Added logic to resolve crawlable short codes

module/Core/src/Repository/ShortUrlRepository.php

@@ -288,4 +288,28 @@ class ShortUrlRepository extends EntitySpecificationRepository implements ShortU
             $qb->andWhere($qb->expr()->isNull('s.domain'));
         }
     }
+
+    public function findCrawlableShortCodes(): iterable
+    {
+        $blockSize = 1000;
+        $qb = $this->getEntityManager()->createQueryBuilder();
+        $qb->select('DISTINCT s.shortCode')
+           ->from(ShortUrl::class, 's')
+           ->where($qb->expr()->eq('s.crawlable', ':crawlable'))
+           ->setParameter('crawlable', true)
+           ->setMaxResults($blockSize);
+
+        $page = 0;
+        do {
+            $qbClone = (clone $qb)->setFirstResult($blockSize * $page);
+            $iterator = $qbClone->getQuery()->toIterable();
+            $resultsFound = false;
+            $page++;
+
+            foreach ($iterator as ['shortCode' => $shortCode]) {
+                $resultsFound = true;
+                yield $shortCode;
+            }
+        } while ($resultsFound);
+    }
 }

module/Core/src/Repository/ShortUrlRepositoryInterface.php

@@ -41,4 +41,6 @@ interface ShortUrlRepositoryInterface extends ObjectRepository, EntitySpecificat
     public function findOneMatching(ShortUrlMeta $meta): ?ShortUrl;
 
     public function findOneByImportedUrl(ImportedShlinkUrl $url): ?ShortUrl;
+
+    public function findCrawlableShortCodes(): iterable;
 }

module/Core/src/Repository/VisitRepository.php

@@ -66,11 +66,11 @@ class VisitRepository extends EntitySpecificationRepository implements VisitRepo
 
         do {
             $qb = (clone $originalQueryBuilder)->andWhere($qb->expr()->gt('v.id', $lastId));
-            $iterator = $qb->getQuery()->iterate();
+            $iterator = $qb->getQuery()->toIterable();
             $resultsFound = false;
 
             /** @var Visit $visit */
-            foreach ($iterator as $key => [$visit]) {
+            foreach ($iterator as $key => $visit) {
                 $resultsFound = true;
                 yield $key => $visit;
             }