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Observer with RxJava/Quarkus

I started a Quarkus project, which (in part) shall watch for file changes on a text-file, read the added line(s) and then sends the added line(s) through a websocket connection to a client.
For watching the file changes and reading those I created the following class:
public class McServerService {
private String directory;
private List<String> currentLog;
private Observable<List<String>> observableLog;
private Thread logObserverThread;
public McServerService (String directory) {
this.currentLog = new ArrayList<String>();
this.observableLog = Observable.fromCallable(() -> this.currentLog);
this.directory = directory;
}
public void startWatching () {
this.logObserverThread = new Thread(new LogObserverThreadImpl(this.directory));
this.logObserverThread.start();
}
public void subscribeToLog (Observer<? super List<String>> observer) {
this.observableLog.subscribe(observer);
}
private class LogObserverThreadImpl implements Runnable {
BufferedReader br;
WatchService watchService;
private LogObserverThreadImpl (String directory) {
try {
this.br = new BufferedReader(new java.io.FileReader(directory + "\\" + "latest.log"));
String nextLine;
while ((nextLine = this.br.readLine()) != null) {
McServerService.this.currentLog.add(nextLine);
System.out.println(nextLine);
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
#Override
public void run() {
Path path = Paths.get(directory);
try {
System.out.println("entered try");
this.watchService = FileSystems.getDefault().newWatchService();
path.register(watchService, StandardWatchEventKinds.ENTRY_CREATE, StandardWatchEventKinds.ENTRY_MODIFY);
WatchKey key;
while ((key = this.watchService.take()) != null) {
for (WatchEvent<?> event : key.pollEvents()) {
if (event.context().toString().equals("latest.log")) {
String line = this.br.readLine();
McServerService.this.currentLog.add(line);
System.out.println(line);
}
}
key.reset();
}
System.out.println("after while");
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
Now the websocket would be handled by this class:
#ServerEndpoint("/test")
#ApplicationScoped
public class McServerWebSocket {
Map<String, Session> sessions = new ConcurrentHashMap<>();
McServerService mss = new McServerService("D:\\Spiele\\Minecraft");
#OnOpen
public void onOpen(Session session, #PathParam("name") String name) {
sessions.put(name, session);
}
#OnClose
public void onClose(Session session, #PathParam("name") String name) {
sessions.remove(name);
}
#OnError
public void onError(Session session, #PathParam("name") String name, Throwable throwable) {
sessions.remove(name);
}
#OnMessage
public void onMessage(String message, #PathParam("name") String name) {
Session c_session = sessions.get(name);
c_session.getAsyncRemote().sendObject("insert");
}
private class ConsoleLogObserverImpl implements Observer<List<String>>{
private ConsoleLogObserverImpl () {
}
#Override
public void onSubscribe(#NonNull Disposable d) {
// TODO Auto-generated method stub
System.out.println("subscribed");
}
#Override
public void onNext(#NonNull List<String> t) {
System.out.println(t.toString());
}
#Override
public void onError(#NonNull Throwable e) {
// TODO Auto-generated method stub
}
#Override
public void onComplete() {
// TODO Auto-generated method stub
System.out.println("finished");
}
}
}
I didnt implement the websocket yet, because my problem lies with observing the changes of
private List<String> currentLog; in the McServerServive class.
Unfortunately I deleted the main method in McServerWebSocket, that I used to test this, but that main method would essentially just create an instance of McServerWebSocket and then call the startWatching() method of its McServerService mss = new McServerService("D:\\Spiele\\Minecraft"); and its
public void subscribeToLog (Observer<? super List<String>> observer) {
this.observableLog.subscribe(observer);
}
method with the inner class:
private class ConsoleLogObserverImpl implements Observer<List<String>>
But the behaviour was not as I would have exspected. The output was:
subscribed
[]
finished
The observable was imediately terminating. Did I do something wrong when creating the Observable or did I completly misunderstand the usage RxJava?
How can I create an Observable class field and an Observer that triggers an action when the Observable is changed with RxJava/some Quarkus extension?

Thread got suspended after the put operation in SynchronousQueue

This is my code
import java.util.concurrent.SynchronousQueue;
public class Mywork {
public static void main(String args[])
{
SynchronousQueue<String> s=new SynchronousQueue<>();
Producer1 p1 =new Producer1(s);
Producer2 p2=new Producer2(s);
new Thread(p1).start();
new Thread(p2).start();
}
}
class Producer1 implements Runnable
{
SynchronousQueue<String> s=null;
Producer1(SynchronousQueue<String> q)
{
this.s=q;
}
#Override
public void run() {
// TODO Auto-generated method stub
try {
s.put("Suman");
System.out.println(s);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
//
class Producer2 implements Runnable
{
SynchronousQueue<String> s=null;
Producer2(SynchronousQueue<String> q)
{
this.s=q;
}
#Override
public void run() {
// TODO Auto-generated method stub
try {
s.put("Ghosh");
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
whenever the put is performed after that I am not ale to debug it , the control vanishes from the eclipse
any idea why it is happening ?

From the doc:
The put method will block until another thread retrieved data from SynchronousQueue.

put(E o)
Adds the specified element to this queue, waiting if necessary for
another thread to receive it.
That said, SynchronousQueue will not return until there is a corresponding take() call. And, you are adding element in both thread and caused wait.
So, changing
s.put("Ghosh");
to
String str = s.take();
will continue execution.

