package net.jcip.examples;
import java.util.*;
import java.util.concurrent.*;
import static net.jcip.examples.LaunderThrowable.launderThrowable;
/**
* Renderer
*
* Using CompletionService to render page elements as they become available
*
* @author Brian Goetz and Tim Peierls
*/
public abstract class Renderer {
private final ExecutorService executor;
Renderer(ExecutorService executor) {
this.executor = executor;
}
void renderPage(CharSequence source) {
final List info = scanForImageInfo(source);
CompletionService completionService =
new ExecutorCompletionService(executor);
for (final ImageInfo imageInfo : info)
completionService.submit(new Callable() {
public ImageData call() {
return imageInfo.downloadImage();
}
});
renderText(source);
try {
for (int t = 0, n = info.size(); t < n; t++) {
Future f = completionService.take();
ImageData imageData = f.get();
renderImage(imageData);
}
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
} catch (ExecutionException e) {
throw launderThrowable(e.getCause());
}
}
interface ImageData {
}
interface ImageInfo {
ImageData downloadImage();
}
abstract void renderText(CharSequence s);
abstract List scanForImageInfo(CharSequence s);
abstract void renderImage(ImageData i);
}