/lib/Doctrine/ORM/UnitOfWork.php

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<?php
/*
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * This software consists of voluntary contributions made by many individuals
 * and is licensed under the MIT license. For more information, see
 * <http://www.doctrine-project.org>.
 */

namespace Doctrine\ORM;

use Exception;
use InvalidArgumentException;
use UnexpectedValueException;
use Doctrine\Common\Collections\ArrayCollection;
use Doctrine\Common\Collections\Collection;
use Doctrine\Common\NotifyPropertyChanged;
use Doctrine\Common\PropertyChangedListener;
use Doctrine\Common\Persistence\ObjectManagerAware;
use Doctrine\ORM\Event\LifecycleEventArgs;
use Doctrine\ORM\Mapping\ClassMetadata;
use Doctrine\ORM\Proxy\Proxy;

/**
 * The UnitOfWork is responsible for tracking changes to objects during an
 * "object-level" transaction and for writing out changes to the database
 * in the correct order.
 *
 * @since       2.0
 * @author      Benjamin Eberlei <kontakt@beberlei.de>
 * @author      Guilherme Blanco <guilhermeblanco@hotmail.com>
 * @author      Jonathan Wage <jonwage@gmail.com>
 * @author      Roman Borschel <roman@code-factory.org>
 * @internal    This class contains highly performance-sensitive code.
 */
class UnitOfWork implements PropertyChangedListener
{
    /**
     * An entity is in MANAGED state when its persistence is managed by an EntityManager.
     */
    const STATE_MANAGED = 1;

    /**
     * An entity is new if it has just been instantiated (i.e. using the "new" operator)
     * and is not (yet) managed by an EntityManager.
     */
    const STATE_NEW = 2;

    /**
     * A detached entity is an instance with persistent state and identity that is not
     * (or no longer) associated with an EntityManager (and a UnitOfWork).
     */
    const STATE_DETACHED = 3;

    /**
     * A removed entity instance is an instance with a persistent identity,
     * associated with an EntityManager, whose persistent state will be deleted
     * on commit.
     */
    const STATE_REMOVED = 4;

    /**
     * The identity map that holds references to all managed entities that have
     * an identity. The entities are grouped by their class name.
     * Since all classes in a hierarchy must share the same identifier set,
     * we always take the root class name of the hierarchy.
     *
     * @var array
     */
    private $identityMap = array();

    /**
     * Map of all identifiers of managed entities.
     * Keys are object ids (spl_object_hash).
     *
     * @var array
     */
    private $entityIdentifiers = array();

    /**
     * Map of the original entity data of managed entities.
     * Keys are object ids (spl_object_hash). This is used for calculating changesets
     * at commit time.
     *
     * @var array
     * @internal Note that PHPs "copy-on-write" behavior helps a lot with memory usage.
     *           A value will only really be copied if the value in the entity is modified
     *           by the user.
     */
    private $originalEntityData = array();

    /**
     * Map of entity changes. Keys are object ids (spl_object_hash).
     * Filled at the beginning of a commit of the UnitOfWork and cleaned at the end.
     *
     * @var array
     */
    private $entityChangeSets = array();

    /**
     * The (cached) states of any known entities.
     * Keys are object ids (spl_object_hash).
     *
     * @var array
     */
    private $entityStates = array();

    /**
     * Map of entities that are scheduled for dirty checking at commit time.
     * This is only used for entities with a change tracking policy of DEFERRED_EXPLICIT.
     * Keys are object ids (spl_object_hash).
     *
     * @var array
     * @todo rename: scheduledForSynchronization
     */
    private $scheduledForDirtyCheck = array();

    /**
     * A list of all pending entity insertions.
     *
     * @var array
     */
    private $entityInsertions = array();

    /**
     * A list of all pending entity updates.
     *
     * @var array
     */
    private $entityUpdates = array();

    /**
     * Any pending extra updates that have been scheduled by persisters.
     *
     * @var array
     */
    private $extraUpdates = array();

    /**
     * A list of all pending entity deletions.
     *
     * @var array
     */
    private $entityDeletions = array();

    /**
     * All pending collection deletions.
     *
     * @var array
     */
    private $collectionDeletions = array();

    /**
     * All pending collection updates.
     *
     * @var array
     */
    private $collectionUpdates = array();

    /**
     * List of collections visited during changeset calculation on a commit-phase of a UnitOfWork.
     * At the end of the UnitOfWork all these collections will make new snapshots
     * of their data.
     *
     * @var array
     */
    private $visitedCollections = array();

    /**
     * The EntityManager that "owns" this UnitOfWork instance.
     *
     * @var \Doctrine\ORM\EntityManager
     */
    private $em;

    /**
     * The calculator used to calculate the order in which changes to
     * entities need to be written to the database.
     *
     * @var \Doctrine\ORM\Internal\CommitOrderCalculator
     */
    private $commitOrderCalculator;

    /**
     * The entity persister instances used to persist entity instances.
     *
     * @var array
     */
    private $persisters = array();

    /**
     * The collection persister instances used to persist collections.
     *
     * @var array
     */
    private $collectionPersisters = array();

    /**
     * The EventManager used for dispatching events.
     *
     * @var \Doctrine\Common\EventManager
     */
    private $evm;

    /**
     * Orphaned entities that are scheduled for removal.
     *
     * @var array
     */
    private $orphanRemovals = array();

    /**
     * Read-Only objects are never evaluated
     *
     * @var array
     */
    private $readOnlyObjects = array();

