Like the idea (and we can extend it to Generators, Serializers, etc.), but:
Instinctively dislike the hack in the component selector.
/LS
On Wed, 22 Sep 2004 10:31:01 -0400, Vadim Gritsenko
<[EMAIL PROTECTED]> wrote:
> Y'all,
>
> Some time ago I remember discussions about making transformers
> threadsafe, major changes, about Cocoon 3, etc. Yesterday it occured to
> me that Transformers can easily be made ThreadSafe with only additions
> to current Cocoon architecture without any major rewrites. It can be
> done in this way:
>
> Add new interface marking threadsafe transformer:
> public interface TransformerFactory {
> Transformer getTransformer();
> }
>
> Override select method in ComponentSelector:
> public Component select(Object hint) throws ComponentException {
> Component component = super.select(hint);
> if (this.roleId == TRANSFORMER) {
> if (component instanceof TransformerFactory) {
> return ((TransformerFactory)component).getTransformer();
> }
> }
>
> return component;
> }
> (it is in org.apache.cocoon.components.treeprocessor.sitemap package)
>
> Modify existing transformer so that transformer class implements
> TransformerFactory, ThreadSafe, and nested class TransformerImpl
> implements Transformer, CacheableProcessingComponent (and it can extend
> AbstractXMLPipe). On the example of EncodeURLTransformer:
> public class EncodeURLTransformer
> implements TransformerFactory, Configurable, ThreadSafe {
>
> public void configure(Configuration config) {...}
>
> public Transformer getTransformer() {
> return new TransformerImpl();
> }
>
> private class TransformerImpl
> extends AbstractTransformer
> implements CacheableProcessingComponent {
>
> public void setup(SourceResolver resolver,
> Map objectModel,
> String source,
> Parameters parameters) {...}
>
> public Serializable getKey() {...}
>
> public SourceValidity getValidity() {...}
>
> public void startElement(String uri,
> String name,
> String raw,
> Attributes attributes) {...}
> ...
> }
> }
>
> Thus ThreadSafe transformer is a factory creating instances of SAX pipes
> performing actual transformation. Pluses of this approach, as I see it, are:
> * Transformer is <init>ed / contextualize()d / service()ed /
> configure()d / etc just once. Saves CPU cycles.
> * Transformer global configuration / context / components
> stored in single instance of ThreadSafe transformer instead
> of beeing copied in each instance of usual pooled
> transformer. Saves memory.
> * Users of ComponentSelector still receive instance of
> Transformer as they used to expect. Backward compatibility.
>
> Now question; is it a good idea to check in this code into 2.2? Any
> drawbacks of this approach?
>
> Thanks,
> Vadim
>
>
