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/***
*
* Copyright 2014 Andrew Hall
*
* 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 org.statefulj.persistence.jpa;
import java.lang.reflect.Field;
import java.util.List;
import javax.persistence.EmbeddedId;
import javax.persistence.EntityManager;
import javax.persistence.Id;
import javax.persistence.NoResultException;
import javax.persistence.Query;
import javax.persistence.criteria.CriteriaBuilder;
import javax.persistence.criteria.CriteriaQuery;
import javax.persistence.criteria.CriteriaUpdate;
import javax.persistence.criteria.Path;
import javax.persistence.criteria.Predicate;
import javax.persistence.criteria.Root;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.orm.jpa.EntityManagerFactoryInfo;
import org.springframework.transaction.annotation.Transactional;
import org.statefulj.fsm.Persister;
import org.statefulj.fsm.StaleStateException;
import org.statefulj.fsm.model.State;
import org.statefulj.persistence.common.AbstractPersister;
import static org.statefulj.common.utils.ReflectionUtils.*;
@Transactional
public class JPAPerister extends AbstractPersister implements Persister {
private static final Logger logger = LoggerFactory.getLogger(JPAPerister.class);
private EntityManager entityManager;
public JPAPerister(List> states, State start, Class clazz, EntityManagerFactoryInfo entityManagerFactory) {
this(states, null, start, clazz, entityManagerFactory.getNativeEntityManagerFactory().createEntityManager());
}
public JPAPerister(List> states, String stateFieldName, State start, Class clazz, EntityManager entityManager) {
super(states, stateFieldName, start, clazz);
this.entityManager = entityManager;
}
/**
* Set the current State. This method will ensure that the state in the db matches the expected current state.
* If not, it will throw a StateStateException
*
* @param stateful Stateful Entity
* @param current Expected current State
* @param next The value of the next State
* @throws StaleStateException thrown if the value of the State does not equal to the provided current State
*/
@Override
public void setCurrent(T stateful, State current, State next) throws StaleStateException {
try {
// Has this Entity been persisted to the database?
//
Object id = getId(stateful);
if (id != null && entityManager.contains(stateful)) {
updateStateInDB(stateful, current, next, id);
setState(stateful, next.getName());
} else {
updateStateInMemory(stateful, current, next);
}
} catch (NoSuchFieldException e) {
throw new RuntimeException(e);
} catch (SecurityException e) {
throw new RuntimeException(e);
} catch (IllegalArgumentException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
}
}
/**
* @param stateful
* @param current
* @param next
* @throws NoSuchFieldException
* @throws IllegalAccessException
* @throws StaleStateException
*/
private void updateStateInMemory(T stateful, State current, State next)
throws NoSuchFieldException, IllegalAccessException,
StaleStateException {
// The Entity hasn't been persisted to the database - so it exists only
// this Application memory. So, serialize the qualified update to prevent
// concurrency conflicts
//
synchronized(stateful) {
String state = this.getState(stateful);
state = (state == null) ? getStart().getName() : state;
if (state.equals(current.getName())) {
setState(stateful, next.getName());
} else {
throwStaleState(current, next);
}
}
}
/**
* @param stateful
* @param current
* @param next
* @param id
* @throws NoSuchFieldException
* @throws IllegalAccessException
* @throws StaleStateException
*/
private void updateStateInDB(T stateful, State current, State next,
Object id) throws NoSuchFieldException, IllegalAccessException,
StaleStateException {
// Entity is in the database - perform qualified update based off
// the current State value
//
Query update = buildUpdate(id, stateful, current, next, getIdField(), getStateField());
// Successful update?
//
if (update.executeUpdate() == 0) {
// If we aren't able to update - it's most likely that we are out of sync.
// So, fetch the latest value and update the Stateful object. Then throw a RetryException
// This will cause the event to be reprocessed by the FSM
//
Query query = buildQuery(id, stateful);
String state = getStart().getName();
try {
state = (String)query.getSingleResult();
} catch(NoResultException nre) {
// This is the first time setting the state, ignore
//
}
logger.warn("Stale State, expected={}, actual={}", current.getName(), state);
setState(stateful, state);
throwStaleState(current, next);
}
}
protected Query buildUpdate(
Object id,
T stateful,
State current,
State next,
Field idField,
Field stateField) throws SecurityException, IllegalArgumentException, NoSuchFieldException, IllegalAccessException {
CriteriaBuilder cb = this.entityManager.getCriteriaBuilder();
// update
//
CriteriaUpdate cu = cb.createCriteriaUpdate(this.getClazz());
Root t = cu.from(this.getClazz());
Path idPath = t.get(this.getIdField().getName());
Path statePath = t.get(this.getStateField().getName());
// set state=
//
cu.set(statePath, next.getName());
// where id= and state=
//
Predicate statePredicate = (current.equals(getStart())) ?
cb.or(
cb.equal(
statePath,
current.getName()
),
cb.equal(
statePath,
cb.nullLiteral(String.class)
)
) :
cb.equal(
statePath,
current.getName()
);
cu.where(
cb.and(
cb.equal(
idPath,
this.getId(stateful)
),
statePredicate
)
);
Query query = entityManager.createQuery(cu);
if (logger.isDebugEnabled()) {
logger.debug(query.unwrap(org.hibernate.Query.class).getQueryString());
}
return query;
}
@Override
protected boolean validStateField(Field stateField) {
return (stateField.getType().equals(String.class));
}
@Override
protected Field findIdField(Class clazz) {
Field idField = null;
idField = getReferencedField(clazz, Id.class);
if (idField == null) {
idField = getReferencedField(clazz, EmbeddedId.class);
}
return idField;
}
@Override
protected Class getStateFieldType() {
return String.class;
}
private Query buildQuery(Object id, T stateful) throws SecurityException, IllegalArgumentException, NoSuchFieldException, IllegalAccessException {
CriteriaBuilder cb = this.entityManager.getCriteriaBuilder();
CriteriaQuery cq = cb.createQuery(String.class);
Root t = cq.from(this.getClazz());
Path idPath = t.get(this.getIdField().getName());
Path statePath = t.get(this.getStateField().getName());
cq.select(statePath);
cq.where(cb.equal(idPath, this.getId(stateful)));
Query query = entityManager.createQuery(cq);
if (logger.isDebugEnabled()) {
logger.debug(query.unwrap(org.hibernate.Query.class).getQueryString());
}
return query;
}
}