ZuulFallbackProvider not getting invoked

I am trying to have a fallback if Zuul does not find a service. I have the a ZuulSever with the below code:
#SpringBootApplication
#EnableZuulProxy
#EnableDiscoveryClient
public class ZuulServerApplication {
public static void main(String[] args) {
SpringApplication.run(ZuulServerApplication.class, args);
}
#Bean
public ZuulFallbackProvider fallBackProvider() {
return new ZuulFallbackProvider() {
#Override
public ClientHttpResponse fallbackResponse() {
return new ClientHttpResponse() {
#Override
public HttpHeaders getHeaders() {
return null;
}
#Override
public InputStream getBody() throws IOException {
return new ByteArrayInputStream("Hello".getBytes());
}
#Override
public String getStatusText() throws IOException {
// TODO Auto-generated method stub
return "Service Down";
}
#Override
public HttpStatus getStatusCode() throws IOException {
// TODO Auto-generated method stub
return HttpStatus.OK;
}
#Override
public int getRawStatusCode() throws IOException {
// TODO Auto-generated method stub
return 200;
}
#Override
public void close() {
// TODO Auto-generated method stub
}
};
}
#Override
public String getRoute() {
// TODO Auto-generated method stub
return "*";
}
};
}
}
When the service in my route is up and running, I am able to get the output. But when I bring down the service in the route, I expected the fallback to kick in. But I still see an error message instead of the fallback message. Why is the fallback not invoked? I am using Dalston Release version.

If you configure Zuul to directly connect to an URL for your route, it will use SimpleHostRoutingFilter, which will (almost) always return a 500 in case of an error. Any FallbackProviders will not kick in.
I used a custom SimpleHostRoutingFilter instead:
public class CustomErrorHostRoutingFilter extends SimpleHostRoutingFilter {
public CustomErrorHostRoutingFilter(ProxyRequestHelper helper, ZuulProperties properties, ApacheHttpClientConnectionManagerFactory connectionManagerFactory, ApacheHttpClientFactory httpClientFactory) {
super(helper, properties, connectionManagerFactory, httpClientFactory);
}
#Override
protected ZuulException handleException(Exception ex) {
if (ex instanceof ConnectTimeoutException) {
return new ZuulException(ex, "Downstream timeout", HttpServletResponse.SC_GATEWAY_TIMEOUT, ex.getMessage());
}
if (ex instanceof IOException) {
return new ZuulException(ex, "Downstream I/O error", HttpServletResponse.SC_SERVICE_UNAVAILABLE, ex.getMessage());
}
return super.handleException(ex);
}
}
Some kind of configuration class is required as well:
#Configuration
#EnableZuulProxy
public class ZuulConfiguration {
#Bean
public SimpleHostRoutingFilter simpleHostRoutingFilter(ProxyRequestHelper helper,
ZuulProperties zuulProperties,
ApacheHttpClientConnectionManagerFactory connectionManagerFactory,
ApacheHttpClientFactory httpClientFactory) {
return new CustomErrorHostRoutingFilter(helper, zuulProperties, connectionManagerFactory, httpClientFactory);
}
}

How to get a variable inside a Try-Catch block and inside asynchronous method

I want to know why the method myServer() return null, and not the value "result" that is assigned to finalResult inside " public void onSuccessInMainThread(...)" I'm new to java and there are some things I don't understand
protected LemmaValidationJob finalResult;
public LemmaValidationJob myServer(){
TaskConfiguration config = new TaskConfiguration(TaskType.RELATION);
config.setLanguage(Language.EN);
try{
AnnotationManager.getInstance().getData(config,
new MainThreadCallback<LemmaValidationJob>(){
#Override
public void onSuccessInMainThread(LemmaValidationJob result){
finalResult = result;
}
#Override
public void onFailureInMainThread(Throwable cause){
// TODO Auto-generated method stub
}
});
} catch (AuthenticationRequiredException e) {
System.err.println("NO LOGIN");
e.printStackTrace();
}
return finalResult;
}

The problem is that your myServer() method probably returns before the execution of the onSuccessInMainThread() method.
If a method performs an ansychronous thread then in most cases the calling method must also have an asynchronous signature. So in this case myServer must be void, and must receive a callback as a parameter. So it will be something like
public void myServer(Consumer<LemmaValidationJob> onSuccess){
TaskConfiguration config = new TaskConfiguration(TaskType.RELATION);
config.setLanguage(Language.EN);
try{
AnnotationManager.getInstance().getData(config,
new MainThreadCallback<LemmaValidationJob>(){
#Override
public void onSuccessInMainThread(LemmaValidationJob result){
onSuccess.apply(result);
}
#Override
public void onFailureInMainThread(Throwable cause){
// TODO Auto-generated method stub
}
});
} catch (AuthenticationRequiredException e) {
System.err.println("NO LOGIN");
e.printStackTrace();
}
}

using threads with spring boot

i'm using spring boot, i have some class services and controleurs, now i want to create a thread that verify if a folder contain files or not? i create the class for verifing the existance of files but now i want to integrate this class with spring boot. this is my code :
public class Linstenerfile implements Runnable{
String fichier ="C:/Project/containerFiles/snapshot.txt";
ControlleurFile l =new ControlleurFile();
File file = new File(fichier);
#Override
public void run() {
// TODO Auto-generated method stub
while(true)
{
if(file.exists())
{
try {
File Subscriberoffref=l.CreateSubscripberFile(file,"data");
List<AbonneOffreDTO1> suscriberOffredata=l.GetCvsData(Subscriberoffref);
l.VerifyData(suscriberOffredata);
// file.delete();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
else
{
System.out.println("thread running");
}
}
}
}
and this the springboot class application:
#SpringBootApplication
public class GateWayProjectApplication {
public static void main(String[] args) {
SpringApplication.run(GateWayProjectApplication.class, args);
Linstenerfile k =new Linstenerfile();
k.run();
}
and this is the code verifydata method
public void VerifyData(List<AbonneOffreDTO1> lisaboff)
{
System.out.println(abonneservice.GetAbonnesize());
}