Differentiate between rollback and read-only for KTI id

This commit makes KernelTransactionImplementation#closeTransaction() return
different values when transaction was rolled back or read only. It also
improves javadoc for KernelTransaction interface.

community/bolt/src/test/java/org/neo4j/bolt/v1/runtime/internal/ResetFuzzTest.java

@@ -249,7 +249,7 @@ public void failure()
         public long closeTransaction() throws TransactionFailureException
         {
             liveTransactions.decrementAndGet();
-            return NOT_COMMITTED;
+            return ROLLBACK;
         }
 
         @Override

community/kernel/src/main/java/org/neo4j/kernel/api/KernelTransaction.java

@@ -84,7 +84,8 @@ interface CloseListener
         void notify( boolean success );
     }
 
-    long NOT_COMMITTED = -1;
+    long ROLLBACK = -1;
+    long READ_ONLY = 0;
 
     /**
      * Acquires a new {@link Statement} for this transaction which allows for reading and writing data from and
@@ -108,16 +109,19 @@ interface CloseListener
     void failure();
 
     /**
-     * Closes this transaction, committing its changes iff {@link #success()} has been called and
-     * {@link #failure()} has NOT been called. Otherwise its changes will be rolled back.
+     * Closes this transaction, committing its changes if {@link #success()} has been called and neither
+     * {@link #failure()} nor {@link #markForTermination()} has been called.
+     * Otherwise its changes will be rolled back.
      *
-     * @return id of the committed transaction or {@link #NOT_COMMITTED} if transaction was rolled back or read-only.
+     * @return id of the committed transaction or {@link #ROLLBACK} if transaction was rolled back or
+     * {@link #READ_ONLY} if transaction was read-only.
      */
     long closeTransaction() throws TransactionFailureException;
 
     /**
-     * Closes this transaction, committing its changes iff {@link #success()} has been called and
-     * {@link #failure()} has NOT been called. Otherwise its changes will be rolled back.
+     * Closes this transaction, committing its changes if {@link #success()} has been called and neither
+     * {@link #failure()} nor {@link #markForTermination()} has been called.
+     * Otherwise its changes will be rolled back.
      */
     @Override
     default void close() throws TransactionFailureException

community/kernel/src/main/java/org/neo4j/kernel/impl/api/KernelTransactionImplementation.java

@@ -413,7 +413,7 @@ public long closeTransaction() throws TransactionFailureException
             {
                 rollback();
                 failOnNonExplicitRollbackIfNeeded();
-                return NOT_COMMITTED;
+                return ROLLBACK;
             }
             else
             {
@@ -538,7 +538,7 @@ private long commit() throws TransactionFailureException
                 }
             }
             success = true;
-            return NOT_COMMITTED;
+            return READ_ONLY;
         }
         catch ( ConstraintValidationKernelException | CreateConstraintFailureException e )
         {

community/kernel/src/test/java/org/neo4j/kernel/impl/api/constraints/ConstraintIndexCreatorTest.java

@@ -177,7 +177,7 @@ public void failure()
                 @Override
                 public long closeTransaction() throws TransactionFailureException
                 {
-                    return NOT_COMMITTED;
+                    return ROLLBACK;
                 }
 
                 @Override

community/kernel/src/test/java/org/neo4j/kernel/impl/api/integrationtest/KernelIT.java

@@ -553,7 +553,40 @@ public void txReturnsCorrectIdWhenRolledBack() throws Exception
         }
         tx.failure();
 
-        assertEquals( KernelTransaction.NOT_COMMITTED, tx.closeTransaction() );
+        assertEquals( KernelTransaction.ROLLBACK, tx.closeTransaction() );
+        assertFalse( tx.isOpen() );
+    }
+
+    @Test
+    public void txReturnsCorrectIdWhenMarkedForTermination() throws Exception
+    {
+        executeDummyTxs( db, 42 );
+
+        KernelTransaction tx = kernel.newTransaction( KernelTransaction.Type.implicit, AccessMode.Static.FULL );
+        try ( Statement statement = tx.acquireStatement() )
+        {
+            statement.dataWriteOperations().nodeCreate();
+        }
+        tx.markForTermination();
+
+        assertEquals( KernelTransaction.ROLLBACK, tx.closeTransaction() );
+        assertFalse( tx.isOpen() );
+    }
+
+    @Test
+    public void txReturnsCorrectIdWhenFailedlAndMarkedForTermination() throws Exception
+    {
+        executeDummyTxs( db, 42 );
+
+        KernelTransaction tx = kernel.newTransaction( KernelTransaction.Type.implicit, AccessMode.Static.FULL );
+        try ( Statement statement = tx.acquireStatement() )
+        {
+            statement.dataWriteOperations().nodeCreate();
+        }
+        tx.failure();
+        tx.markForTermination();
+
+        assertEquals( KernelTransaction.ROLLBACK, tx.closeTransaction() );
         assertFalse( tx.isOpen() );
     }
 
@@ -571,7 +604,7 @@ public void txReturnsCorrectIdWhenReadOnly() throws Exception
         }
         tx.success();
 
-        assertEquals( KernelTransaction.NOT_COMMITTED, tx.closeTransaction() );
+        assertEquals( KernelTransaction.READ_ONLY, tx.closeTransaction() );
         assertFalse( tx.isOpen() );
     }