show progress when parsing homepage

src/main/java/internal/hw/crawler/commands/CrawlCommand.java

@@ -4,6 +4,7 @@ import internal.hw.crawler.models.Article;
 import internal.hw.crawler.repositories.ArticleRepository;
 import internal.hw.crawler.strategies.crawl.CrawlStrategy;
 import internal.hw.crawler.strategies.crawl.CrawlStrategyFactory;
+import internal.hw.crawler.strategies.crawl.CrawlUtils;
 import internal.hw.crawler.views.CommandOutput;
 import org.jsoup.Jsoup;
 import org.jsoup.nodes.Document;
@@ -43,8 +44,14 @@ public class CrawlCommand implements Command {
         }
 
         Document doc = Jsoup.connect(url.toString()).timeout(5000).get();
+        CrawlUtils.setProgressCallback(msg -> System.out.print("\r" + msg));
+        try {
             List<Article> articles = strategy.parse(url, doc);
+            System.out.println();
             articles.stream().filter(Objects::nonNull).forEach(repository::add);
             out.success(String.format("Crawled %d articles from %s", articles.size(), urlRaw));
+        } finally {
+            CrawlUtils.clearProgressCallback();
+        }
     }
 }

src/main/java/internal/hw/crawler/strategies/crawl/CrawlUtils.java

@@ -14,25 +14,44 @@ import java.util.Objects;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
+import java.util.concurrent.atomic.AtomicInteger;
 import java.util.function.BiFunction;
+import java.util.function.Consumer;
 import java.util.regex.Pattern;
 import java.util.stream.Collectors;
 
 public class CrawlUtils {
     private static final Logger log = LoggerFactory.getLogger(CrawlUtils.class);
     private static final int THREAD_POOL_SIZE = 4;
+    private static final ThreadLocal<Consumer<String>> progressCallback = new ThreadLocal<>();
+
+    public static void setProgressCallback(Consumer<String> callback) {
+        progressCallback.set(callback);
+    }
+
+    public static void clearProgressCallback() {
+        progressCallback.remove();
+    }
 
     public static List<Article> parseHomepage(Document doc, Pattern idRegex,
                                               BiFunction<URL, Document, Article> singleParser) {
         HttpCrawler crawler = new HttpCrawler();
-        ExecutorService executor = Executors.newFixedThreadPool(THREAD_POOL_SIZE);
-        List<CompletableFuture<Article>> futures = new ArrayList<>();
+        Consumer<String> callback = progressCallback.get();
 
+        List<String> hrefs = new ArrayList<>();
         for (Element link : doc.getElementsByTag("a")) {
             String href = link.absUrl("href");
             if (href.isEmpty()) continue;
             if (!idRegex.matcher(href).find()) continue;
+            hrefs.add(href);
+        }
+
+        int total = hrefs.size();
+        AtomicInteger done = new AtomicInteger(0);
+        ExecutorService executor = Executors.newFixedThreadPool(THREAD_POOL_SIZE);
+        List<CompletableFuture<Article>> futures = new ArrayList<>(total);
 
+        for (String href : hrefs) {
             futures.add(CompletableFuture.supplyAsync(() -> {
                 try {
                     URL articleUrl = URI.create(href).toURL();
@@ -41,6 +60,11 @@ public class CrawlUtils {
                 } catch (Exception e) {
                     log.warn("Failed to fetch article: {}", href, e);
                     return null;
+                } finally {
+                    int completed = done.incrementAndGet();
+                    if (callback != null) {
+                        callback.accept("Progress: " + completed + "/" + total);
+                    }
                 }
             }, executor));
         }