    /**
     * Map of Entity Class-Names and corresponding IDs that should eager loaded when requested.
     *
     * @var array
     */
    private $eagerLoadingEntities = array();

    /**
     * Initializes a new UnitOfWork instance, bound to the given EntityManager.
     *
     * @param \Doctrine\ORM\EntityManager $em
     */
    public function __construct(EntityManager $em)
    {
        $this->em = $em;
        $this->evm = $em->getEventManager();
    }

    /**
     * Commits the UnitOfWork, executing all operations that have been postponed
     * up to this point. The state of all managed entities will be synchronized with
     * the database.
     *
     * The operations are executed in the following order:
     *
     * 1) All entity insertions
     * 2) All entity updates
     * 3) All collection deletions
     * 4) All collection updates
     * 5) All entity deletions
     *
     * @param null|object|array $entity
     *
     * @throws \Exception
     *
     * @return void
     */
    public function commit($entity = null)
    {
        // Raise preFlush
        if ($this->evm->hasListeners(Events::preFlush)) {
            $this->evm->dispatchEvent(Events::preFlush, new Event\PreFlushEventArgs($this->em));
        }

        // Compute changes done since last commit.
        if ($entity === null) {
            $this->computeChangeSets();
        } elseif (is_object($entity)) {
            $this->computeSingleEntityChangeSet($entity);
        } elseif (is_array($entity)) {
            foreach ($entity as $object) {
                $this->computeSingleEntityChangeSet($object);
            }
        }

        if ( ! ($this->entityInsertions ||
                $this->entityDeletions ||
                $this->entityUpdates ||
                $this->collectionUpdates ||
                $this->collectionDeletions ||
                $this->orphanRemovals)) {
            return; // Nothing to do.
        }

        if ($this->orphanRemovals) {
            foreach ($this->orphanRemovals as $orphan) {
                $this->remove($orphan);
            }
        }

        // Raise onFlush
        if ($this->evm->hasListeners(Events::onFlush)) {
            $this->evm->dispatchEvent(Events::onFlush, new Event\OnFlushEventArgs($this->em));
        }

        // Now we need a commit order to maintain referential integrity
        $commitOrder = $this->getCommitOrder();

        $conn = $this->em->getConnection();
        $conn->beginTransaction();

        try {
            if ($this->entityInsertions) {
                foreach ($commitOrder as $class) {
                    $this->executeInserts($class);
                }
            }

            if ($this->entityUpdates) {
                foreach ($commitOrder as $class) {
                    $this->executeUpdates($class);
                }
            }

            // Extra updates that were requested by persisters.
            if ($this->extraUpdates) {
                $this->executeExtraUpdates();
            }

            // Collection deletions (deletions of complete collections)
            foreach ($this->collectionDeletions as $collectionToDelete) {
                $this->getCollectionPersister($collectionToDelete->getMapping())->delete($collectionToDelete);
            }
            // Collection updates (deleteRows, updateRows, insertRows)
            foreach ($this->collectionUpdates as $collectionToUpdate) {
                $this->getCollectionPersister($collectionToUpdate->getMapping())->update($collectionToUpdate);
            }

            // Entity deletions come last and need to be in reverse commit order
            if ($this->entityDeletions) {
                for ($count = count($commitOrder), $i = $count - 1; $i >= 0; --$i) {
                    $this->executeDeletions($commitOrder[$i]);
                }
            }

            $conn->commit();
        } catch (Exception $e) {
            $this->em->close();
            $conn->rollback();

            throw $e;
        }

        // Take new snapshots from visited collections
        foreach ($this->visitedCollections as $coll) {
            $coll->takeSnapshot();
        }

        // Raise postFlush
        if ($this->evm->hasListeners(Events::postFlush)) {
            $this->evm->dispatchEvent(Events::postFlush, new Event\PostFlushEventArgs($this->em));
        }

        // Clear up
        $this->entityInsertions =
        $this->entityUpdates =
        $this->entityDeletions =
        $this->extraUpdates =
        $this->entityChangeSets =
        $this->collectionUpdates =
        $this->collectionDeletions =
        $this->visitedCollections =
        $this->scheduledForDirtyCheck =
        $this->orphanRemovals = array();
    }

    /**
     * Compute the changesets of all entities scheduled for insertion
     *
     * @return void
     */
    private function computeScheduleInsertsChangeSets()
    {
        foreach ($this->entityInsertions as $entity) {
            $class = $this->em->getClassMetadata(get_class($entity));

            $this->computeChangeSet($class, $entity);
        }
    }

    /**
     * Only flush the given entity according to a ruleset that keeps the UoW consistent.
     *
     * 1. All entities scheduled for insertion, (orphan) removals and changes in collections are processed as well!
     * 2. Read Only entities are skipped.
     * 3. Proxies are skipped.
     * 4. Only if entity is properly managed.
     *
     * @param  object $entity
     *
     * @throws \InvalidArgumentException
     *
     * @return void
     */
    private function computeSingleEntityChangeSet($entity)
    {
        if ( $this->getEntityState($entity) !== self::STATE_MANAGED) {
            throw new \InvalidArgumentException("Entity has to be managed for single computation " . self::objToStr($entity));
        }

        $class = $this->em->getClassMetadata(get_class($entity));

        if ($class->isChangeTrackingDeferredImplicit()) {
            $this->persist($entity);
        }

