[wip] initial commit

extracted useful snippets from other projects

src/de/pzzz/vertx/worker/QueuedWorker.java

@@ -0,0 +1,80 @@
+package de.pzzz.vertx.worker;
+
+import java.util.stream.Stream;
+
+import io.vertx.core.Future;
+
+public abstract class QueuedWorker<T,U> {
+	private QueueProcessingStatus<T> queue = new QueueProcessingStatus<>();
+	private int maxWorkers;
+
+	protected QueuedWorker(int maxWorkers) {
+		this.maxWorkers = maxWorkers;
+	}
+
+	public QueueProcessingStatus<T> startProcessing() {
+		getInputs().forEach(queue::enqueue);
+		startInputProcessing();
+		return queue;
+	}
+
+	public QueueProcessingStatus<T> continueProcessing() {
+		queue.setCalculate(true);
+		return queue;
+	}
+
+	public QueueProcessingStatus<T> stopProcessing() {
+		queue.setCalculate(false);
+		return queue;
+	}
+
+	public QueueProcessingStatus<T> processingStatus() {
+		return queue;
+	}
+
+	public QueueProcessingStatus<T> clearQueue() {
+		queue.clear();
+		return queue;
+	}
+
+	protected abstract Stream<T> getInputs();
+
+	protected abstract Future<U> doJob(final T job);
+
+	protected void beforeJob(final T job) {}
+
+	protected void afterSuccessfulJob(final T job, final U response) {}
+
+	protected void afterFailedJob(final T job, final Throwable error) {}
+
+	private void startInputProcessing() {
+		if (!queue.hasNext()) {
+			return;
+		}
+		T job = queue.startProcessing();
+		executeJob(job);
+		for (int i = 0; i < maxWorkers; i++) {
+			startNextJob();
+		}
+	}
+
+	private void startNextJob() {
+		if (!queue.isCalculate() || !queue.hasNext() || queue.getRunningCalculations() >= maxWorkers) {
+			return;
+		}
+		executeJob(queue.processNext());
+	}
+
+	private void executeJob(final T job) {
+		beforeJob(job);
+		doJob(job).onSuccess(response -> {
+			queue.complete();
+			afterSuccessfulJob(job, response);
+			startNextJob();
+		}).onFailure(error -> {
+			queue.complete();
+			afterFailedJob(job, error);
+			startNextJob();
+		});
+	}
+}