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  package org.apache.cayenne.tx;
  
  import org.apache.cayenne.CayenneRuntimeException;
  import org.apache.cayenne.di.Inject;
  import org.apache.cayenne.log.JdbcEventLogger;
  
  /**
   * @since 4.0
   */
  public class DefaultTransactionManager implements TransactionManager {
  
      private TransactionFactory txFactory;
      private JdbcEventLogger jdbcEventLogger;
  
      public DefaultTransactionManager(@Inject TransactionFactory txFactory, @Inject JdbcEventLogger jdbcEventLogger) {
          this.txFactory = txFactory;
          this.jdbcEventLogger = jdbcEventLogger;
      }
  
      @Override
      public <T> T performInTransaction(TransactionalOperation<T> op) {
          return performInTransaction(op, DoNothingTransactionListener.getInstance(), TransactionDescriptor.defaultDescriptor());
      }
  
      @Override
      public <T> T performInTransaction(TransactionalOperation<T> op, TransactionListener callback) {
          return performInTransaction(op, callback, TransactionDescriptor.defaultDescriptor());
      }
  
      /**
       * @since 4.1
       */
      @Override
      public <T> T performInTransaction(TransactionalOperation<T> op, TransactionDescriptor descriptor) {
          return performInTransaction(op, DoNothingTransactionListener.getInstance(), descriptor);
      }
  
      /**
       * @since 4.1
       */
      @Override
      public <T> T performInTransaction(TransactionalOperation<T> op, TransactionListener callback, TransactionDescriptor descriptor) {
          BaseTransactionHandler handler = getHandler(descriptor);
          return handler.handle(op, callback, descriptor);
      }
  
      protected BaseTransactionHandler getHandler(TransactionDescriptor descriptor) {
          switch (descriptor.getPropagation()) {
              // MANDATORY requires transaction to exists
              case MANDATORY:
                  return new MandatoryTransactionHandler(txFactory, jdbcEventLogger);
  
              // NESTED can join existing or create new
              case NESTED:
                  return new NestedTransactionHandler(txFactory, jdbcEventLogger);
  
              // REQUIRES_NEW should always create new transaction
              case REQUIRES_NEW:
                  return new RequiresNewTransactionHandler(txFactory, jdbcEventLogger);
          }
  
          throw new CayenneRuntimeException("Unsupported transaction propagation: " + descriptor.getPropagation());
      }
  
      private static class NestedTransactionHandler extends BaseTransactionHandler {
  
          private NestedTransactionHandler(TransactionFactory txFactory, JdbcEventLogger jdbcEventLogger) {
              super(txFactory, jdbcEventLogger);
          }
  
          @Override
          protected <T> T handle(TransactionalOperation<T> op, TransactionListener callback, TransactionDescriptor descriptor) {
              Transaction currentTx = BaseTransaction.getThreadTransaction();
              if(currentTx != null) {
                  return performInTransaction(currentTx, op, callback);
              } else {
                  return performInNewTransaction(op, callback, descriptor);
              }
          }
      }
  
      private static class MandatoryTransactionHandler extends BaseTransactionHandler {
  
          private MandatoryTransactionHandler(TransactionFactory txFactory, JdbcEventLogger jdbcEventLogger) {
              super(txFactory, jdbcEventLogger);
          }
  
          @Override
          protected <T> T handle(TransactionalOperation<T> op, TransactionListener callback, TransactionDescriptor descriptor) {
              Transaction currentTx = BaseTransaction.getThreadTransaction();
              if(currentTx == null) {
                  throw new CayenneRuntimeException("Transaction operation should join to existing transaction but none found.");
              }
              return performInTransaction(currentTx, op, callback);
          }
      }
  
      private static class RequiresNewTransactionHandler extends BaseTransactionHandler {
  
          private RequiresNewTransactionHandler(TransactionFactory txFactory, JdbcEventLogger jdbcEventLogger) {
              super(txFactory, jdbcEventLogger);
          }
  
          @Override
          protected <T> T handle(TransactionalOperation<T> op, TransactionListener callback, TransactionDescriptor descriptor) {
              Transaction currentTx = BaseTransaction.getThreadTransaction();
              try {
                  return performInNewTransaction(op, callback, descriptor);
              } finally {
                  if(currentTx != null) {
                      // restore old transaction, if where set
                      BaseTransaction.bindThreadTransaction(currentTx);
                  }
              }
          }
      }
  
      protected static abstract class BaseTransactionHandler {
  
          private TransactionFactory txFactory;
          private JdbcEventLogger jdbcEventLogger;
  
          private BaseTransactionHandler(TransactionFactory txFactory, JdbcEventLogger jdbcEventLogger) {
              this.txFactory = txFactory;
              this.jdbcEventLogger = jdbcEventLogger;
          }
  
          protected abstract <T> T handle(TransactionalOperation<T> op, TransactionListener callback, TransactionDescriptor descriptor);
  
          protected <T> T performInNewTransaction(TransactionalOperation<T> op, TransactionListener callback, TransactionDescriptor descriptor) {
              Transaction tx = txFactory.createTransaction(descriptor);
              BaseTransaction.bindThreadTransaction(tx);
              try {
                  T result = performInTransaction(tx, op, callback);
                  tx.commit();
                  return result;
  
              } catch (CayenneRuntimeException ex) {
                  tx.setRollbackOnly();
                  throw ex;
              } catch (Exception ex) {
                  tx.setRollbackOnly();
                  throw new CayenneRuntimeException(ex);
              } finally {
                  BaseTransaction.bindThreadTransaction(null);
  
                  if (tx.isRollbackOnly()) {
                      try {
                          tx.rollback();
                      } catch (Exception e) {
                          // although we don't expect an exception here, print the
                          // stack, as there have been some Cayenne bugs already
                          // (CAY-557) that were masked by this 'catch' clause.
                          jdbcEventLogger.logQueryError(e);
                      }
                  }
              }
          }
  
          protected <T> T performInTransaction(Transaction tx, TransactionalOperation<T> op, TransactionListener callback) {
              tx.addListener(callback);
              return op.perform();
          }
  
      }
  
  }
  