TAN-989: Investigate and Fix LeetCode question error in prod

src/main/java/org/patinanetwork/codebloom/common/leetcode/LeetcodeClientException.java

@@ -1,12 +1,23 @@
 package org.patinanetwork.codebloom.common.leetcode;
 
+import lombok.Getter;
+
+@Getter
 public class LeetcodeClientException extends RuntimeException {
 
+    private final boolean notFound;
+
     public LeetcodeClientException(final String message) {
+        this(message, false);
+    }
+
+    public LeetcodeClientException(final String message, final boolean notFound) {
         super(message);
+        this.notFound = notFound;
     }
 
     public LeetcodeClientException(final String message, final Throwable e) {
         super(message, e);
+        this.notFound = false;
     }
 }

src/main/java/org/patinanetwork/codebloom/common/leetcode/LeetcodeClientImpl.java

@@ -133,7 +133,7 @@
     @Override
     @Retry(name = "leetcodeClient")
     @CircuitBreaker(name = "leetcodeClient")
     public LeetcodeQuestion findQuestionBySlug(final String slug) {
         String requestBody;
         try {
             requestBody = SelectProblemQuery.body(slug);
@@ -159,6 +159,14 @@
 
             JsonNode node = mapper.readTree(body);
             JsonNode questionNode = node.path("data").path("question");
+            if (!questionNode.isObject()
+                    && node.hasNonNull("errors")
+                    && !node.path("errors").isEmpty()) {
+                throw new LeetcodeClientException("LeetCode returned GraphQL errors for slug " + slug);
+            }
+            if (node.path("data").isObject() && node.path("data").has("question") && questionNode.isNull()) {
+                throw new LeetcodeClientException("LeetCode returned no question for slug " + slug, true);
+            }
             if (!questionNode.isObject()) {
                 throw new LeetcodeClientException("LeetCode returned no question data");
             }
@@ -205,6 +213,12 @@
                     .acceptanceRate(acRate)
                     .topics(tags)
                     .build();
+        } catch (LeetcodeClientException e) {
+            if (e.isNotFound()) {
+                throw e;
+            }
+            errorCounter().increment();
+            throw new LeetcodeClientException("Error fetching the API", e);
         } catch (InterruptedException e) {
             errorCounter().increment();
             Thread.currentThread().interrupt();

src/main/java/org/patinanetwork/codebloom/scheduled/leetcode/AttachTagsToExistingQuestion.java

@@ -9,6 +9,7 @@
 import org.patinanetwork.codebloom.common.db.repos.question.QuestionRepository;
 import org.patinanetwork.codebloom.common.db.repos.question.topic.QuestionTopicRepository;
 import org.patinanetwork.codebloom.common.leetcode.LeetcodeClient;
+import org.patinanetwork.codebloom.common.leetcode.LeetcodeClientException;
 import org.patinanetwork.codebloom.common.leetcode.models.LeetcodeQuestion;
 import org.patinanetwork.codebloom.common.leetcode.throttled.ThrottledLeetcodeClient;
 import org.springframework.context.annotation.Profile;
@@ -44,12 +45,23 @@ void attachTagsToExistingQuestions() {
         }
 
         for (var question : questions) {
-            log.info("Updating question with id of {}", question.getId());
+            log.info("Updating question with id of {} and slug {}", question.getId(), question.getQuestionSlug());
             LeetcodeQuestion leetcodeQuestion;
             try {
                 leetcodeQuestion = leetcodeClient.findQuestionBySlug(question.getQuestionSlug());
             } catch (Exception e) {
-                log.error("LeetcodeClient threw an exception", e);
+                if (e instanceof LeetcodeClientException clientException && clientException.isNotFound()) {
+                    log.info(
+                            "Skipping topic lookup for question id {} and slug {} because it was not found",
+                            question.getId(),
+                            question.getQuestionSlug());
+                } else {
+                    log.error(
+                            "LeetcodeClient threw an exception for question id {} and slug {}",
+                            question.getId(),
+                            question.getQuestionSlug(),
+                            e);
+                }
                 continue;
             }
 
