| /** |
| * Copyright (C) 2010 Google, Inc. |
| * |
| * Licensed 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 com.google.inject.persist; |
| |
| /** |
| * This interface is used to gain manual control over the unit of work. This is mostly to do |
| * work in non-request, non-transactional threads. Or where more fine-grained control over the unit |
| * of work is required. Starting and ending a unit of work directly corresponds to opening and |
| * closing a {@code Session}, {@code EntityManager} or {@code ObjectContainer} respectively. |
| * <p> The |
| * Unit of Work referred to by UnitOfWork will always be local to the calling thread. Be careful to |
| * end() in a finally block. Neither JPA, nor Hibernate supports threadsafe sessions (reasoning |
| * behind thread-locality of Unit of Work semantics). |
| * |
| * <ul> |
| * <li>Using UnitOfWork with the PersistFilter inside a request is not recommended.</li> |
| * <li>Using UnitOfWork with session-per-txn strategy is not terribly clever either.</li> |
| * <li>Using UnitOfWork with session-per-request strategy but *outside* a request (i.e. in a |
| * background or bootstrap thread) is probably a good use case.</li> |
| * </ul> |
| * |
| * @author Dhanji R. Prasanna (dhanji@gmail com) |
| */ |
| public interface UnitOfWork { |
| |
| /** |
| * Starts a Unit Of Work. Underneath, causes a session to the data layer to be opened. If there |
| * is already one open, the invocation will do nothing. In this way, you can define arbitrary |
| * units-of-work that nest within one another safely. |
| * |
| * Transaction semantics are not affected. |
| */ |
| void begin(); |
| |
| /** |
| * Declares an end to the current Unit of Work. Underneath, causes any open session to the data |
| * layer to close. If there is no Unit of work open, then the call returns silently. You can |
| * safely invoke end() repeatedly. |
| * <p> |
| * Transaction semantics are not affected. |
| */ |
| void end(); |
| } |