fix: Initial state fix - fetch data and block executions until completed

src/main/java/eu/ztsh/lfr/Main.java

@@ -5,11 +5,13 @@ import org.springframework.boot.autoconfigure.SpringBootApplication;
 import org.springframework.boot.context.properties.ConfigurationPropertiesScan;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.scheduling.annotation.EnableAsync;
+import org.springframework.scheduling.annotation.EnableScheduling;
 
 @SpringBootApplication
 @EnableConfigurationProperties
 @ConfigurationPropertiesScan
 @EnableAsync
+@EnableScheduling
 public class Main {
 
     public static void main(String[] args) {

src/main/java/eu/ztsh/lfr/core/impl/TemperaturesServiceImpl.java

@@ -18,13 +18,23 @@ public class TemperaturesServiceImpl implements TemperaturesService {
     @Nonnull
     @Override
     public List<Average> getTemperaturesFor(String city) {
-        throw new UnsupportedOperationException("Not supported yet.");
+        synchronized (this) {
+            while (averages == null) {
+                try {
+                    wait();
+                } catch (InterruptedException e) {
+                    throw new IllegalStateException(e);
+                }
+            }
+            return averages.get(city);
+        }
     }
 
     @EventListener(FileProcessedEvent.class)
     public void updateTemperatures(FileProcessedEvent event) {
         synchronized (this) {
             averages = event.averages();
+            notifyAll();
         }
     }
 

src/main/java/eu/ztsh/lfr/core/impl/files/FileLoadingService.java

@@ -1,6 +1,7 @@
 package eu.ztsh.lfr.core.impl.files;
 
 import eu.ztsh.lfr.config.DataProperties;
+import eu.ztsh.lfr.model.Averages;
 import eu.ztsh.lfr.model.DataRow;
 import eu.ztsh.lfr.model.FileProcessingException;
 import eu.ztsh.lfr.model.Temperatures;
@@ -9,15 +10,20 @@ import eu.ztsh.lfr.model.events.FileProcessedEvent;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.context.event.ApplicationReadyEvent;
+import org.springframework.context.ApplicationEvent;
 import org.springframework.context.ApplicationEventPublisher;
 import org.springframework.context.event.EventListener;
 import org.springframework.scheduling.annotation.Async;
+import org.springframework.scheduling.annotation.Scheduled;
 import org.springframework.stereotype.Service;
 
 import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Paths;
+import java.util.concurrent.ConcurrentLinkedQueue;
 import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.function.Predicate;
 import java.util.stream.Stream;
 
@@ -28,6 +34,9 @@ public class FileLoadingService {
     private final DataProperties dataProperties;
     private final ApplicationEventPublisher eventPublisher;
 
+    private final ConcurrentLinkedQueue<ApplicationEvent> queue = new ConcurrentLinkedQueue<>();
+    private final AtomicBoolean working = new AtomicBoolean();
+
     @Autowired
     public FileLoadingService(DataProperties dataProperties, ApplicationEventPublisher eventPublisher) {
         this.dataProperties = dataProperties;
@@ -35,8 +44,32 @@ public class FileLoadingService {
     }
 
     @Async
-    @EventListener(FileModifiedEvent.class)
+    @EventListener({FileModifiedEvent.class, ApplicationReadyEvent.class})
-    public void onFileModified() {
+    public void onFileModified(ApplicationEvent event) {
+        queue.add(event);
+    }
+
+    @Scheduled(fixedRate=500)
+    void runTask() {
+        if (working.get()) {
+            return;
+        }
+        ApplicationEvent event;
+        log.debug("{} events queued", queue.size());
+        do {
+            // process only last
+            event = queue.poll();
+        } while (!queue.isEmpty());
+        if (event != null) {
+            log.info("Processing event: {}", event.getClass().getSimpleName());
+            working.set(true);
+            var result = processFile();
+            eventPublisher.publishEvent(new FileProcessedEvent(result));
+            working.set(false);
+        }
+    }
+
+    private Averages processFile() {
         var start = System.currentTimeMillis();
         log.debug("Processing file");
         final Temperatures model = new Temperatures();
@@ -59,7 +92,7 @@ public class FileLoadingService {
         log.atInfo().setMessage("Elapsed time: {}:{}").addArgument(TimeUnit.MILLISECONDS.toMinutes(millis))
             .addArgument(() -> String.format("%02d", TimeUnit.MILLISECONDS.toSeconds(millis) % 60))
             .log();
-        eventPublisher.publishEvent(new FileProcessedEvent(model.getAverages()));
+        return model.getAverages();
     }
 