        // Compute changes for INSERTed entities first. This must always happen even in this case.
        $this->computeScheduleInsertsChangeSets();

        if ($class->isReadOnly) {
            return;
        }

        // Ignore uninitialized proxy objects
        if ($entity instanceof Proxy && ! $entity->__isInitialized__) {
            return;
        }

        // Only MANAGED entities that are NOT SCHEDULED FOR INSERTION are processed here.
        $oid = spl_object_hash($entity);

        if ( ! isset($this->entityInsertions[$oid]) && isset($this->entityStates[$oid])) {
            $this->computeChangeSet($class, $entity);
        }
    }

    /**
     * Executes any extra updates that have been scheduled.
     */
    private function executeExtraUpdates()
    {
        foreach ($this->extraUpdates as $oid => $update) {
            list ($entity, $changeset) = $update;

            $this->entityChangeSets[$oid] = $changeset;
            $this->getEntityPersister(get_class($entity))->update($entity);
        }
    }

    /**
     * Gets the changeset for an entity.
     *
     * @param object $entity
     *
     * @return array
     */
    public function getEntityChangeSet($entity)
    {
        $oid = spl_object_hash($entity);

        if (isset($this->entityChangeSets[$oid])) {
            return $this->entityChangeSets[$oid];
        }

        return array();
    }

    /**
     * Computes the changes that happened to a single entity.
     *
     * Modifies/populates the following properties:
     *
     * {@link _originalEntityData}
     * If the entity is NEW or MANAGED but not yet fully persisted (only has an id)
     * then it was not fetched from the database and therefore we have no original
     * entity data yet. All of the current entity data is stored as the original entity data.
     *
     * {@link _entityChangeSets}
     * The changes detected on all properties of the entity are stored there.
     * A change is a tuple array where the first entry is the old value and the second
     * entry is the new value of the property. Changesets are used by persisters
     * to INSERT/UPDATE the persistent entity state.
     *
     * {@link _entityUpdates}
     * If the entity is already fully MANAGED (has been fetched from the database before)
     * and any changes to its properties are detected, then a reference to the entity is stored
     * there to mark it for an update.
     *
     * {@link _collectionDeletions}
     * If a PersistentCollection has been de-referenced in a fully MANAGED entity,
     * then this collection is marked for deletion.
     *
     * @ignore
     * @internal Don't call from the outside.
     * @param ClassMetadata $class The class descriptor of the entity.
     * @param object $entity The entity for which to compute the changes.
     */
    public function computeChangeSet(ClassMetadata $class, $entity)
    {
        $oid = spl_object_hash($entity);

        if (isset($this->readOnlyObjects[$oid])) {
            return;
        }

        if ( ! $class->isInheritanceTypeNone()) {
            $class = $this->em->getClassMetadata(get_class($entity));
        }

        // Fire PreFlush lifecycle callbacks
        if (isset($class->lifecycleCallbacks[Events::preFlush])) {
            $class->invokeLifecycleCallbacks(Events::preFlush, $entity);
        }

        $actualData = array();

        foreach ($class->reflFields as $name => $refProp) {
            $value = $refProp->getValue($entity);

            if ($class->isCollectionValuedAssociation($name) && $value !== null && ! ($value instanceof PersistentCollection)) {
                // If $value is not a Collection then use an ArrayCollection.
                if ( ! $value instanceof Collection) {
                    $value = new ArrayCollection($value);
                }

                $assoc = $class->associationMappings[$name];

                // Inject PersistentCollection
                $value = new PersistentCollection(
                    $this->em, $this->em->getClassMetadata($assoc['targetEntity']), $value
                );
                $value->setOwner($entity, $assoc);
                $value->setDirty( ! $value->isEmpty());

                $class->reflFields[$name]->setValue($entity, $value);

                $actualData[$name] = $value;

                continue;
            }

            if (( ! $class->isIdentifier($name) || ! $class->isIdGeneratorIdentity()) && ($name !== $class->versionField)) {
                $actualData[$name] = $value;
            }
        }

        if ( ! isset($this->originalEntityData[$oid])) {
            // Entity is either NEW or MANAGED but not yet fully persisted (only has an id).
            // These result in an INSERT.
            $this->originalEntityData[$oid] = $actualData;
            $changeSet = array();

            foreach ($actualData as $propName => $actualValue) {
                if ( ! isset($class->associationMappings[$propName])) {
                    $changeSet[$propName] = array(null, $actualValue);

                    continue;
                }

                $assoc = $class->associationMappings[$propName];

                if ($assoc['isOwningSide'] && $assoc['type'] & ClassMetadata::TO_ONE) {
                    $changeSet[$propName] = array(null, $actualValue);
                }
            }

            $this->entityChangeSets[$oid] = $changeSet;
        } else {
            // Entity is "fully" MANAGED: it was already fully persisted before
            // and we have a copy of the original data
            $originalData           = $this->originalEntityData[$oid];
            $isChangeTrackingNotify = $class->isChangeTrackingNotify();
            $changeSet              = ($isChangeTrackingNotify && isset($this->entityChangeSets[$oid]))
                ? $this->entityChangeSets[$oid]
                : array();

            foreach ($actualData as $propName => $actualValue) {
                // skip field, its a partially omitted one!
                if ( ! (isset($originalData[$propName]) || array_key_exists($propName, $originalData))) {
                    continue;
                }

                $orgValue = $originalData[$propName];

                // skip if value havent changed
                if ($orgValue === $actualValue) {
                    continue;
                }

