHotDeployment in the same contextual surroundings as its other invocation in Initialization.init().
> * The WicketFilter needs to be re-initialized upon redeployment.  So WicketFilter now delays initialization of the delegate (the @Unwrapped anonymous subclass of wicket's own WicketFilter) until the first actual request, and at each request it checks a stored initTime against Init.getTimestamp().  If they've changed, it re-inits.  Also, I place WicketFilter within the HotDeployFilter via @Filter(within), so that all of this can work.  This survives the absence of the HotDeployFilter, i.e. if you deploy without jboss-seam-debug.jar, SeamFilter ignores the missing within reference, and the WicketClassLoader just uses the thread's contextClassLoader for the parent of the instrumenting class loader.
> * WicketClassLoader uses the HotDeploymentStrategy's classloader as the parent classloader, if it exists.  This means that runtime-instrumented wicket components can reference hot-deployed wicket components, but not vice-versa, similar to how hot-deployable seam components can reference normally deployed components, but not vice-versa.

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