/**
  * {@inheritDoc}
  */
 public function find($id, $lockMode = LockMode::NONE, $lockVersion = null)
 {
     // Check identity map first
     if ($entity = $this->_em->getUnitOfWork()->tryGetById($id, $this->_class->rootEntityName)) {
         if (!$entity instanceof $this->_class->name) {
             return null;
         }
         if ($lockMode != LockMode::NONE) {
             $this->_em->lock($entity, $lockMode, $lockVersion);
         }
         return $entity;
         // Hit!
     }
     if (!is_array($id) || count($id) <= 1) {
         // @todo FIXME: Not correct. Relies on specific order.
         $value = is_array($id) ? array_values($id) : array($id);
         $id = array_combine($this->_class->identifier, $value);
     }
     $id = $this->addInstanceFilter($id);
     if ($lockMode == LockMode::NONE) {
         return $this->_em->getUnitOfWork()->getEntityPersister($this->_entityName)->load($id);
     } else {
         if ($lockMode == LockMode::OPTIMISTIC) {
             if (!$this->_class->isVersioned) {
                 throw OptimisticLockException::notVersioned($this->_entityName);
             }
             $entity = $this->_em->getUnitOfWork()->getEntityPersister($this->_entityName)->load($id);
             $this->_em->getUnitOfWork()->lock($entity, $lockMode, $lockVersion);
             return $entity;
         } else {
             if (!$this->_em->getConnection()->isTransactionActive()) {
                 throw TransactionRequiredException::transactionRequired();
             }
             return $this->_em->getUnitOfWork()->getEntityPersister($this->_entityName)->load($id, null, null, array(), $lockMode);
         }
     }
 }

 /**
  * Set the lock mode for this Query.
  *
  * @see \Doctrine\DBAL\LockMode
  * @param  int $lockMode
  * @return Query
  */
 public function setLockMode($lockMode)
 {
     if (in_array($lockMode, array(LockMode::PESSIMISTIC_READ, LockMode::PESSIMISTIC_WRITE))) {
         if (!$this->_em->getConnection()->isTransactionActive()) {
             throw TransactionRequiredException::transactionRequired();
         }
     }
     $this->setHint(self::HINT_LOCK_MODE, $lockMode);
     return $this;
 }

 /**
  * Finds an Entity by its identifier.
  *
  * @param string       $entityName  The class name of the entity to find.
  * @param mixed        $id          The identity of the entity to find.
  * @param integer|null $lockMode    One of the \Doctrine\DBAL\LockMode::* constants
  *                                  or NULL if no specific lock mode should be used
  *                                  during the search.
  * @param integer|null $lockVersion The version of the entity to find when using
  *                                  optimistic locking.
  *
  * @return object|null The entity instance or NULL if the entity can not be found.
  *
  * @throws OptimisticLockException
  * @throws ORMInvalidArgumentException
  * @throws TransactionRequiredException
  * @throws ORMException
  */
 public function find($entityName, $id, $lockMode = null, $lockVersion = null)
 {
     $class = $this->metadataFactory->getMetadataFor(ltrim($entityName, '\\'));
     if (is_object($id) && $this->metadataFactory->hasMetadataFor(ClassUtils::getClass($id))) {
         $id = $this->unitOfWork->getSingleIdentifierValue($id);
         if ($id === null) {
             throw ORMInvalidArgumentException::invalidIdentifierBindingEntity();
         }
     }
     if (!is_array($id)) {
         $id = array($class->identifier[0] => $id);
     }
     $sortedId = array();
     foreach ($class->identifier as $identifier) {
         if (!isset($id[$identifier])) {
             throw ORMException::missingIdentifierField($class->name, $identifier);
         }
         $sortedId[$identifier] = $id[$identifier];
     }
     $unitOfWork = $this->getUnitOfWork();
     // Check identity map first
     if (($entity = $unitOfWork->tryGetById($sortedId, $class->rootEntityName)) !== false) {
         if (!$entity instanceof $class->name) {
             return null;
         }
         switch (true) {
             case LockMode::OPTIMISTIC === $lockMode:
                 $this->lock($entity, $lockMode, $lockVersion);
                 break;
             case LockMode::NONE === $lockMode:
             case LockMode::PESSIMISTIC_READ === $lockMode:
             case LockMode::PESSIMISTIC_WRITE === $lockMode:
                 $persister = $unitOfWork->getEntityPersister($class->name);
                 $persister->refresh($sortedId, $entity, $lockMode);
                 break;
         }
         return $entity;
         // Hit!
     }
     $persister = $unitOfWork->getEntityPersister($class->name);
     switch (true) {
         case LockMode::OPTIMISTIC === $lockMode:
             if (!$class->isVersioned) {
                 throw OptimisticLockException::notVersioned($class->name);
             }
             $entity = $persister->load($sortedId);
             $unitOfWork->lock($entity, $lockMode, $lockVersion);
             return $entity;
         case LockMode::NONE === $lockMode:
         case LockMode::PESSIMISTIC_READ === $lockMode:
         case LockMode::PESSIMISTIC_WRITE === $lockMode:
             if (!$this->getConnection()->isTransactionActive()) {
                 throw TransactionRequiredException::transactionRequired();
             }
             return $persister->load($sortedId, null, null, array(), $lockMode);
         default:
             return $persister->loadById($sortedId);
     }
 }

