com.google.inject.persist.UnitOfWork Maven / Gradle / Ivy
/*
* 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.
*
* 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).
*
*
* - Using UnitOfWork with the PersistFilter inside a request is not recommended.
*
- Using UnitOfWork with session-per-txn strategy is not terribly clever either.
*
- 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.
*
*
* @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.
*
*
Transaction semantics are not affected.
*/
void end();
}