Added three attempts to load the RSS feed in case the connection time…

…s out or fails for any other reason.

src/main/java/dev/dobicinaitis/feedreader/services/FeedReaderService.java

@@ -4,17 +4,31 @@
 import com.apptasticsoftware.rssreader.RssReader;
 import com.apptasticsoftware.rssreader.util.ItemComparator;
 import dev.dobicinaitis.feedreader.exceptions.FeedReaderRuntimeException;
-import lombok.RequiredArgsConstructor;
+import lombok.AllArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
 
+import javax.net.ssl.SSLContext;
 import java.io.IOException;
+import java.net.http.HttpClient;
+import java.security.KeyManagementException;
+import java.security.NoSuchAlgorithmException;
+import java.time.Duration;
 import java.util.List;
 
 @Slf4j
-@RequiredArgsConstructor
+@AllArgsConstructor
 public class FeedReaderService {
 
+    private static final int CONNECTION_TIMEOUT_IN_SECONDS = 10;
+    private static final int FEED_READ_RETRY_COUNT = 3;
+
     private final String url;
+    private final HttpClient httpClient;
+
+    public FeedReaderService(String url) {
+        this.url = url;
+        this.httpClient = createHttpClient(CONNECTION_TIMEOUT_IN_SECONDS);
+    }
 
 
     /**
@@ -23,14 +37,55 @@ public class FeedReaderService {
      * @return list of RSS feed items
      */
     public List<Item> getItems() {
-        final RssReader rssReader = new RssReader();
+        return loadItems(FEED_READ_RETRY_COUNT).stream()
+                .sorted(ItemComparator.oldestItemFirst())
+                .toList();
+    }
+
+    /**
+     * Loads items from the RSS feed URL.
+     *
+     * @param retriesLeft number of attempts to load the RSS feed
+     * @return list of RSS feed items
+     */
+    protected List<Item> loadItems(int retriesLeft) {
+        final RssReader rssReader = new RssReader(httpClient);
+        log.debug("Loading items from the RSS feed.");
+        while (true) {
+            try {
+                return rssReader.read(url).toList();
+            } catch (IOException e) {
+                log.error("Could not load the RSS feed, reason {}", e.getMessage());
+                retriesLeft--;
+                if (retriesLeft == 0) {
+                    throw new FeedReaderRuntimeException(e);
+                }
+            }
+            log.info("Retrying to load the RSS feed, retries left: {}", retriesLeft);
+        }
+    }
+
+    /**
+     * Creates a new HTTP client with a custom connection timeout.
+     *
+     * @return HTTP client
+     */
+    protected static HttpClient createHttpClient(int timeoutInSeconds) {
+        HttpClient client;
         try {
-            return rssReader.read(url)
-                    .sorted(ItemComparator.oldestItemFirst())
-                    .toList();
-        } catch (IOException e) {
-            log.error("Could not load items from the RSS feed.");
-            throw new FeedReaderRuntimeException(e);
+            var sslContext = SSLContext.getInstance("TLSv1.3");
+            sslContext.init(null, null, null);
+            client = HttpClient.newBuilder()
+                    .sslContext(sslContext)
+                    .connectTimeout(Duration.ofSeconds(timeoutInSeconds))
+                    .followRedirects(HttpClient.Redirect.ALWAYS)
+                    .build();
+        } catch (NoSuchAlgorithmException | KeyManagementException e) {
+            client = HttpClient.newBuilder()
+                    .connectTimeout(Duration.ofSeconds(timeoutInSeconds))
+                    .followRedirects(HttpClient.Redirect.ALWAYS)
+                    .build();
         }
+        return client;
     }
 }

src/test/java/dev/dobicinaitis/feedreader/services/FeedReaderServiceTest.java

@@ -4,11 +4,15 @@
 import dev.dobicinaitis.feedreader.helpers.TestFeedServer;
 import org.junit.jupiter.api.AfterAll;
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.Timeout;
+
+import java.net.http.HttpClient;
 
 import static org.junit.jupiter.api.Assertions.*;
 
 class FeedReaderServiceTest {
 
+    private static final String NON_ROUTABLE_IP = "10.255.255.1";
     private static final TestFeedServer feedServer = new TestFeedServer();
 
     @AfterAll
@@ -36,5 +40,33 @@ void shouldThrowFeedReaderRuntimeExceptionWhenFeedIsUnavailable() {
         final FeedReaderService feedReader = new FeedReaderService(feedUrl);
         assertThrows(FeedReaderRuntimeException.class, feedReader::getItems, "Should throw FeedReaderRuntimeException");
     }
+
+    @Test
+    @Timeout(3)
+    void shouldRespectHttpRequestTimeoutSettings() {
+        // given
+        final int timeoutInSeconds = 1;
+        final int retryCount = 1;
+        final String feedUrl = "https://" + NON_ROUTABLE_IP;
+        final HttpClient httpClient = FeedReaderService.createHttpClient(timeoutInSeconds);
+        final FeedReaderService feedReader = new FeedReaderService(feedUrl, httpClient);
+        // when, then
+        assertThrows(FeedReaderRuntimeException.class, () -> feedReader.loadItems(retryCount), "Should throw FeedReaderRuntimeException");
+        // the timeout should occur after 1 second, so anything under 3 seconds is fine
+    }
+
+    @Test
+    @Timeout(5)
+    void shouldAttemptToLoadFeedMultipleTimes(){
+        // given
+        final int timeoutPerRequestInSeconds = 1;
+        final int retryCount = 3;
+        final String feedUrl = "https://" + NON_ROUTABLE_IP;
+        final HttpClient httpClient = FeedReaderService.createHttpClient(timeoutPerRequestInSeconds);
+        final FeedReaderService feedReader = new FeedReaderService(feedUrl, httpClient);
+        // when, then
+        assertThrows(FeedReaderRuntimeException.class, () -> feedReader.loadItems(retryCount), "Should throw FeedReaderRuntimeException");
+        // the timeout should occur after 3 seconds, so anything under 5 seconds is fine
+    }
 }