 /**
  * Acquire a lock on the given entity.
  *
  * @param object $entity
  * @param int    $lockMode
  * @param int    $lockVersion
  *
  * @return void
  *
  * @throws ORMInvalidArgumentException
  * @throws TransactionRequiredException
  * @throws OptimisticLockException
  */
 public function lock($entity, $lockMode, $lockVersion = null)
 {
     if ($entity === null) {
         throw new \InvalidArgumentException("No entity passed to UnitOfWork#lock().");
     }
     if ($this->getEntityState($entity, self::STATE_DETACHED) != self::STATE_MANAGED) {
         throw ORMInvalidArgumentException::entityNotManaged($entity);
     }
     $class = $this->em->getClassMetadata(get_class($entity));
     switch (true) {
         case LockMode::OPTIMISTIC === $lockMode:
             if (!$class->isVersioned) {
                 throw OptimisticLockException::notVersioned($class->name);
             }
             if ($lockVersion === null) {
                 return;
             }
             $entityVersion = $class->reflFields[$class->versionField]->getValue($entity);
             if ($entityVersion != $lockVersion) {
                 throw OptimisticLockException::lockFailedVersionMismatch($entity, $lockVersion, $entityVersion);
             }
             break;
         case LockMode::NONE === $lockMode:
         case LockMode::PESSIMISTIC_READ === $lockMode:
         case LockMode::PESSIMISTIC_WRITE === $lockMode:
             if (!$this->em->getConnection()->isTransactionActive()) {
                 throw TransactionRequiredException::transactionRequired();
             }
             $oid = spl_object_hash($entity);
             $this->getEntityPersister($class->name)->lock(array_combine($class->getIdentifierFieldNames(), $this->entityIdentifiers[$oid]), $lockMode);
             break;
         default:
             // Do nothing
     }
 }

 /**
  * Acquire a lock on the given entity.
  *
  * @param object $entity
  * @param int $lockMode
  * @param int $lockVersion
  */
 public function lock($entity, $lockMode, $lockVersion = null)
 {
     if ($this->getEntityState($entity) != self::STATE_MANAGED) {
         throw new InvalidArgumentException("Entity is not MANAGED.");
     }
     $entityName = get_class($entity);
     $class = $this->em->getClassMetadata($entityName);
     if ($lockMode == \Doctrine\DBAL\LockMode::OPTIMISTIC) {
         if (!$class->isVersioned) {
             throw OptimisticLockException::notVersioned($entityName);
         }
         if ($lockVersion != null) {
             $entityVersion = $class->reflFields[$class->versionField]->getValue($entity);
             if ($entityVersion != $lockVersion) {
                 throw OptimisticLockException::lockFailedVersionMissmatch($entity, $lockVersion, $entityVersion);
             }
         }
     } else {
         if (in_array($lockMode, array(\Doctrine\DBAL\LockMode::PESSIMISTIC_READ, \Doctrine\DBAL\LockMode::PESSIMISTIC_WRITE))) {
             if (!$this->em->getConnection()->isTransactionActive()) {
                 throw TransactionRequiredException::transactionRequired();
             }
             $oid = spl_object_hash($entity);
             $this->getEntityPersister($class->name)->lock(array_combine($class->getIdentifierFieldNames(), $this->entityIdentifiers[$oid]), $lockMode);
         }
     }
 }

 /**
  * Finds an entity by its primary key / identifier.
  *
  * @param $id The identifier.
  * @param int $lockMode
  * @param int $lockVersion
  * @return object The entity.
  */
 public function find($id, $lockMode = LockMode::NONE, $lockVersion = null)
 {
     if (!is_array($id)) {
         $id = array($this->_class->identifier[0] => $id);
     }
     $sortedId = array();
     foreach ($this->_class->identifier as $identifier) {
         if (!isset($id[$identifier])) {
             throw ORMException::missingIdentifierField($this->_class->name, $identifier);
         }
         $sortedId[$identifier] = $id[$identifier];
     }
     // Check identity map first
     if (($entity = $this->_em->getUnitOfWork()->tryGetById($sortedId, $this->_class->rootEntityName)) !== false) {
         if (!$entity instanceof $this->_class->name) {
             return null;
         }
         if ($lockMode !== LockMode::NONE) {
             $this->_em->lock($entity, $lockMode, $lockVersion);
         }
         return $entity;
         // Hit!
     }
     $persister = $this->_em->getUnitOfWork()->getEntityPersister($this->_entityName);
     switch ($lockMode) {
         case LockMode::NONE:
             return $persister->load($sortedId);
         case LockMode::OPTIMISTIC:
             if (!$this->_class->isVersioned) {
                 throw OptimisticLockException::notVersioned($this->_entityName);
             }
             $entity = $persister->load($sortedId);
             $this->_em->getUnitOfWork()->lock($entity, $lockMode, $lockVersion);
             return $entity;
         default:
             if (!$this->_em->getConnection()->isTransactionActive()) {
                 throw TransactionRequiredException::transactionRequired();
             }
             return $persister->load($sortedId, null, null, array(), $lockMode);
     }
 }