Reserve SQLite writer before reading subscription event receipts

src/main/java/com/lion/lionwebsite/Dao/normal/SubscriptionEventMapper.java

@@ -7,6 +7,10 @@ import org.apache.ibatis.annotations.*;
 
 @Mapper
 public interface SubscriptionEventMapper {
+    /** Reserve SQLite's writer before the receipt read; a deferred read-to-write upgrade can fail immediately. */
+    @Update("update subscription_event_receipt set ingested_at=ingested_at where 0")
+    void reserveWriter();
+
     @Select("select fingerprint from subscription_event_receipt where event_id=#{eventId}")
     String fingerprint(String eventId);
 

src/main/java/com/lion/lionwebsite/Service/SubscriptionEventService.java

@@ -123,6 +123,7 @@ public class SubscriptionEventService {
         try {
             // Return acknowledgements only after execute has returned and the entire transaction committed.
             List<String> acknowledged = transactions.execute(status -> {
+                events.reserveWriter();
                 List<String> ids = new ArrayList<>();
                 for (SubscriptionEvent event : batch) if (persist(event, "standby", null)) ids.add(event.getEventId());
                 return ids;
@@ -133,6 +134,7 @@ public class SubscriptionEventService {
 
     public void recordPrimary(SubscriptionEvent event, SubBind binding) {
         transactions.executeWithoutResult(status -> {
+            events.reserveWriter();
             if (!persist(event, "primary", binding)) throw new IllegalStateException("subscription user unavailable");
         });
     }