@@ -64,6 +76,11 @@ void attachTagsToExistingQuestions() {
 
                 questionTopicRepository.createQuestionTopic(newQuestionTopic);
             }
+            log.info(
+                    "Attached {} topics to question id {} and slug {}",
+                    leetcodeQuestion.getTopics().size(),
+                    question.getId(),
+                    question.getQuestionSlug());
         }
 
         log.info("This task is complete.");

src/main/java/org/patinanetwork/codebloom/scheduled/leetcode/LeetcodeQuestionProcessService.java

@@ -33,7 +33,7 @@
 @Profile("!ci | thread")
 public class LeetcodeQuestionProcessService {
 
-    private static final ReentrantLock LOCK = new ReentrantLock();
+    private final ReentrantLock lock = new ReentrantLock();
 
     private static final int MAX_JOBS_PER_RUN = 10;
     private static final long REQUESTS_OVER_TIME = 1L;
@@ -89,7 +89,7 @@ private List<Job> claimBatch(final int maxSize) {
     @Scheduled(initialDelay = 0, fixedDelay = 30, timeUnit = TimeUnit.MINUTES)
     @Async
     public CompletableFuture<Empty> drainQueue() {
-        if (!LOCK.tryLock()) {
+        if (!lock.tryLock()) {
             log.info("thread attempted to drain queue, but queue is already being drained.");
             return CompletableFuture.completedFuture(Empty.of());
         }
@@ -119,7 +119,7 @@ public CompletableFuture<Empty> drainQueue() {
                 }
             }
         } finally {
-            LOCK.unlock();
+            lock.unlock();
         }
         return CompletableFuture.completedFuture(Empty.of());
     }

src/test/java/org/patinanetwork/codebloom/common/leetcode/LeetcodeClientTest.java

@@ -50,6 +50,50 @@ void setup() {
         when(leetcodeAuthStealer.getCsrf()).thenReturn(null);
     }
 
+    @Test
+    void explicitNullQuestionIsNotFound() throws Exception {
+        when(httpResponse.statusCode()).thenReturn(200);
+        when(httpResponse.body()).thenReturn("{\"data\":{\"question\":null}}");
+        when(httpClient.send(any(HttpRequest.class), any(HttpResponse.BodyHandler.class)))
+                .thenReturn(httpResponse);
+
+        var error = assertThrows(LeetcodeClientException.class, () -> leetcodeClient.findQuestionBySlug("old-slug"));
+        assertTrue(error.isNotFound());
+        assertNull(meterRegistry.find("leetcode.client.exception").counter());
+    }
+
+    @ParameterizedTest
+    @ValueSource(
+            strings = {
+                "{\"data\":{\"question\":null},\"errors\":[{\"message\":\"Unauthorized\"}]}",
+                "{\"data\":{}}",
+                "{\"data\":null}",
+                "invalid json"
+            })
+    void unsuccessfulOrMalformedResponseIsNotNotFound(String body) throws Exception {
+        when(httpResponse.statusCode()).thenReturn(200);
+        when(httpResponse.body()).thenReturn(body);
+        when(httpClient.send(any(HttpRequest.class), any(HttpResponse.BodyHandler.class)))
+                .thenReturn(httpResponse);
+
+        var error = assertThrows(LeetcodeClientException.class, () -> leetcodeClient.findQuestionBySlug("example"));
+        assertFalse(error.isNotFound());
+        assertEquals(
+                1.0, meterRegistry.get("leetcode.client.exception").counter().count());
+    }
+
+    @ParameterizedTest
+    @ValueSource(ints = {403, 404, 429, 503})
+    void httpFailureDoesNotPermanentlyExcludeQuestion(int status) throws Exception {
+        when(httpResponse.statusCode()).thenReturn(status);
+        when(httpResponse.body()).thenReturn("{\"data\":{\"question\":null}}");
+        when(httpClient.send(any(HttpRequest.class), any(HttpResponse.BodyHandler.class)))
+                .thenReturn(httpResponse);
+
+        var error = assertThrows(LeetcodeClientException.class, () -> leetcodeClient.findQuestionBySlug("example"));
+        assertFalse(error.isNotFound());
+    }
+
     @Test
     void testFindQuestionBySlug() throws Exception {
         String responseJson = """

src/test/java/org/patinanetwork/codebloom/scheduled/leetcode/AttachTagsToExistingQuestionTest.java

