Fixes #4929: Optimize elgg_get_entities and add attribute loader

1 files changed, 199 insertions, 0 deletions

diff --git a/engine/classes/ElggAttributeLoader.php b/engine/classes/ElggAttributeLoader.php
new file mode 100644
index 000000000..602bb8bae
--- /dev/null
+++ b/engine/classes/ElggAttributeLoader.php
@@ -0,0 +1,199 @@
+<?php
+
+/**
+ * Loads ElggEntity attributes from DB or validates those passed in via constructor
+ *
+ * @access private
+ */
+class ElggAttributeLoader {
+
+	/**
+	 * @var array names of attributes in all entities
+	 */
+	protected static $primary_attr_names = array(
+		'guid',
+		'type',
+		'subtype',
+		'owner_guid',
+		'container_guid',
+		'site_guid',
+		'access_id',
+		'time_created',
+		'time_updated',
+		'last_action',
+		'enabled'
+	);
+
+	/**
+	 * @var array names of secondary attributes required for the entity
+	 */
+	protected $secondary_attr_names = array();
+
+	/**
+	 * @var string entity type (not class) required for fetched primaries
+	 */
+	protected $required_type;
+
+	/**
+	 * @var array
+	 */
+	protected $initialized_attributes;
+
+	/**
+	 * @var string class of object being loaded
+	 */
+	protected $class;
+
+	/**
+	 * @var bool should access control be considered when fetching entity?
+	 */
+	public $requires_access_control = true;
+
+	/**
+	 * @var callable function used to load attributes from {prefix}entities table
+	 */
+	public $primary_loader = 'get_entity_as_row';
+
+	/**
+	 * @var callable function used to load attributes from secondary table
+	 */
+	public $secondary_loader = '';
+
+	/**
+	 * @var callable function used to load all necessary attributes
+	 */
+	public $full_loader = '';
+
+	/**
+	 * @param string $class class of object being loaded
+	 * @param string $required_type entity type this is being used to populate
+	 * @param array $initialized_attrs attributes after initializeAttributes() has been run
+	 * @throws InvalidArgumentException
+	 */
+	public function __construct($class, $required_type, array $initialized_attrs) {
+		if (!is_string($class)) {
+			throw new InvalidArgumentException('$class must be a class name.');
+		}
+		$this->class = $class;
+
+		if (!is_string($required_type)) {
+			throw new InvalidArgumentException('$requiredType must be a system entity type.');
+		}
+		$this->required_type = $required_type;
+
+		$this->initialized_attributes = $initialized_attrs;
+		unset($initialized_attrs['tables_split'], $initialized_attrs['tables_loaded']);
+		$all_attr_names = array_keys($initialized_attrs);
+		$this->secondary_attr_names = array_diff($all_attr_names, self::$primary_attr_names);
+	}
+
+	protected function isMissingPrimaries($row) {
+		return array_diff(self::$primary_attr_names, array_keys($row)) !== array();
+	}
+
+	protected function isMissingSecondaries($row) {
+		return array_diff($this->secondary_attr_names, array_keys($row)) !== array();
+	}
+
+	protected function checkType($row) {
+		if ($row['type'] !== $this->required_type) {
+			$msg = elgg_echo('InvalidClassException:NotValidElggStar', array($row['guid'], $this->class));
+			throw new InvalidClassException($msg);
+		}
+	}
+
+	/**
+	 * Get all required attributes for the entity, validating any that are passed in. Returns empty array
+	 * if can't be loaded (Check $failure_reason).
+	 *
+	 * This function splits loading between "primary" attributes (those in {prefix}entities table) and
+	 * "secondary" attributes (e.g. those in {prefix}objects_entity), but can load all at once if a
+	 * combined loader is available.
+	 *
+	 * @param mixed $row a row loaded from DB (array or stdClass) or a GUID
+	 * @return array will be empty if failed to load all attributes (access control or entity doesn't exist)
+	 *
+	 * @throws InvalidArgumentException|LogicException|IncompleteEntityException
+	 */
+	public function getRequiredAttributes($row) {
+		if (!is_array($row) && !($row instanceof stdClass)) {
+			// assume row is the GUID
+			$row = array('guid' => $row);
+		}
+		$row = (array) $row;
+		if (empty($row['guid'])) {
+			throw new InvalidArgumentException('$row must be or contain a GUID');
+		}
+
+		// these must be present to support isFullyLoaded()
+		foreach (array('tables_split', 'tables_loaded') as $key) {
+			if (isset($this->initialized_attributes[$key])) {
+				$row[$key] = $this->initialized_attributes[$key];
+			}
+		}
+
+		$was_missing_primaries = $this->isMissingPrimaries($row);
+		$was_missing_secondaries = $this->isMissingSecondaries($row);
+
+		// some types have a function to load all attributes at once, it should be faster
+		if (($was_missing_primaries || $was_missing_secondaries) && is_callable($this->full_loader)) {
+			$fetched = (array) call_user_func($this->full_loader, $row['guid']);
+			if (!$fetched) {
+				return array();
+			}
+			$row = array_merge($row, $fetched);
+			$this->checkType($row);
+		} else {
+			if ($was_missing_primaries) {
+				if (!is_callable($this->primary_loader)) {
+					throw new LogicException('Primary attribute loader must be callable');
+				}
+				if (!$this->requires_access_control) {
+					$ignoring_access = elgg_set_ignore_access();
+				}
+				$fetched = (array) call_user_func($this->primary_loader, $row['guid']);
+				if (!$this->requires_access_control) {
+					elgg_set_ignore_access($ignoring_access);
+				}
+				if (!$fetched) {
+					return array();
+				}
+				$row = array_merge($row, $fetched);
+			}
+
+			// We must test type before trying to load the secondaries so that InvalidClassException
+			// gets thrown. Otherwise the secondary loader will fail and return false.
+			$this->checkType($row);
+
+			if ($was_missing_secondaries) {
+				if (!is_callable($this->secondary_loader)) {
+					throw new LogicException('Secondary attribute loader must be callable');
+				}
+				$fetched = (array) call_user_func($this->secondary_loader, $row['guid']);
+				if (!$fetched) {
+					if ($row['type'] === 'site') {
+						// A special case is needed for sites: When vanilla ElggEntities are created and
+						// saved, these are stored w/ type "site", but with no sites_entity row. These
+						// are probably only created in the unit tests.
+						// @todo Don't save vanilla ElggEntities with type "site"
+						$row['guid'] = (int) $row['guid'];
+						return $row;
+					}
+					throw new IncompleteEntityException("Secondary loader failed to return row for {$row['guid']}");
+				}
+				$row = array_merge($row, $fetched);
+			}
+		}
+
+		// loading complete: re-check missing and check type
+		if (($was_missing_primaries && $this->isMissingPrimaries($row))
+				|| ($was_missing_secondaries && $this->isMissingSecondaries($row))) {
+			throw new LogicException('Attribute loaders failed to return proper attributes');
+		}
+
+		// guid needs to be an int  http://trac.elgg.org/ticket/4111
+		$row['guid'] = (int) $row['guid'];
+
+		return $row;
+	}
+}