diff core/modules/field/field.purge.inc @ 0:4c8ae668cc8c

Initial import (non-working)

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/core/modules/field/field.purge.inc	Wed Nov 29 16:09:58 2017 +0000
@@ -0,0 +1,181 @@
+<?php
+
+/**
+ * @file
+ * Provides support for field data purge after mass deletion.
+ */
+
+use Drupal\Core\Field\FieldException;
+use Drupal\field\Entity\FieldStorageConfig;
+use Drupal\field\FieldStorageConfigInterface;
+use Drupal\field\FieldConfigInterface;
+
+/**
+ * @defgroup field_purge Field API bulk data deletion
+ * @{
+ * Cleans up after Field API bulk deletion operations.
+ *
+ * Field API provides functions for deleting data attached to individual
+ * entities as well as deleting entire fields or field storages in a single
+ * operation.
+ *
+ * When a single entity is deleted, the Entity storage performs the
+ * following operations:
+ * - Invoking the method \Drupal\Core\Field\FieldItemListInterface::delete() for
+ *   each field on the entity. A file field type might use this method to delete
+ *   uploaded files from the filesystem.
+ * - Removing the data from storage.
+ * - Invoking the global hook_entity_delete() for all modules that implement it.
+ *   Each hook implementation receives the entity being deleted and can operate
+ *   on whichever subset of the entity's bundle's fields it chooses to.
+ *
+ * Similar operations are performed on deletion of a single entity revision.
+ *
+ * When a bundle, field or field storage is deleted, it is not practical to
+ * perform those operations immediately on every affected entity in a single
+ * page request; there could be thousands or millions of them. Instead, the
+ * appropriate field data items, fields, and/or field storages are marked as
+ * deleted so that subsequent load or query operations will not return them.
+ * Later, a separate process cleans up, or "purges", the marked-as-deleted data
+ * by going through the three-step process described above and, finally,
+ * removing deleted field storage and field records.
+ *
+ * Purging field data is made somewhat tricky by the fact that, while
+ * $entity->delete() has a complete entity to pass to the various deletion
+ * steps, the Field API purge process only has the field data it has previously
+ * stored. It cannot reconstruct complete original entities to pass to the
+ * deletion operations. It is even possible that the original entity to which
+ * some Field API data was attached has been itself deleted before the field
+ * purge operation takes place.
+ *
+ * Field API resolves this problem by using stub entities during purge
+ * operations, containing only the information from the original entity that
+ * Field API knows about: entity type, ID, revision ID, and bundle. It also
+ * contains the field data for whichever field is currently being purged.
+ *
+ * See @link field Field API @endlink for information about the other parts of
+ * the Field API.
+ */
+
+/**
+ * Purges a batch of deleted Field API data, field storages, or fields.
+ *
+ * This function will purge deleted field data in batches. The batch size
+ * is defined as an argument to the function, and once each batch is finished,
+ * it continues with the next batch until all have completed. If a deleted field
+ * with no remaining data records is found, the field itself will
+ * be purged. If a deleted field storage with no remaining fields is found, the
+ * field storage itself will be purged.
+ *
+ * @param $batch_size
+ *   The maximum number of field data records to purge before returning.
+ * @param string $field_storage_uuid
+ *   (optional) Limit the purge to a specific field storage.
+ */
+function field_purge_batch($batch_size, $field_storage_uuid = NULL) {
+  $properties = [
+    'deleted' => TRUE,
+    'include_deleted' => TRUE,
+  ];
+  if ($field_storage_uuid) {
+    $properties['field_storage_uuid'] = $field_storage_uuid;
+  }
+  $fields = entity_load_multiple_by_properties('field_config', $properties);
+
+  $info = \Drupal::entityManager()->getDefinitions();
+  foreach ($fields as $field) {
+    $entity_type = $field->getTargetEntityTypeId();
+
+    // We cannot purge anything if the entity type is unknown (e.g. the
+    // providing module was uninstalled).
+    // @todo Revisit after https://www.drupal.org/node/2080823.
+    if (!isset($info[$entity_type])) {
+      continue;
+    }
+
+    $count_purged = \Drupal::entityManager()->getStorage($entity_type)->purgeFieldData($field, $batch_size);
+    if ($count_purged < $batch_size || $count_purged == 0) {
+      // No field data remains for the field, so we can remove it.
+      field_purge_field($field);
+    }
+    $batch_size -= $count_purged;
+    // Only delete up to the maximum number of records.
+    if ($batch_size == 0) {
+      break;
+    }
+  }
+
+  // Retrieve all deleted field storages. Any that have no fields can be purged.
+  $deleted_storages = \Drupal::state()->get('field.storage.deleted') ?: [];
+  foreach ($deleted_storages as $field_storage) {
+    $field_storage = new FieldStorageConfig($field_storage);
+    if ($field_storage_uuid && $field_storage->uuid() != $field_storage_uuid) {
+      // If a specific UUID is provided, only purge the corresponding field.
+      continue;
+    }
+
+    // We cannot purge anything if the entity type is unknown (e.g. the
+    // providing module was uninstalled).
+    // @todo Revisit after https://www.drupal.org/node/2080823.
+    if (!isset($info[$field_storage->getTargetEntityTypeId()])) {
+      continue;
+    }
+
+    $fields = entity_load_multiple_by_properties('field_config', ['field_storage_uuid' => $field_storage->uuid(), 'include_deleted' => TRUE]);
+    if (empty($fields)) {
+      field_purge_field_storage($field_storage);
+    }
+  }
+}
+
+/**
+ * Purges a field record from the database.
+ *
+ * This function assumes all data for the field has already been purged and
+ * should only be called by field_purge_batch().
+ *
+ * @param $field
+ *   The field record to purge.
+ */
+function field_purge_field(FieldConfigInterface $field) {
+  $state = \Drupal::state();
+  $deleted_fields = $state->get('field.field.deleted');
+  unset($deleted_fields[$field->uuid()]);
+  $state->set('field.field.deleted', $deleted_fields);
+
+  // Invoke external hooks after the cache is cleared for API consistency.
+  \Drupal::moduleHandler()->invokeAll('field_purge_field', [$field]);
+}
+
+/**
+ * Purges a field record from the database.
+ *
+ * This function assumes all fields for the field storage has already been
+ * purged, and should only be called by field_purge_batch().
+ *
+ * @param \Drupal\field\FieldStorageConfigInterface $field_storage
+ *   The field storage to purge.
+ *
+ * @throws Drupal\field\FieldException
+ */
+function field_purge_field_storage(FieldStorageConfigInterface $field_storage) {
+  $fields = entity_load_multiple_by_properties('field_config', ['field_storage_uuid' => $field_storage->uuid(), 'include_deleted' => TRUE]);
+  if (count($fields) > 0) {
+    throw new FieldException(t('Attempt to purge a field storage @field_name that still has fields.', ['@field_name' => $field_storage->getName()]));
+  }
+
+  $state = \Drupal::state();
+  $deleted_storages = $state->get('field.storage.deleted');
+  unset($deleted_storages[$field_storage->uuid()]);
+  $state->set('field.storage.deleted', $deleted_storages);
+
+  // Notify the storage layer.
+  \Drupal::entityManager()->getStorage($field_storage->getTargetEntityTypeId())->finalizePurge($field_storage);
+
+  // Invoke external hooks after the cache is cleared for API consistency.
+  \Drupal::moduleHandler()->invokeAll('field_purge_field_storage', [$field_storage]);
+}
+
+/**
+ * @} End of "defgroup field_purge".
+ */