                // if regular field
                if ( ! isset($class->associationMappings[$propName])) {
                    if ($isChangeTrackingNotify) {
                        continue;
                    }

                    $changeSet[$propName] = array($orgValue, $actualValue);

                    continue;
                }

                $assoc = $class->associationMappings[$propName];

                // Persistent collection was exchanged with the "originally"
                // created one. This can only mean it was cloned and replaced
                // on another entity.
                if ($actualValue instanceof PersistentCollection) {
                    $owner = $actualValue->getOwner();
                    if ($owner === null) { // cloned
                        $actualValue->setOwner($entity, $assoc);
                    } else if ($owner !== $entity) { // no clone, we have to fix
                        if (!$actualValue->isInitialized()) {
                            $actualValue->initialize(); // we have to do this otherwise the cols share state
                        }
                        $newValue = clone $actualValue;
                        $newValue->setOwner($entity, $assoc);
                        $class->reflFields[$propName]->setValue($entity, $newValue);
                    }
                }

                if ($orgValue instanceof PersistentCollection) {
                    // A PersistentCollection was de-referenced, so delete it.
                    $coid = spl_object_hash($orgValue);

                    if (isset($this->collectionDeletions[$coid])) {
                        continue;
                    }

                    $this->collectionDeletions[$coid] = $orgValue;
                    $changeSet[$propName] = $orgValue; // Signal changeset, to-many assocs will be ignored.

                    continue;
                }

                if ($assoc['type'] & ClassMetadata::TO_ONE) {
                    if ($assoc['isOwningSide']) {
                        $changeSet[$propName] = array($orgValue, $actualValue);
                    }

                    if ($orgValue !== null && $assoc['orphanRemoval']) {
                        $this->scheduleOrphanRemoval($orgValue);
                    }
                }
            }

            if ($changeSet) {
                $this->entityChangeSets[$oid]   = $changeSet;
                $this->originalEntityData[$oid] = $actualData;
                $this->entityUpdates[$oid]      = $entity;
            }
        }

        // Look for changes in associations of the entity
        foreach ($class->associationMappings as $field => $assoc) {
            if (($val = $class->reflFields[$field]->getValue($entity)) !== null) {
                $this->computeAssociationChanges($assoc, $val);
                if (!isset($this->entityChangeSets[$oid]) &&
                    $assoc['isOwningSide'] &&
                    $assoc['type'] == ClassMetadata::MANY_TO_MANY &&
                    $val instanceof PersistentCollection &&
                    $val->isDirty()) {
                    $this->entityChangeSets[$oid]   = array();
                    $this->originalEntityData[$oid] = $actualData;
                    $this->entityUpdates[$oid]      = $entity;
                }
            }
        }
    }

    /**
     * Computes all the changes that have been done to entities and collections
     * since the last commit and stores these changes in the _entityChangeSet map
     * temporarily for access by the persisters, until the UoW commit is finished.
     */
    public function computeChangeSets()
    {
        // Compute changes for INSERTed entities first. This must always happen.
        $this->computeScheduleInsertsChangeSets();

        // Compute changes for other MANAGED entities. Change tracking policies take effect here.
        foreach ($this->identityMap as $className => $entities) {
            $class = $this->em->getClassMetadata($className);

            // Skip class if instances are read-only
            if ($class->isReadOnly) {
                continue;
            }

            // If change tracking is explicit or happens through notification, then only compute
            // changes on entities of that type that are explicitly marked for synchronization.
            switch (true) {
                case ($class->isChangeTrackingDeferredImplicit()):
                    $entitiesToProcess = $entities;
                    break;

                case (isset($this->scheduledForDirtyCheck[$className])):
                    $entitiesToProcess = $this->scheduledForDirtyCheck[$className];
                    break;

                default:
                    $entitiesToProcess = array();

            }

            foreach ($entitiesToProcess as $entity) {
                // Ignore uninitialized proxy objects
                if ($entity instanceof Proxy && ! $entity->__isInitialized__) {
                    continue;
                }

                // Only MANAGED entities that are NOT SCHEDULED FOR INSERTION are processed here.
                $oid = spl_object_hash($entity);

                if ( ! isset($this->entityInsertions[$oid]) && isset($this->entityStates[$oid])) {
                    $this->computeChangeSet($class, $entity);
                }
            }
        }
    }

    /**
     * Computes the changes of an association.
     *
     * @param array $assoc
     * @param mixed $value The value of the association.
     *
     * @throws ORMInvalidArgumentException
     * @throws ORMException
     *
     * @return void
     */
    private function computeAssociationChanges($assoc, $value)
    {
        if ($value instanceof Proxy && ! $value->__isInitialized__) {
            return;
        }

        if ($value instanceof PersistentCollection && $value->isDirty()) {
            $coid = spl_object_hash($value);

            if ($assoc['isOwningSide']) {
                $this->collectionUpdates[$coid] = $value;
            }