 }

src/main/java/eu/ztsh/lfr/core/impl/files/WatcherService.java

@@ -66,7 +66,7 @@ public class WatcherService {
             if (maybeLastEvent.isPresent()) {
                 var lastEvent = maybeLastEvent.get();
                 log.info("Got event of kind:{}", lastEvent.kind());
-                eventPublisher.publishEvent(new FileModifiedEvent(System.currentTimeMillis()));
+                eventPublisher.publishEvent(new FileModifiedEvent(this));
             } else {
                 log.trace("Got event for not watched file");
             }

src/main/java/eu/ztsh/lfr/model/events/FileModifiedEvent.java

@@ -1,5 +1,11 @@
 package eu.ztsh.lfr.model.events;
 
-public record FileModifiedEvent(long timestamp) {
+import org.springframework.context.ApplicationEvent;
+
+public class FileModifiedEvent extends ApplicationEvent {
+
+    public FileModifiedEvent(Object source) {
+        super(source);
+    }
 
 }

src/test/java/eu/ztsh/lfr/core/impl/files/FileLoadingServiceTest.java

@@ -6,6 +6,7 @@ import eu.ztsh.lfr.model.events.FileProcessedEvent;
 import org.junit.jupiter.api.Test;
 import org.mockito.ArgumentCaptor;
 import org.mockito.Mockito;
+import org.springframework.context.ApplicationEvent;
 import org.springframework.context.ApplicationEventPublisher;
 
 import java.io.IOException;
@@ -22,7 +23,8 @@ class FileLoadingServiceTest {
     void successfulRunTest() {
         var captor = ArgumentCaptor.forClass(FileProcessedEvent.class);
         var service = createFileLoadingService("success.csv");
-        assertThatNoException().isThrownBy(service::onFileModified);
+        service.onFileModified(new TestEvent());
+        assertThatNoException().isThrownBy(service::runTask);
         Mockito.verify(eventPublisher, Mockito.times(1))
             .publishEvent(captor.capture());
         var averages = captor.getValue().averages();
@@ -39,7 +41,8 @@ class FileLoadingServiceTest {
     @Test
     void notExistingFileTest() {
         var service = createFileLoadingService("not-existing.csv");
-        assertThatThrownBy(service::onFileModified)
+        service.onFileModified(new TestEvent());
+        assertThatThrownBy(service::runTask)
             .isInstanceOf(FileProcessingException.class)
             .hasRootCauseInstanceOf(IOException.class);
         Mockito.verifyNoInteractions(eventPublisher);
@@ -48,7 +51,8 @@ class FileLoadingServiceTest {
     @Test
     void malformedFileTest() {
         var service = createFileLoadingService("malformed.csv");
-        assertThatThrownBy(service::onFileModified)
+        service.onFileModified(new TestEvent());
+        assertThatThrownBy(service::runTask)
             .isInstanceOf(FileProcessingException.class)
             .hasMessage("Error in line Warszawa;2018-09-21 11:17:42.31833.27")
             .hasRootCauseInstanceOf(ArrayIndexOutOfBoundsException.class);
@@ -59,4 +63,12 @@ class FileLoadingServiceTest {
         return new FileLoadingService(new DataProperties("src/test/resources/" + path), eventPublisher);
     }
 
+    private static class TestEvent extends ApplicationEvent {
+
+        public TestEvent() {
+            super("TestEvent");
+        }
+
+    }
+
 }