Added explicit UoW to the EventTriggerCallback

This improves the lock release timing when using transactions. It ensures that locks are only released when all of the underlying transactions are committed.
(cherry picked from commit 27413b1)

core/src/main/java/org/axonframework/eventhandling/scheduling/SpringTransactionalTriggerCallback.java

@@ -31,38 +31,28 @@
  * @author Allard Buijze
  * @since 1.1
  */
-public class SpringTransactionalTriggerCallback implements EventTriggerCallback, InitializingBean {
+public class SpringTransactionalTriggerCallback extends TransactionalEventTriggerCallback<TransactionStatus>
+        implements InitializingBean {
 
-    private final ThreadLocal<TransactionStatus> transactions = new ThreadLocal<TransactionStatus>();
     private PlatformTransactionManager transactionManager;
     private TransactionDefinition transactionDefinition = new DefaultTransactionDefinition();
 
     @Override
-    public void beforePublication(ApplicationEvent event) {
-        transactions.set(transactionManager.getTransaction(transactionDefinition));
+    protected TransactionStatus startUnderlyingTransaction(ApplicationEvent event) {
+        return transactionManager.getTransaction(transactionDefinition);
     }
 
     @Override
-    public void afterPublicationSuccess() {
-        try {
-            TransactionStatus status = transactions.get();
-            if (status.isNewTransaction()) {
-                transactionManager.commit(status);
-            }
-        } finally {
-            transactions.remove();
+    protected void commitUnderlyingTransaction(TransactionStatus tx) {
+        if (tx.isNewTransaction()) {
+            transactionManager.commit(tx);
         }
     }
 
     @Override
-    public void afterPublicationFailure(RuntimeException cause) {
-        try {
-            TransactionStatus status = transactions.get();
-            if (status.isNewTransaction() && !status.isCompleted()) {
-                transactionManager.rollback(status);
-            }
-        } finally {
-            transactions.remove();
+    protected void rollbackUnderlyingTransaction(TransactionStatus tx) {
+        if (tx.isNewTransaction() && !tx.isCompleted()) {
+            transactionManager.rollback(tx);
         }
     }
 

core/src/main/java/org/axonframework/eventhandling/scheduling/TransactionalEventTriggerCallback.java

@@ -0,0 +1,74 @@
+package org.axonframework.eventhandling.scheduling;
+
+import org.axonframework.domain.ApplicationEvent;
+import org.axonframework.unitofwork.CurrentUnitOfWork;
+import org.axonframework.unitofwork.DefaultUnitOfWork;
+import org.axonframework.unitofwork.UnitOfWork;
+import org.axonframework.unitofwork.UnitOfWorkListenerAdapter;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Abstract implementation of the {@link EventTriggerCallback} interface that ensures a UnitOfWork is used to contain
+ * the transaction. This way, proper locking and unlocking ordering is guaranteed in combination with the underlying
+ * transaction.
+ *
+ * @param <T> The type of transaction status object used by the backing transaction manager
+ * @author Allard Buijze
+ * @since 1.3
+ */
+public abstract class TransactionalEventTriggerCallback<T> implements EventTriggerCallback {
+
+    private static final Logger logger = LoggerFactory.getLogger(TransactionalEventTriggerCallback.class);
+
+    @Override
+    public void beforePublication(ApplicationEvent event) {
+        UnitOfWork uow = DefaultUnitOfWork.startAndGet();
+        final T tx = startUnderlyingTransaction(event);
+        uow.registerListener(new UnitOfWorkListenerAdapter() {
+            @Override
+            public void onRollback(Throwable failureCause) {
+                logger.warn("Rolling back transaction due to exception.", failureCause);
+                rollbackUnderlyingTransaction(tx);
+            }
+
+            @Override
+            public void afterCommit() {
+                commitUnderlyingTransaction(tx);
+            }
+        });
+    }
+
+    @Override
+    public void afterPublicationSuccess() {
+        CurrentUnitOfWork.commit();
+    }
+
+    @Override
+    public void afterPublicationFailure(RuntimeException cause) {
+        CurrentUnitOfWork.get().rollback(cause);
+    }
+
+    /**
+     * Starts a transaction in the underlying transaction manager. The returned value will be passed as parameter to
+     * the {@link #commitUnderlyingTransaction(Object)} or {@link #rollbackUnderlyingTransaction(Object)} method.
+     *
+     * @param event the event for which a transaction should be started
+     * @return an object describing the underlying transaction.
+     */
+    protected abstract T startUnderlyingTransaction(ApplicationEvent event);
+
+    /**
+     * Commits the transaction described by <code>tx</code> in the underlying transaction manager.
+     *
+     * @param tx The object returned by {@link #startUnderlyingTransaction(org.axonframework.domain.ApplicationEvent)}
+     */
+    protected abstract void commitUnderlyingTransaction(T tx);
+
+    /**
+     * Rolls back the transaction described by <code>tx</code> in the underlying transaction manager.
+     *
+     * @param tx The object returned by {@link #startUnderlyingTransaction(org.axonframework.domain.ApplicationEvent)}
+     */
+    protected abstract void rollbackUnderlyingTransaction(T tx);
+}