            $this->visitedCollections[$coid] = $value;
        }

        // Look through the entities, and in any of their associations,
        // for transient (new) entities, recursively. ("Persistence by reachability")
        // Unwrap. Uninitialized collections will simply be empty.
        $unwrappedValue = ($assoc['type'] & ClassMetadata::TO_ONE) ? array($value) : $value->unwrap();
        $targetClass    = $this->em->getClassMetadata($assoc['targetEntity']);

        foreach ($unwrappedValue as $key => $entry) {
            $state = $this->getEntityState($entry, self::STATE_NEW);

            if ( ! ($entry instanceof $assoc['targetEntity'])) {
                throw new ORMException(
                    sprintf(
                        'Found entity of type %s on association %s#%s, but expecting %s',
                        get_class($entry),
                        $assoc['sourceEntity'],
                        $assoc['fieldName'],
                        $targetClass->name
                    )
                );
            }

            switch ($state) {
                case self::STATE_NEW:
                    if ( ! $assoc['isCascadePersist']) {
                        throw ORMInvalidArgumentException::newEntityFoundThroughRelationship($assoc, $entry);
                    }

                    $this->persistNew($targetClass, $entry);
                    $this->computeChangeSet($targetClass, $entry);
                    break;

                case self::STATE_REMOVED:
                    // Consume the $value as array (it's either an array or an ArrayAccess)
                    // and remove the element from Collection.
                    if ($assoc['type'] & ClassMetadata::TO_MANY) {
                        unset($value[$key]);
                    }
                    break;

                case self::STATE_DETACHED:
                    // Can actually not happen right now as we assume STATE_NEW,
                    // so the exception will be raised from the DBAL layer (constraint violation).
                    throw ORMInvalidArgumentException::detachedEntityFoundThroughRelationship($assoc, $entry);
                    break;

                default:
                    // MANAGED associated entities are already taken into account
                    // during changeset calculation anyway, since they are in the identity map.
            }
        }
    }

    /**
     * @param ClassMetadata $class
     * @param object $entity
     */
    private function persistNew($class, $entity)
    {
        $oid = spl_object_hash($entity);

        if (isset($class->lifecycleCallbacks[Events::prePersist])) {
            $class->invokeLifecycleCallbacks(Events::prePersist, $entity);
        }

        if ($this->evm->hasListeners(Events::prePersist)) {
            $this->evm->dispatchEvent(Events::prePersist, new LifecycleEventArgs($entity, $this->em));
        }

        $idGen = $class->idGenerator;

        if ( ! $idGen->isPostInsertGenerator()) {
            $idValue = $idGen->generate($this->em, $entity);

            if ( ! $idGen instanceof \Doctrine\ORM\Id\AssignedGenerator) {
                $idValue = array($class->identifier[0] => $idValue);

                $class->setIdentifierValues($entity, $idValue);
            }

            $this->entityIdentifiers[$oid] = $idValue;
        }

        $this->entityStates[$oid] = self::STATE_MANAGED;

        $this->scheduleForInsert($entity);
    }

    /**
     * INTERNAL:
     * Computes the changeset of an individual entity, independently of the
     * computeChangeSets() routine that is used at the beginning of a UnitOfWork#commit().
     *
     * The passed entity must be a managed entity. If the entity already has a change set
     * because this method is invoked during a commit cycle then the change sets are added.
     * whereby changes detected in this method prevail.
     *
     * @ignore
     * @param ClassMetadata $class The class descriptor of the entity.
     * @param object $entity The entity for which to (re)calculate the change set.
     *
     * @throws ORMInvalidArgumentException If the passed entity is not MANAGED.
     */
    public function recomputeSingleEntityChangeSet(ClassMetadata $class, $entity)
    {
        $oid = spl_object_hash($entity);

        if ( ! isset($this->entityStates[$oid]) || $this->entityStates[$oid] != self::STATE_MANAGED) {
            throw ORMInvalidArgumentException::entityNotManaged($entity);
        }

        // skip if change tracking is "NOTIFY"
        if ($class->isChangeTrackingNotify()) {
            return;
        }

        if ( ! $class->isInheritanceTypeNone()) {
            $class = $this->em->getClassMetadata(get_class($entity));
        }

        $actualData = array();

        foreach ($class->reflFields as $name => $refProp) {
            if ( ! $class->isIdentifier($name) || ! $class->isIdGeneratorIdentity()) {
                $actualData[$name] = $refProp->getValue($entity);
            }
        }

        $originalData = $this->originalEntityData[$oid];
        $changeSet = array();

        foreach ($actualData as $propName => $actualValue) {
            $orgValue = isset($originalData[$propName]) ? $originalData[$propName] : null;

            if (is_object($orgValue) && $orgValue !== $actualValue) {
                $changeSet[$propName] = array($orgValue, $actualValue);
            } else if ($orgValue != $actualValue || ($orgValue === null ^ $actualValue === null)) {
                $changeSet[$propName] = array($orgValue, $actualValue);
            }
        }

        if ($changeSet) {
            if (isset($this->entityChangeSets[$oid])) {
                $this->entityChangeSets[$oid] = array_merge($this->entityChangeSets[$oid], $changeSet);
            }

            $this->originalEntityData[$oid] = $actualData;
        }
    }

    /**
     * Executes all entity insertions for entities of the specified type.
     *
     * @param \Doctrine\ORM\Mapping\ClassMetadata $class
     */
    private function executeInserts($class)
    {
        $className = $class->name;
        $persister = $this->getEntityPersister($className);
        $entities  = array();

        $hasLifecycleCallbacks = isset($class->lifecycleCallbacks[Events::postPersist]);
        $hasListeners          = $this->evm->hasListeners(Events::postPersist);

        foreach ($this->entityInsertions as $oid => $entity) {
            if ($this->em->getClassMetadata(get_class($entity))->name !== $className) {
                continue;
            }

