From bed3a4e3c936683740b4396c43092f0b1be8abbd Mon Sep 17 00:00:00 2001
From: Jerry Yan <792602257@qq.com>
Date: Thu, 23 Oct 2025 21:24:58 +0800
Subject: [PATCH] =?UTF-8?q?feat(printer):=20=E5=AE=9E=E7=8E=B0=E4=BB=BB?=
 =?UTF-8?q?=E5=8A=A1=E7=8A=B6=E6=80=81=E7=9A=84=E5=8E=9F=E5=AD=90=E6=80=A7?=
 =?UTF-8?q?=E6=9B=B4=E6=96=B0=E4=B8=8E=E5=90=8C=E6=AD=A5=E9=94=81=E6=9C=BA?=
 =?UTF-8?q?=E5=88=B6?=
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- 添加 compareAndSetTaskStatus 方法以支持基于期望状态的任务更新
- 引入 ReentrantLock 实现任务同步处理，防止并发冲突
- 在 XML 映射文件中定义 compareAndSetTaskStatus 的 SQL 更新语句
- 定义任务状态常量：TASK_STATUS_PENDING 和 TASK_STATUS_PROCESSING
- 优化任务获取逻辑，确保任务状态在处理前正确更新为 PROCESSING
---
 .../com/ycwl/basic/mapper/PrinterMapper.java  |  6 +++-
 .../printer/impl/PrinterServiceImpl.java      | 30 +++++++++++++++----
 src/main/resources/mapper/PrinterMapper.xml   |  7 ++++-
 3 files changed, 36 insertions(+), 7 deletions(-)

diff --git a/src/main/java/com/ycwl/basic/mapper/PrinterMapper.java b/src/main/java/com/ycwl/basic/mapper/PrinterMapper.java
index de6d71ec..a4fc788d 100644
--- a/src/main/java/com/ycwl/basic/mapper/PrinterMapper.java
+++ b/src/main/java/com/ycwl/basic/mapper/PrinterMapper.java
@@ -28,6 +28,10 @@ public interface PrinterMapper {
 
     int updateTaskStatus(@Param("id") Integer id, @Param("status") Integer status);
 
+    int compareAndSetTaskStatus(@Param("id") Integer id,
+                                @Param("expectStatus") Integer expectStatus,
+                                @Param("newStatus") Integer newStatus);
+
     PrintTaskEntity getTaskById(Integer id);
 
     List<PrinterResp> listByScenicId(@Param("scenicId") Long scenicId);
@@ -51,4 +55,4 @@ public interface PrinterMapper {
     void updateUserPhotoListToPrinter(Long memberId, Long scenicId, Integer printerId);
 
     List<MemberPrintResp> listRelationByOrderId(Long orderId);
-}
\ No newline at end of file
+}
diff --git a/src/main/java/com/ycwl/basic/service/printer/impl/PrinterServiceImpl.java b/src/main/java/com/ycwl/basic/service/printer/impl/PrinterServiceImpl.java
index 9cebb8fd..08f0e5e2 100644
--- a/src/main/java/com/ycwl/basic/service/printer/impl/PrinterServiceImpl.java
+++ b/src/main/java/com/ycwl/basic/service/printer/impl/PrinterServiceImpl.java
@@ -69,6 +69,8 @@ import java.util.Map;
 import java.util.Objects;
 import java.util.UUID;
 import java.util.concurrent.TimeUnit;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 import java.util.stream.Collectors;
 
 @Slf4j
@@ -151,11 +153,26 @@ public class PrinterServiceImpl implements PrinterService {
             printer.setPrinters(printersStr);
             printerMapper.update(printer);
         }
-        PrintTaskResp task = printerMapper.findTaskByPrinterId(printer.getId());
-        if (task == null) {
-            return Collections.emptyList();
+        syncTaskLock.lock();
+        try {
+            while (true) {
+                PrintTaskResp task = printerMapper.findTaskByPrinterId(printer.getId());
+                if (task == null) {
+                    return Collections.emptyList();
+                }
+                int updatedRows = printerMapper.compareAndSetTaskStatus(
+                        task.getId(),
+                        TASK_STATUS_PENDING,
+                        TASK_STATUS_PROCESSING
+                );
+                if (updatedRows == 1) {
+                    task.setStatus(TASK_STATUS_PROCESSING);
+                    return Collections.singletonList(task);
+                }
+            }
+        } finally {
+            syncTaskLock.unlock();
         }
-        return Collections.singletonList(task);
     }
 
     @Override
@@ -427,6 +444,9 @@ public class PrinterServiceImpl implements PrinterService {
     @Autowired
     private RedisTemplate<String, String> redisTemplate;
     private static final String USER_PHOTO_LIST_TO_PRINTER = "USER_PHOTO_LIST_TO_PRINTER:";
+    private static final int TASK_STATUS_PENDING = 0;
+    private static final int TASK_STATUS_PROCESSING = 3;
+    private final Lock syncTaskLock = new ReentrantLock();
 
     @Override
     public void setUserIsBuyItem(Long memberId, Long id, Long orderId) {
@@ -550,4 +570,4 @@ public class PrinterServiceImpl implements PrinterService {
             printTaskMapper.insertTask(task);
         });
     }
-}
\ No newline at end of file
+}
diff --git a/src/main/resources/mapper/PrinterMapper.xml b/src/main/resources/mapper/PrinterMapper.xml
index 54177f37..567c5eb6 100644
--- a/src/main/resources/mapper/PrinterMapper.xml
+++ b/src/main/resources/mapper/PrinterMapper.xml
@@ -152,6 +152,11 @@
     <update id="updateTaskStatus">
         UPDATE print_task SET status = #{status}, update_time = NOW() WHERE id = #{id}
     </update>
+    <update id="compareAndSetTaskStatus">
+        UPDATE print_task
+        SET status = #{newStatus}, update_time = NOW()
+        WHERE id = #{id} AND status = #{expectStatus}
+    </update>
     <update id="setPhotoCropped">
         UPDATE member_print SET crop_url = #{url}, update_time = NOW(), print_url = null WHERE id = #{id}
     </update>
@@ -172,4 +177,4 @@
     <delete id="deleteUserPhoto">
         DELETE FROM member_print WHERE member_id = #{memberId} AND scenic_id = #{scenicId} AND id = #{relationId} LIMIT 1;
     </delete>
-</mapper>
\ No newline at end of file
+</mapper>