Bugfix (repeated changes to the same entry)

h2/src/main/org/h2/mvstore/db/TransactionStore.java

@@ -1062,11 +1062,7 @@ public class TransactionStore {
         }
         
         VersionedValue getValue(K key, long maxLog, VersionedValue data) {
-;
-// TODO test case for many updates within the same transaction
-// TODO detect loops
-            for (int i = 0; i < 1000; i++) {
-                int tx;
+            while (true) {
                 if (data == null) {
                     // doesn't exist or deleted by a committed transaction
                     return null;
@@ -1076,7 +1072,7 @@ public class TransactionStore {
                     // it is committed
                     return data;
                 }
-                tx = getTransactionId(id);
+                int tx = getTransactionId(id);
                 if (tx == transaction.transactionId) {
                     // added by this transaction
                     if (getLogId(id) < maxLog) {
@@ -1095,6 +1091,22 @@ public class TransactionStore {
                 } else {
                     data = (VersionedValue) d[2];
                 }
+                // verify this is either committed, 
+                // or the same transaction and earlier
+                if (data != null) {
+                    long id2 = data.operationId;
+                    if (id2 != 0) {
+                        int tx2 = getTransactionId(id2);
+                        if (tx2 != tx) {
+                            // a different transaction
+                            break;
+                        }
+                        if (getLogId(id2) > getLogId(id)) {
+                            // newer than before
+                            break;
+                        }
+                    }
+                }
             }
             throw DataUtils.newIllegalStateException(
                     DataUtils.ERROR_TRANSACTION_CORRUPT, 

h2/src/test/org/h2/test/store/TestTransactionStore.java

@@ -45,6 +45,7 @@ public class TestTransactionStore extends TestBase {
     @Override
     public void test() throws Exception {
         FileUtils.createDirectories(getBaseDir());
+        testRepeatedChange();
         testTransactionAge();
         testStopWhileCommitting();
         testGetModifiedMaps();
@@ -57,6 +58,30 @@ public class TestTransactionStore extends TestBase {
         testCompareWithPostgreSQL();
     }
     
+    private void testRepeatedChange() {
+        MVStore s;
+        TransactionStore ts;
+        s = MVStore.open(null);
+        ts = new TransactionStore(s);
+
+        Transaction tx0 = ts.begin();
+        TransactionMap<Integer, Integer> map0 = tx0.openMap("data");
+        map0.put(1, -1);
+        tx0.commit();
+
+        Transaction tx = ts.begin();
+        TransactionMap<Integer, Integer> map = tx.openMap("data");
+        for (int i = 0; i < 2000; i++) {
+            map.put(1, i);
+        }
+        
+        Transaction tx2 = ts.begin();
+        TransactionMap<Integer, Integer> map2 = tx2.openMap("data");
+        assertEquals(-1, map2.get(1).intValue());
+        
+        s.close();
+    }
+    
     private void testTransactionAge() throws Exception {
         MVStore s;
         TransactionStore ts;