            $persister->addInsert($entity);

            unset($this->entityInsertions[$oid]);

            if ($hasLifecycleCallbacks || $hasListeners) {
                $entities[] = $entity;
            }
        }

        $postInsertIds = $persister->executeInserts();

        if ($postInsertIds) {
            // Persister returned post-insert IDs
            foreach ($postInsertIds as $id => $entity) {
                $oid     = spl_object_hash($entity);
                $idField = $class->identifier[0];

                $class->reflFields[$idField]->setValue($entity, $id);

                $this->entityIdentifiers[$oid] = array($idField => $id);
                $this->entityStates[$oid] = self::STATE_MANAGED;
                $this->originalEntityData[$oid][$idField] = $id;

                $this->addToIdentityMap($entity);
            }
        }

        foreach ($entities as $entity) {
            if ($hasLifecycleCallbacks) {
                $class->invokeLifecycleCallbacks(Events::postPersist, $entity);
            }

            if ($hasListeners) {
                $this->evm->dispatchEvent(Events::postPersist, new LifecycleEventArgs($entity, $this->em));
            }
        }
    }

    /**
     * Executes all entity updates for entities of the specified type.
     *
     * @param \Doctrine\ORM\Mapping\ClassMetadata $class
     */
    private function executeUpdates($class)
    {
        $className = $class->name;
        $persister = $this->getEntityPersister($className);

        $hasPreUpdateLifecycleCallbacks = isset($class->lifecycleCallbacks[Events::preUpdate]);
        $hasPreUpdateListeners          = $this->evm->hasListeners(Events::preUpdate);

        $hasPostUpdateLifecycleCallbacks = isset($class->lifecycleCallbacks[Events::postUpdate]);
        $hasPostUpdateListeners          = $this->evm->hasListeners(Events::postUpdate);

        foreach ($this->entityUpdates as $oid => $entity) {
            if ($this->em->getClassMetadata(get_class($entity))->name !== $className) {
                continue;
            }

            if ($hasPreUpdateLifecycleCallbacks) {
                $class->invokeLifecycleCallbacks(Events::preUpdate, $entity);

                $this->recomputeSingleEntityChangeSet($class, $entity);
            }

            if ($hasPreUpdateListeners) {
                $this->evm->dispatchEvent(
                    Events::preUpdate,
                    new Event\PreUpdateEventArgs($entity, $this->em, $this->entityChangeSets[$oid])
                );
            }

            if (!empty($this->entityChangeSets[$oid])) {
                $persister->update($entity);
            }

            unset($this->entityUpdates[$oid]);

            if ($hasPostUpdateLifecycleCallbacks) {
                $class->invokeLifecycleCallbacks(Events::postUpdate, $entity);
            }

            if ($hasPostUpdateListeners) {
                $this->evm->dispatchEvent(Events::postUpdate, new LifecycleEventArgs($entity, $this->em));
            }
        }
    }

    /**
     * Executes all entity deletions for entities of the specified type.
     *
     * @param \Doctrine\ORM\Mapping\ClassMetadata $class
     */
    private function executeDeletions($class)
    {
        $className = $class->name;
        $persister = $this->getEntityPersister($className);

        $hasLifecycleCallbacks = isset($class->lifecycleCallbacks[Events::postRemove]);
        $hasListeners = $this->evm->hasListeners(Events::postRemove);

        foreach ($this->entityDeletions as $oid => $entity) {
            if ($this->em->getClassMetadata(get_class($entity))->name !== $className) {
                continue;
            }

            $persister->delete($entity);

            unset(
                $this->entityDeletions[$oid],
                $this->entityIdentifiers[$oid],
                $this->originalEntityData[$oid],
                $this->entityStates[$oid]
            );

            // Entity with this $oid after deletion treated as NEW, even if the $oid
            // is obtained by a new entity because the old one went out of scope.
            //$this->entityStates[$oid] = self::STATE_NEW;
            if ( ! $class->isIdentifierNatural()) {
                $class->reflFields[$class->identifier[0]]->setValue($entity, null);
            }

            if ($hasLifecycleCallbacks) {
                $class->invokeLifecycleCallbacks(Events::postRemove, $entity);
            }

            if ($hasListeners) {
                $this->evm->dispatchEvent(Events::postRemove, new LifecycleEventArgs($entity, $this->em));
            }
        }
    }

    /**
     * Gets the commit order.
     *
     * @param array $entityChangeSet
     *
     * @return array
     */
    private function getCommitOrder(array $entityChangeSet = null)
    {
        if ($entityChangeSet === null) {
            $entityChangeSet = array_merge($this->entityInsertions, $this->entityUpdates, $this->entityDeletions);
        }

        $calc = $this->getCommitOrderCalculator();

        // See if there are any new classes in the changeset, that are not in the
        // commit order graph yet (dont have a node).
        // We have to inspect changeSet to be able to correctly build dependencies.
        // It is not possible to use IdentityMap here because post inserted ids
        // are not yet available.
        $newNodes = array();

        foreach ($entityChangeSet as $entity) {
            $className = $this->em->getClassMetadata(get_class($entity))->name;

            if ($calc->hasClass($className)) {
                continue;
            }

            $class = $this->em->getClassMetadata($className);
            $calc->addClass($class);

            $newNodes[] = $class;
        }

        // Calculate dependencies for new nodes
        while ($class = array_pop($newNodes)) {
            foreach ($class->associationMappings as $assoc) {
                if ( ! ($assoc['isOwningSide'] && $assoc['type'] & ClassMetadata::TO_ONE)) {
                    continue;
                }

