[Fix] 재지원 순번 계산 기준 수정

src/main/java/com/jobdri/jobdri_api/domain/mockapply/entity/MockApplySequence.java

@@ -0,0 +1,58 @@
+package com.jobdri.jobdri_api.domain.mockapply.entity;
+
+import jakarta.persistence.*;
+import lombok.AccessLevel;
+import lombok.AllArgsConstructor;
+import lombok.Builder;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+
+@Entity
+@Getter
+@NoArgsConstructor(access = AccessLevel.PROTECTED)
+@AllArgsConstructor(access = AccessLevel.PRIVATE)
+@Builder(access = AccessLevel.PRIVATE)
+@Table(
+        name = "mock_apply_sequences",
+        uniqueConstraints = @UniqueConstraint(
+                name = "uk_mock_apply_sequences_key",
+                columnNames = {"user_id", "company_id", "detail_classification_id"}
+        )
+)
+public class MockApplySequence {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private Long id;
+
+    @Column(name = "user_id", nullable = false)
+    private Long userId;
+
+    @Column(name = "company_id", nullable = false)
+    private Long companyId;
+
+    @Column(name = "detail_classification_id", nullable = false)
+    private Long detailClassificationId;
+
+    @Column(nullable = false)
+    private int lastSequence;
+
+    public static MockApplySequence create(
+            Long userId,
+            Long companyId,
+            Long detailClassificationId,
+            int lastSequence
+    ) {
+        return MockApplySequence.builder()
+                .userId(userId)
+                .companyId(companyId)
+                .detailClassificationId(detailClassificationId)
+                .lastSequence(lastSequence)
+                .build();
+    }
+
+    public int incrementAndGet() {
+        lastSequence++;
+        return lastSequence;
+    }
+}

src/main/java/com/jobdri/jobdri_api/domain/mockapply/repository/MockApplyRepository.java

@@ -12,6 +12,19 @@ public interface MockApplyRepository extends JpaRepository<MockApply, Long> {
     List<MockApply> findAllByJobPostingId(Long jobPostingId);
     long countByUserIdAndJobPostingId(Long userId, Long jobPostingId);
 
+    @Query("""
+            select coalesce(max(ma.sequence), 0)
+            from MockApply ma
+            where ma.user.id = :userId
+              and ma.jobPosting.company.id = :companyId
+              and ma.jobPosting.detailClassification.id = :detailClassificationId
+            """)
+    int findMaxSequenceByUserIdAndCompanyIdAndDetailClassificationId(
+            @Param("userId") Long userId,
+            @Param("companyId") Long companyId,
+            @Param("detailClassificationId") Long detailClassificationId
+    );
+
     default int calculateSequence(MockApply mockApply) {
         if (mockApply.getSequence() != null && mockApply.getSequence() > 0) {
             return mockApply.getSequence();

src/main/java/com/jobdri/jobdri_api/domain/mockapply/repository/MockApplySequenceRepository.java

@@ -0,0 +1,27 @@
+package com.jobdri.jobdri_api.domain.mockapply.repository;
+
+import com.jobdri.jobdri_api.domain.mockapply.entity.MockApplySequence;
+import jakarta.persistence.LockModeType;
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.Lock;
+import org.springframework.data.jpa.repository.Query;
+import org.springframework.data.repository.query.Param;
+
+import java.util.Optional;
+
+public interface MockApplySequenceRepository extends JpaRepository<MockApplySequence, Long> {
+
+    @Lock(LockModeType.PESSIMISTIC_WRITE)
+    @Query("""
+            select mas
+            from MockApplySequence mas
+            where mas.userId = :userId
+              and mas.companyId = :companyId
+              and mas.detailClassificationId = :detailClassificationId
+            """)
+    Optional<MockApplySequence> findByKeyForUpdate(
+            @Param("userId") Long userId,
+            @Param("companyId") Long companyId,
+            @Param("detailClassificationId") Long detailClassificationId
+    );
+}

src/main/java/com/jobdri/jobdri_api/domain/mockapply/service/MockApplySequenceService.java

@@ -0,0 +1,37 @@
+package com.jobdri.jobdri_api.domain.mockapply.service;
+
+import com.jobdri.jobdri_api.domain.mockapply.entity.MockApplySequence;
+import com.jobdri.jobdri_api.domain.mockapply.repository.MockApplyRepository;
+import com.jobdri.jobdri_api.domain.mockapply.repository.MockApplySequenceRepository;
+import lombok.RequiredArgsConstructor;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Propagation;
+import org.springframework.transaction.annotation.Transactional;
+
+@Service
+@RequiredArgsConstructor
+public class MockApplySequenceService {
+
+    private final MockApplySequenceRepository mockApplySequenceRepository;
+    private final MockApplyRepository mockApplyRepository;
+
+    @Transactional(propagation = Propagation.REQUIRES_NEW)
+    public int allocate(Long userId, Long companyId, Long detailClassificationId) {
+        MockApplySequence sequence = mockApplySequenceRepository
+                .findByKeyForUpdate(userId, companyId, detailClassificationId)
+                .orElseGet(() -> mockApplySequenceRepository.saveAndFlush(
+                        MockApplySequence.create(
+                                userId,
+                                companyId,
+                                detailClassificationId,
+                                mockApplyRepository.findMaxSequenceByUserIdAndCompanyIdAndDetailClassificationId(
+                                        userId,
+                                        companyId,
+                                        detailClassificationId
+                                )
+                        )
+                ));
+
+        return sequence.incrementAndGet();
+    }
+}

src/main/java/com/jobdri/jobdri_api/domain/mockapply/service/MockApplyService.java

