fix(lastleg): read committed order command replays after lock waits

lastleg-service/src/main/java/com/baiyue/lastleg/service/LastlegOrderCommandService.java

@@ -21,6 +21,7 @@ import com.fasterxml.jackson.databind.ObjectMapper;
 import jakarta.annotation.Resource;
 import org.springframework.http.HttpStatus;
 import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Isolation;
 import org.springframework.transaction.annotation.Transactional;
 import org.springframework.web.server.ResponseStatusException;
 
@@ -55,7 +56,9 @@ public class LastlegOrderCommandService {
     @Resource private InventoryCommandService inventory;
     @Resource private ObjectMapper objectMapper;
 
-    @Transactional
+    // Ownership is read before waiting for the order lock. Under MySQL repeatable
+    // read that snapshot can hide the preceding writer's idempotency record.
+    @Transactional(isolation = Isolation.READ_COMMITTED)
     public LastlegOrderCommandDtos.HoldResponse hold(String requestedCustomerId, long orderId,
                                                       String idempotencyKey,
                                                       LastlegOrderCommandDtos.HoldRequest request,
@@ -122,7 +125,7 @@ public class LastlegOrderCommandService {
         return response;
     }
 
-    @Transactional
+    @Transactional(isolation = Isolation.READ_COMMITTED)
     public LastlegOrderCommandDtos.ManualNodesResponse saveManualNodes(String requestedCustomerId, long orderId,
                                                                         String idempotencyKey,
                                                                         LastlegOrderCommandDtos.ManualNodesRequest request,

lastleg-service/src/test/java/com/baiyue/lastleg/inventory/command/InventoryHoldConcurrencyPersistenceTest.java

@@ -137,6 +137,32 @@ class InventoryHoldConcurrencyPersistenceTest {
         assertEquals(12,amount("available_packages")+amount("hold_packages")+amount("allocated_packages")+amount("picked_packages")+shipped);
         assertEquals(shipped,jdbc.queryForObject("SELECT COALESCE(-SUM(delta_packages),0) FROM ll_inventory_ledger WHERE business_type='SHIP'",Long.class));
     }
+    @Test void simultaneousDuplicateHoldAndReleaseAdvanceOnceAndKeepIndependentHold() throws Exception {
+        inventory.hold("C1","operator",move(22,2,"OTHER-HOLD"));
+        ExecutorService pool=Executors.newFixedThreadPool(2);
+        try {
+            for (boolean held : new boolean[]{true,false}) {
+                int version=held?0:1;
+                String key=held?"parallel-hold":"parallel-release";
+                var ready=new CountDownLatch(2);var start=new CountDownLatch(1);
+                Callable<LastlegOrderCommandDtos.HoldResponse> command=()->{
+                    ready.countDown();await(start);
+                    return orders.hold("C1",11,key,new LastlegOrderCommandDtos.HoldRequest(held,false,"quality",version),"operator","Operator");
+                };
+                var first=pool.submit(command);var second=pool.submit(command);
+                await(ready);start.countDown();
+                var response=first.get(8,TimeUnit.SECONDS);
+                assertEquals(response,second.get(8,TimeUnit.SECONDS));
+                assertEquals(version+1,response.version());
+                assertEquals(version+1,orderMapper.selectById(11L).getVersion());
+            }
+            assertEquals(2,count("ll_order_command_record"));
+            assertEquals(2,count("ll_order_hold_history"));
+            assertEquals(5,count("ll_inventory_operation"));
+            assertEquals(5,count("ll_inventory_ledger"));
+            assertEquals(10,amount("available_packages"));assertEquals(2,amount("hold_packages"));conserved(0);
+        } finally {pool.shutdownNow();assertTrue(pool.awaitTermination(10,TimeUnit.SECONDS));}
+    }
     @Test void secondHoldCycleMustMoveInventoryAgainAndNotReuseTheFirstCycle() {
         hold(true,0,"hold-one"); hold(false,1,"release-one"); hold(true,2,"hold-two");
         assertEquals(0,amount("available_packages")); assertEquals(12,amount("hold_packages"));

lastleg-service/src/test/java/com/baiyue/lastleg/service/LastlegOrderCommandServiceTest.java

@@ -66,6 +66,18 @@ class LastlegOrderCommandServiceTest {
         ReflectionTestUtils.setField(service, "objectMapper", JsonMapper.builder().findAndAddModules().build());
     }
 
+    @Test
+    void commandTransactionsReadCommittedAfterWaitingForTheOrderLock() throws Exception {
+        for (var entry : List.of(
+            new Object[]{"hold", LastlegOrderCommandDtos.HoldRequest.class},
+            new Object[]{"saveManualNodes", LastlegOrderCommandDtos.ManualNodesRequest.class})) {
+            var method=LastlegOrderCommandService.class.getMethod((String)entry[0],String.class,long.class,
+                String.class,(Class<?>)entry[1],String.class,String.class);
+            assertEquals(org.springframework.transaction.annotation.Isolation.READ_COMMITTED,
+                method.getAnnotation(org.springframework.transaction.annotation.Transactional.class).isolation());
+        }
+    }
+
     @Test
     void holdsOnlySelectedOrderWithVersionAndImmutableHistory() {
         LastlegOrder order = order(11L, 3);