package jcip;

import java.util.List;

import java.util.concurrent.*;

import static jcip.LaunderThrowable.launderThrowable;

/**

* ExecutorCompletionService implements CompletionService

* QueueingFuture<V> extends FutureTask<V>

*

* @author zqw

* @date 2021/4/7

*/

abstract class AbstractRenderer {

private final ExecutorService executor;

AbstractRenderer(ExecutorService executor) {

this.executor = executor;

}

void renderPage(CharSequence source) {

final List<ImageInfo> info = scanForImageInfo(source);

CompletionService<ImageData> completionService =

new ExecutorCompletionService<>(executor);

for (final ImageInfo imageInfo : info) {

completionService.submit(imageInfo::downloadImage);

}

renderText(source);

try {

for (int t = 0, n = info.size(); t < n; t++) {

Future<ImageData> 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 {

/**

* downloadImage

* @return ImageData

*/

ImageData downloadImage();

}

/**

* renderText

* @param s CharSequence

*/

abstract void renderText(CharSequence s);

/**

* scanForImageInfo

* @param s CharSequence

* @return List<ImageInfo>

*/

abstract List<ImageInfo> scanForImageInfo(CharSequence s);

/**

* renderImage

* @param i ImageData

*/

abstract void renderImage(ImageData i);

}