#1245 - Refactor internals - Add to TransactionManager externalRemoveTransaction() and externalBeginTransaction()

These provide a better/tidier way for external transaction managers (like ebean-spring-txn) to begin and end externally
managed transactions.

src/main/java/io/ebeaninternal/api/SpiEbeanServer.java

@@ -80,6 +80,11 @@ public interface SpiEbeanServer extends EbeanServer, BeanLoader, BeanCollectionL
    */
   void clearQueryStatistics();
 
+  /**
+   * Return the transaction manager.
+   */
+  SpiTransactionManager getTransactionManager();
+
   /**
    * Return all the descriptors.
    */

src/main/java/io/ebeaninternal/api/SpiTransactionManager.java

@@ -0,0 +1,37 @@
+package io.ebeaninternal.api;
+
+import io.ebean.TxScope;
+
+import javax.sql.DataSource;
+
+/**
+ * Service provider interface for the transaction manager.
+ */
+public interface SpiTransactionManager {
+
+  /**
+   * Return the main DataSource.
+   */
+  DataSource getDataSource();
+
+  /**
+   * Return the read only DataSource (if defined).
+   */
+  DataSource getReadOnlyDataSource();
+
+  /**
+   * Return the currently active transaction (can be null).
+   */
+  SpiTransaction get();
+
+  /**
+   * Push an externally managed transaction into scope (e.g. Spring managed transaction).
+   */
+  ScopedTransaction externalBeginTransaction(SpiTransaction transaction, TxScope txScope);
+
+  /**
+   * Called when an externally managed transaction has completed.
+   */
+  void externalRemoveTransaction();
+
+}

src/main/java/io/ebeaninternal/server/core/DefaultServer.java

@@ -61,6 +61,7 @@ import io.ebeaninternal.api.SpiJsonContext;
 import io.ebeaninternal.api.SpiQuery;
 import io.ebeaninternal.api.SpiQuery.Type;
 import io.ebeaninternal.api.SpiTransaction;
+import io.ebeaninternal.api.SpiTransactionManager;
 import io.ebeaninternal.api.TransactionEventTable;
 import io.ebeaninternal.dbmigration.DdlGenerator;
 import io.ebeaninternal.dbmigration.ddlgeneration.DdlHandler;
@@ -1879,6 +1880,14 @@ public final class DefaultServer implements SpiServer, SpiEbeanServer {
     return beanDescriptorManager.getBeanDescriptorList();
   }
 
+  /**
+   * Return the transaction manager.
+   */
+  @Override
+  public SpiTransactionManager getTransactionManager() {
+    return transactionManager;
+  }
+
   public void register(BeanPersistController c) {
     List<BeanDescriptor<?>> list = beanDescriptorManager.getBeanDescriptorList();
     for (BeanDescriptor<?> aList : list) {

src/main/java/io/ebeaninternal/server/transaction/TransactionManager.java

@@ -16,6 +16,7 @@ import io.ebeaninternal.api.ScopeTrans;
 import io.ebeaninternal.api.ScopedTransaction;
 import io.ebeaninternal.api.SpiProfileHandler;
 import io.ebeaninternal.api.SpiTransaction;
+import io.ebeaninternal.api.SpiTransactionManager;
 import io.ebeaninternal.api.TransactionEvent;
 import io.ebeaninternal.api.TransactionEventTable;
 import io.ebeaninternal.api.TransactionEventTable.TableIUD;
@@ -46,7 +47,7 @@ import java.util.Set;
  * Keeps the Cache and Cluster in synch when transactions are committed.
  * </p>
  */
-public class TransactionManager {
+public class TransactionManager implements SpiTransactionManager {
 
   private static final Logger logger = LoggerFactory.getLogger(TransactionManager.class);
 
@@ -558,6 +559,23 @@ public class TransactionManager {
     }
   }
 
+  @Override
+  public void externalRemoveTransaction() {
+    scopeManager.replace(null);
+  }
+
+  /**
+   * Push an externally created transaction into scope. This transaction is usually managed externally
+   * (e.g. Spring managed transaction).
+   */
+  @Override
+  public ScopedTransaction externalBeginTransaction(SpiTransaction transaction, TxScope txScope) {
+    ScopedTransaction scopedTxn = new ScopedTransaction(scopeManager);
+    scopedTxn.push(new ScopeTrans(rollbackOnChecked, false, transaction, txScope));
+    scopeManager.set(scopedTxn);
+    return scopedTxn;
+  }
+
   /**
    * Begin a scoped transaction.
    */