# UnitOfWorkTemplate.java

    /*
     * Licensed to the Apache Software Foundation (ASF) under one
     * or more contributor license agreements.  See the NOTICE file
     * distributed with this work for additional information
     * regarding copyright ownership.  The ASF licenses this file
     * to you under the Apache License, Version 2.0 (the
     * "License"); you may not use this file except in compliance
     * with the License.  You may obtain a copy of the License at
     *
     *   http://www.apache.org/licenses/LICENSE-2.0
     *
     * Unless required by applicable law or agreed to in writing,
     * software distributed under the License is distributed on an
     * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
     * KIND, either express or implied.  See the License for the
     * specific language governing permissions and limitations
     * under the License.
     */
    package org.qi4j.api.unitofwork;

    import org.qi4j.api.structure.Module;
    import org.qi4j.api.usecase.Usecase;

    /**
     * UnitOfWork Template.
     */
    public abstract class UnitOfWorkTemplate<RESULT, ThrowableType extends Throwable>
    {
        private Usecase usecase = Usecase.DEFAULT;
        private int retries = 10;
        private boolean complete = true;

        protected UnitOfWorkTemplate()
        {
        }

        protected UnitOfWorkTemplate( int retries, boolean complete )
        {
            this.retries = retries;
            this.complete = complete;
        }

        protected UnitOfWorkTemplate( Usecase usecase, int retries, boolean complete )
        {
            this.usecase = usecase;
            this.retries = retries;
            this.complete = complete;
        }

        protected abstract RESULT withUnitOfWork( UnitOfWork uow )
            throws ThrowableType;

        @SuppressWarnings( "unchecked" )
        public RESULT withModule( Module module )
            throws ThrowableType, UnitOfWorkCompletionException
        {
            int loop = 0;
            ThrowableType ex = null;
            do
            {
                UnitOfWork uow = module.newUnitOfWork( usecase );

                try
                {
                    RESULT result = withUnitOfWork( uow );
                    if( complete )
                    {
                        try
                        {
                            uow.complete();
                            return result;
                        }
                        catch( ConcurrentEntityModificationException e )
                        {
                            // Retry?
                            ex = (ThrowableType) e;
                        }
                    }
                }
                catch( Throwable e )
                {
                    ex = (ThrowableType) e;
                }
                finally
                {
                    uow.discard();
                }
            }
            while( loop++ < retries );

            throw ex;
        }
    }