                $targetClass = $this->em->getClassMetadata($assoc['targetEntity']);

                if ( ! $calc->hasClass($targetClass->name)) {
                    $calc->addClass($targetClass);

                    $newNodes[] = $targetClass;
                }

                $calc->addDependency($targetClass, $class);

                // If the target class has mapped subclasses, these share the same dependency.
                if ( ! $targetClass->subClasses) {
                    continue;
                }

                foreach ($targetClass->subClasses as $subClassName) {
                    $targetSubClass = $this->em->getClassMetadata($subClassName);

                    if ( ! $calc->hasClass($subClassName)) {
                        $calc->addClass($targetSubClass);

                        $newNodes[] = $targetSubClass;
                    }

                    $calc->addDependency($targetSubClass, $class);
                }
            }
        }

        return $calc->getCommitOrder();
    }

    /**
     * Schedules an entity for insertion into the database.
     * If the entity already has an identifier, it will be added to the identity map.
     *
     * @param object $entity The entity to schedule for insertion.
     *
     * @throws ORMInvalidArgumentException
     * @throws \InvalidArgumentException
     */
    public function scheduleForInsert($entity)
    {
        $oid = spl_object_hash($entity);

        if (isset($this->entityUpdates[$oid])) {
            throw new InvalidArgumentException("Dirty entity can not be scheduled for insertion.");
        }

        if (isset($this->entityDeletions[$oid])) {
            throw ORMInvalidArgumentException::scheduleInsertForRemovedEntity($entity);
        }
        if (isset($this->originalEntityData[$oid]) && ! isset($this->entityInsertions[$oid])) {
            throw ORMInvalidArgumentException::scheduleInsertForManagedEntity($entity);
        }

        if (isset($this->entityInsertions[$oid])) {
            throw ORMInvalidArgumentException::scheduleInsertTwice($entity);
        }

        $this->entityInsertions[$oid] = $entity;

        if (isset($this->entityIdentifiers[$oid])) {
            $this->addToIdentityMap($entity);
        }

        if ($entity instanceof NotifyPropertyChanged) {
            $entity->addPropertyChangedListener($this);
        }
    }

    /**
     * Checks whether an entity is scheduled for insertion.
     *
     * @param object $entity
     *
     * @return boolean
     */
    public function isScheduledForInsert($entity)
    {
        return isset($this->entityInsertions[spl_object_hash($entity)]);
    }

    /**
     * Schedules an entity for being updated.
     *
     * @param object $entity The entity to schedule for being updated.
     *
     * @throws ORMInvalidArgumentException
     */
    public function scheduleForUpdate($entity)
    {
        $oid = spl_object_hash($entity);

        if ( ! isset($this->entityIdentifiers[$oid])) {
            throw ORMInvalidArgumentException::entityHasNoIdentity($entity, "scheduling for update");
        }

        if (isset($this->entityDeletions[$oid])) {
            throw ORMInvalidArgumentException::entityIsRemoved($entity, "schedule for update");
        }

        if ( ! isset($this->entityUpdates[$oid]) && ! isset($this->entityInsertions[$oid])) {
            $this->entityUpdates[$oid] = $entity;
        }
    }

    /**
     * INTERNAL:
     * Schedules an extra update that will be executed immediately after the
     * regular entity updates within the currently running commit cycle.
     *
     * Extra updates for entities are stored as (entity, changeset) tuples.
     *
     * @ignore
     * @param object $entity The entity for which to schedule an extra update.
     * @param array $changeset The changeset of the entity (what to update).
     */
    public function scheduleExtraUpdate($entity, array $changeset)
    {
        $oid         = spl_object_hash($entity);
        $extraUpdate = array($entity, $changeset);

        if (isset($this->extraUpdates[$oid])) {
            list($ignored, $changeset2) = $this->extraUpdates[$oid];

            $extraUpdate = array($entity, $changeset + $changeset2);
        }

        $this->extraUpdates[$oid] = $extraUpdate;
    }

    /**
     * Checks whether an entity is registered as dirty in the unit of work.
     * Note: Is not very useful currently as dirty entities are only registered
     * at commit time.
     *
     * @param object $entity
     *
     * @return boolean
     */
    public function isScheduledForUpdate($entity)
    {
        return isset($this->entityUpdates[spl_object_hash($entity)]);
    }


    /**
     * Checks whether an entity is registered to be checked in the unit of work.
     *
     * @param object $entity
     *
     * @return boolean
     */
    public function isScheduledForDirtyCheck($entity)
    {
        $rootEntityName = $this->em->getClassMetadata(get_class($entity))->rootEntityName;

        return isset($this->scheduledForDirtyCheck[$rootEntityName][spl_object_hash($entity)]);
    }

    /**
     * INTERNAL:
     * Schedules an entity for deletion.
     *
     * @param object $entity
     */
    public function scheduleForDelete($entity)
    {
        $oid = spl_object_hash($entity);

        if (isset($this->entityInsertions[$oid])) {
            if ($this->isInIdentityMap($entity)) {
                $this->removeFromIdentityMap($entity);
            }

            unset($this->entityInsertions[$oid], $this->entityStates[$oid]);

            return; // entity has not been persisted yet, so nothing more to do.
        }

        if ( ! $this->isInIdentityMap($entity)) {
            return;
        }

        $this->removeFromIdentityMap($entity);

        if (isset($this->entityUpdates[$oid])) {
            unset($this->entityUpdates[$oid]);
        }

        if ( ! isset($this->entityDeletions[$oid])) {
            $this->entityDeletions[$oid] = $entity;
            $this->entityStates[$oid]    = self::STATE_REMOVED;
        }
    }