@@ -40,6 +40,7 @@
 @Transactional(readOnly = true)
 public class MockApplyService {
     private static final int SEQUENCE_SAVE_MAX_RETRY = 5;
+    private static final int SEQUENCE_ALLOCATE_MAX_RETRY = 5;
     private static final String SEQUENCE_UNIQUE_CONSTRAINT = "uk_mock_apply_user_posting_sequence";
     private static final String UNIQUE_VIOLATION_SQL_STATE = "23505";
 
@@ -50,6 +51,7 @@ public class MockApplyService {
     private final JobPostingService jobPostingService;
     private final UserService userService;
     private final MockApplyPersistenceService mockApplyPersistenceService;
+    private final MockApplySequenceService mockApplySequenceService;
 
     @Transactional(propagation = Propagation.NOT_SUPPORTED)
     @AuditLogEvent(action = "MOCK_APPLY_CREATE", targetType = "MOCK_APPLY", targetId = "#result.mockApplyId()")
@@ -201,10 +203,31 @@ private int resolveSequence(User user, JobPosting jobPosting, Integer requestedS
         if (isPositiveSequence(requestedSequence)) {
             return requestedSequence;
         }
-        return Math.toIntExact(mockApplyRepository.countByUserIdAndJobPostingId(
-                user.getId(),
-                jobPosting.getId()
-        )) + 1;
+        return allocateSequence(user, jobPosting);
+    }
+
+    private int allocateSequence(User user, JobPosting jobPosting) {
+        for (int attempt = 0; attempt < SEQUENCE_ALLOCATE_MAX_RETRY; attempt++) {
+            try {
+                return mockApplySequenceService.allocate(
+                        user.getId(),
+                        jobPosting.getCompany().getId(),
+                        jobPosting.getDetailClassification().getId()
+                );
+            } catch (DataIntegrityViolationException e) {
+                if (attempt == SEQUENCE_ALLOCATE_MAX_RETRY - 1) {
+                    throw new GeneralException(
+                            GeneralErrorCode.INTERNAL_SERVER_ERROR,
+                            "모의 서류 지원 순번 할당에 실패했습니다."
+                    );
+                }
+            }
+        }
+
+        throw new GeneralException(
+                GeneralErrorCode.INTERNAL_SERVER_ERROR,
+                "모의 서류 지원 순번 할당에 실패했습니다."
+        );
     }
 
     private boolean isPositiveSequence(Integer sequence) {

src/test/java/com/jobdri/jobdri_api/domain/mockapply/service/MockApplyServiceTest.java

@@ -118,6 +118,24 @@ void createActualApplyWithRequestedSequence() {
         assertThat(sequenceResponse.totalCount()).isEqualTo(3);
     }
 
+    @Test
+    @DisplayName("같은 회사와 직무의 다른 공고로 재지원하면 다음 순번을 저장한다")
+    void createActualApplySequencesAcrossSameCompanyAndDetailJobPostings() {
+        User user = saveUser("actual-apply-retry-sequence@example.com");
+        Company company = saveCompany("재지원 기업 " + UUID.randomUUID(), CompanySize.MEDIUM);
+        DetailClassification detailClassification = saveDetailClassification("백엔드 개발");
+        JobPosting firstJobPosting = saveJobPosting(user, company, detailClassification, "첫 번째 JD");
+        JobPosting secondJobPosting = saveJobPosting(user, company, detailClassification, "복제된 JD");
+
+        MockApplyCreateResponse firstResponse = mockApplyService.createActualApply(user, firstJobPosting.getId());
+        MockApplyCreateResponse secondResponse = mockApplyService.createActualApply(user, secondJobPosting.getId());
+
+        MockApply secondMockApply = mockApplyRepository.findById(secondResponse.mockApplyId()).orElseThrow();
+        assertThat(firstResponse.sequence()).isEqualTo(1);
+        assertThat(secondResponse.sequence()).isEqualTo(2);
+        assertThat(secondMockApply.getSequence()).isEqualTo(2);
+    }
+
     @Test
     @DisplayName("요청 순번이 0 이하이면 다음 유효 순번을 저장한다")
     void createActualApplyIgnoresNonPositiveRequestedSequence() {
@@ -391,6 +409,22 @@ private JobPosting saveJobPosting(User user, String detailName) {
         });
     }
 
+    private JobPosting saveJobPosting(
+            User user,
+            Company company,
+            DetailClassification detailClassification,
+            String task
+    ) {
+        return inNewTransaction(() -> jobPostingRepository.save(JobPosting.create(
+                userRepository.findById(user.getId()).orElseThrow(),
+                companyRepository.findById(company.getId()).orElseThrow(),
+                detailClassificationRepository.findById(detailClassification.getId()).orElseThrow(),
+                task,
+                "자격 요건",
+                "우대 사항"
+        )));
+    }
+
     private DetailClassification saveDetailClassification(String detailName) {
         return inNewTransaction(() -> saveDetailClassificationInCurrentTransaction(detailName));
     }