@@ -17,6 +17,7 @@
 import org.patinanetwork.codebloom.common.db.models.question.Question;
 import org.patinanetwork.codebloom.common.db.repos.question.QuestionRepository;
 import org.patinanetwork.codebloom.common.db.repos.question.topic.QuestionTopicRepository;
+import org.patinanetwork.codebloom.common.leetcode.LeetcodeClientException;
 import org.patinanetwork.codebloom.common.leetcode.throttled.ThrottledLeetcodeClient;
 import org.patinanetwork.codebloom.common.time.StandardizedLocalDateTime;
 import org.slf4j.LoggerFactory;
@@ -68,8 +69,64 @@ function hello() {
                 .thenThrow(new RuntimeException("Expected!"));
 
         attachTagsToExistingQuestion.attachTagsToExistingQuestions();
+        attachTagsToExistingQuestion.attachTagsToExistingQuestions();
+        verify(leetcodeClient, times(2)).findQuestionBySlug(mockQuestion.getQuestionSlug());
+        verifyNoInteractions(questionTopicRepository);
         assertTrue(logWatcher.list.stream()
                 .anyMatch(log -> log.getLevel().equals(Level.ERROR)
-                        && log.getFormattedMessage().contains("LeetcodeClient threw an exception")));
+                        && log.getFormattedMessage().contains("LeetcodeClient threw an exception")
+                        && log.getFormattedMessage().contains(mockQuestion.getId())
+                        && log.getFormattedMessage().contains(mockQuestion.getQuestionSlug())));
+    }
+
+    @Test
+    void notFoundQuestionIsSkippedAndOtherQuestionsContinue() {
+        var missing = Question.builder().id("missing").questionSlug("old-slug").build();
+        var valid = Question.builder().id("valid").questionSlug("valid-slug").build();
+        when(questionRepository.getAllQuestionsWithNoTopics()).thenReturn(List.of(missing, valid));
+        when(leetcodeClient.findQuestionBySlug("old-slug"))
+                .thenThrow(new LeetcodeClientException("Question not found", true));
+        when(leetcodeClient.findQuestionBySlug("valid-slug"))
+                .thenReturn(org.patinanetwork.codebloom.common.leetcode.models.LeetcodeQuestion.builder()
+                        .topics(List.of())
+                        .build());
+
+        attachTagsToExistingQuestion.attachTagsToExistingQuestions();
+        attachTagsToExistingQuestion.attachTagsToExistingQuestions();
+
+        verify(leetcodeClient, times(2)).findQuestionBySlug("old-slug");
+        verify(leetcodeClient, times(2)).findQuestionBySlug("valid-slug");
+        verifyNoInteractions(questionTopicRepository);
+        assertTrue(logWatcher.list.stream()
+                .anyMatch(log -> log.getLevel().equals(Level.INFO)
+                        && log.getFormattedMessage().contains("Skipping topic lookup for question id missing")));
+        assertFalse(logWatcher.list.stream().anyMatch(log -> log.getLevel().equals(Level.ERROR)));
+    }
+
+    @Test
+    void attachesTopicsAndContinuesPastFailedQuestion() {
+        var failed = Question.builder().id("failed").questionSlug("old-slug").build();
+        var valid = Question.builder()
+                .id("valid")
+                .questionSlug("classes-with-at-least-5-students")
+                .build();
+        when(questionRepository.getAllQuestionsWithNoTopics()).thenReturn(List.of(failed, valid));
+        when(leetcodeClient.findQuestionBySlug("old-slug")).thenThrow(new RuntimeException("Missing"));
+        when(leetcodeClient.findQuestionBySlug(valid.getQuestionSlug()))
+                .thenReturn(org.patinanetwork.codebloom.common.leetcode.models.LeetcodeQuestion.builder()
+                        .topics(List.of(org.patinanetwork.codebloom.common.leetcode.models.LeetcodeTopicTag.builder()
+                                .name("Database")
+                                .slug("database")
+                                .build()))
+                        .build());
+
+        attachTagsToExistingQuestion.attachTagsToExistingQuestions();
+
+        verify(questionTopicRepository)
+                .createQuestionTopic(
+                        argThat(topic -> topic.getQuestionId().orElseThrow().equals("valid")
+                                && topic.getTopicSlug().equals("database")));
+        assertTrue(logWatcher.list.stream().anyMatch(log -> log.getFormattedMessage()
+                .contains("Attached 1 topics to question id valid and slug classes-with-at-least-5-students")));
     }
 }