    /**
     * Checks whether an entity is registered as removed/deleted with the unit
     * of work.
     *
     * @param object $entity
     *
     * @return boolean
     */
    public function isScheduledForDelete($entity)
    {
        return isset($this->entityDeletions[spl_object_hash($entity)]);
    }

    /**
     * Checks whether an entity is scheduled for insertion, update or deletion.
     *
     * @param $entity
     *
     * @return boolean
     */
    public function isEntityScheduled($entity)
    {
        $oid = spl_object_hash($entity);

        return isset($this->entityInsertions[$oid])
            || isset($this->entityUpdates[$oid])
            || isset($this->entityDeletions[$oid]);
    }

    /**
     * INTERNAL:
     * Registers an entity in the identity map.
     * Note that entities in a hierarchy are registered with the class name of
     * the root entity.
     *
     * @ignore
     * @param object $entity  The entity to register.
     *
     * @throws ORMInvalidArgumentException
     *
     * @return boolean  TRUE if the registration was successful, FALSE if the identity of
     *                  the entity in question is already managed.
     */
    public function addToIdentityMap($entity)
    {
        $classMetadata = $this->em->getClassMetadata(get_class($entity));
        $idHash        = implode(' ', $this->entityIdentifiers[spl_object_hash($entity)]);

        if ($idHash === '') {
            throw ORMInvalidArgumentException::entityWithoutIdentity($classMetadata->name, $entity);
        }

        $className = $classMetadata->rootEntityName;

        if (isset($this->identityMap[$className][$idHash])) {
            return false;
        }

        $this->identityMap[$className][$idHash] = $entity;

        return true;
    }

    /**
     * Gets the state of an entity with regard to the current unit of work.
     *
     * @param object $entity
     * @param integer $assume The state to assume if the state is not yet known (not MANAGED or REMOVED).
     *                        This parameter can be set to improve performance of entity state detection
     *                        by potentially avoiding a database lookup if the distinction between NEW and DETACHED
     *                        is either known or does not matter for the caller of the method.
     *
     * @return int The entity state.
     */
    public function getEntityState($entity, $assume = null)
    {
        $oid = spl_object_hash($entity);

        if (isset($this->entityStates[$oid])) {
            return $this->entityStates[$oid];
        }

        if ($assume !== null) {
            return $assume;
        }

        // State can only be NEW or DETACHED, because MANAGED/REMOVED states are known.
        // Note that you can not remember the NEW or DETACHED state in _entityStates since
        // the UoW does not hold references to such objects and the object hash can be reused.
        // More generally because the state may "change" between NEW/DETACHED without the UoW being aware of it.
        $class = $this->em->getClassMetadata(get_class($entity));
        $id    = $class->getIdentifierValues($entity);

        if ( ! $id) {
            return self::STATE_NEW;
        }

        switch (true) {
            case ($class->isIdentifierNatural());
                // Check for a version field, if available, to avoid a db lookup.
                if ($class->isVersioned) {
                    return ($class->getFieldValue($entity, $class->versionField))
                        ? self::STATE_DETACHED
                        : self::STATE_NEW;
                }

                // Last try before db lookup: check the identity map.
                if ($this->tryGetById($id, $class->rootEntityName)) {
                    return self::STATE_DETACHED;
                }

                // db lookup
                if ($this->getEntityPersister($class->name)->exists($entity)) {
                    return self::STATE_DETACHED;
                }

                return self::STATE_NEW;

            case ( ! $class->idGenerator->isPostInsertGenerator()):
                // if we have a pre insert generator we can't be sure that having an id
                // really means that the entity exists. We have to verify this through
                // the last resort: a db lookup

                // Last try before db lookup: check the identity map.
                if ($this->tryGetById($id, $class->rootEntityName)) {
                    return self::STATE_DETACHED;
                }

                // db lookup
                if ($this->getEntityPersister($class->name)->exists($entity)) {
                    return self::STATE_DETACHED;
                }

                return self::STATE_NEW;

            default:
                return self::STATE_DETACHED;
        }
    }

    /**
     * INTERNAL:
     * Removes an entity from the identity map. This effectively detaches the
     * entity from the persistence management of Doctrine.
     *
     * @ignore
     * @param object $entity
     *
     * @throws ORMInvalidArgumentException
     *
     * @return boolean
     */
    public function removeFromIdentityMap($entity)
    {
        $oid           = spl_object_hash($entity);
        $classMetadata = $this->em->getClassMetadata(get_class($entity));
        $idHash        = implode(' ', $this->entityIdentifiers[$oid]);

        if ($idHash === '') {
            throw ORMInvalidArgumentException::entityHasNoIdentity($entity, "remove from identity map");
        }

        $className = $classMetadata->rootEntityName;

        if (isset($this->identityMap[$className][$idHash])) {
            unset($this->identityMap[$className][$idHash]);
            unset($this->readOnlyObjects[$oid]);

            //$this->entityStates[$oid] = self::STATE_DETACHED;

            return true;
        }

        return false;
    }

    /**
     * INTERNAL:
     * Gets an entity in the identity map by its identifier hash.
     *
     * @ignore
     * @param string $idHash
     * @param string $rootCl…