AsyncAgentResource.java
/*
* Copyright (c) 2014, 2018 Oracle and/or its affiliates. All rights reserved.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Distribution License v. 1.0, which is available at
* http://www.eclipse.org/org/documents/edl-v10.php.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
package org.glassfish.jersey.examples.rx.agent;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Queue;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Future;
import java.util.concurrent.ScheduledThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.util.stream.Collectors;
import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.client.InvocationCallback;
import javax.ws.rs.client.WebTarget;
import javax.ws.rs.container.AsyncResponse;
import javax.ws.rs.container.Suspended;
import org.glassfish.jersey.examples.rx.domain.AgentResponse;
import org.glassfish.jersey.examples.rx.domain.Calculation;
import org.glassfish.jersey.examples.rx.domain.Destination;
import org.glassfish.jersey.examples.rx.domain.Forecast;
import org.glassfish.jersey.examples.rx.domain.Recommendation;
import org.glassfish.jersey.internal.guava.ThreadFactoryBuilder;
import org.glassfish.jersey.process.JerseyProcessingUncaughtExceptionHandler;
import org.glassfish.jersey.server.ManagedAsync;
import org.glassfish.jersey.server.Uri;
/**
* Obtain information about visited (destination) and recommended (destination, forecast, price) places for "Async" user. Uses
* standard JAX-RS async approach to obtain the data.
*
* @author Michal Gajdos
*/
@Path("agent/async")
@Produces("application/json")
public class AsyncAgentResource {
@Uri("remote/destination")
private WebTarget destination;
@Uri("remote/calculation/from/{from}/to/{to}")
private WebTarget calculation;
@Uri("remote/forecast/{destination}")
private WebTarget forecast;
private final ExecutorService executor;
public AsyncAgentResource() {
executor = new ScheduledThreadPoolExecutor(20, new ThreadFactoryBuilder()
.setNameFormat("jersey-rx-client-async-%d")
.setUncaughtExceptionHandler(new JerseyProcessingUncaughtExceptionHandler())
.build());
}
@GET
@ManagedAsync
public void async(@Suspended final AsyncResponse async) {
final long time = System.nanoTime();
final AgentResponse response = new AgentResponse();
final CountDownLatch outerLatch = new CountDownLatch(2);
final Queue<String> errors = new ConcurrentLinkedQueue<>();
// Obtain visited destinations.
destination.path("visited").request()
// Identify the user.
.header("Rx-User", "Async")
// Async invoker.
.async()
// Return a list of destinations
.get(new InvocationCallback<List<Destination>>() {
@Override
public void completed(final List<Destination> destinations) {
response.setVisited(destinations);
outerLatch.countDown();
}
@Override
public void failed(final Throwable throwable) {
errors.offer("Visited: " + throwable.getMessage());
outerLatch.countDown();
}
});
// Obtain recommended destinations. (does not depend on visited ones)
destination.path("recommended").request()
// Identify the user.
.header("Rx-User", "Async")
// Async invoker.
.async()
// Return a list of destinations.
.get(new InvocationCallback<List<Destination>>() {
@Override
public void completed(final List<Destination> recommended) {
final CountDownLatch innerLatch = new CountDownLatch(recommended.size() * 2);
// Forecasts. (depend on recommended destinations)
final Map<String, Forecast> forecasts = Collections.synchronizedMap(new HashMap<>());
for (final Destination dest : recommended) {
forecast.resolveTemplate("destination", dest.getDestination()).request()
.async()
.get(new InvocationCallback<Forecast>() {
@Override
public void completed(final Forecast forecast) {
forecasts.put(dest.getDestination(), forecast);
innerLatch.countDown();
}
@Override
public void failed(final Throwable throwable) {
errors.offer("Forecast: " + throwable.getMessage());
innerLatch.countDown();
}
});
}
// Calculations. (depend on recommended destinations)
final List<Future<Calculation>> futures = recommended.stream()
.map(dest -> calculation.resolveTemplate("from", "Moon").resolveTemplate("to",
dest.getDestination()).request().async().get(Calculation.class))
.collect(Collectors.toList());
final Map<String, Calculation> calculations = new HashMap<>();
while (!futures.isEmpty()) {
final Iterator<Future<Calculation>> iterator = futures.iterator();
while (iterator.hasNext()) {
final Future<Calculation> f = iterator.next();
if (f.isDone()) {
try {
final Calculation calculation = f.get();
calculations.put(calculation.getTo(), calculation);
innerLatch.countDown();
} catch (final Throwable t) {
errors.offer("Calculation: " + t.getMessage());
innerLatch.countDown();
} finally {
iterator.remove();
}
}
}
}
// Have to wait here for dependent requests ...
try {
if (!innerLatch.await(10, TimeUnit.SECONDS)) {
errors.offer("Inner: Waiting for requests to complete has timed out.");
}
} catch (final InterruptedException e) {
errors.offer("Inner: Waiting for requests to complete has been interrupted.");
}
// Recommendations.
final List<Recommendation> recommendations = new ArrayList<>(recommended.size());
for (final Destination dest : recommended) {
final Forecast fore = forecasts.get(dest.getDestination());
final Calculation calc = calculations.get(dest.getDestination());
recommendations.add(new Recommendation(dest.getDestination(),
fore != null ? fore.getForecast() : "N/A", calc != null ? calc.getPrice() : -1));
}
response.setRecommended(recommendations);
outerLatch.countDown();
}
@Override
public void failed(final Throwable throwable) {
errors.offer("Recommended: " + throwable.getMessage());
outerLatch.countDown();
}
});
// ... and have to wait also here for independent requests.
try {
if (!outerLatch.await(10, TimeUnit.SECONDS)) {
errors.offer("Outer: Waiting for requests to complete has timed out.");
}
} catch (final InterruptedException e) {
errors.offer("Outer: Waiting for requests to complete has been interrupted.");
}
// Do something with errors.
// ...
response.setProcessingTime((System.nanoTime() - time) / 1000000);
async.resume(response);
}
}