Fixes #4929: Optimize elgg_get_entities and add attribute loader

9 files changed, 349 insertions, 172 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 $row;
+	}
+}
diff --git a/engine/classes/ElggGroup.php b/engine/classes/ElggGroup.php
index 121186196..ea257f368 100644
--- a/engine/classes/ElggGroup.php
+++ b/engine/classes/ElggGroup.php
@@ -324,37 +324,18 @@ class ElggGroup extends ElggEntity
 	 * @return bool
 	 */
 	protected function load($guid) {
-		// Test to see if we have the generic stuff
-		if (!parent::load($guid)) {
-			return false;
-		}
+		$attr_loader = new ElggAttributeLoader(get_class(), 'group', $this->attributes);
+		$attr_loader->requires_access_control = !($this instanceof ElggPlugin);
+		$attr_loader->secondary_loader = 'get_group_entity_as_row';
 
-		// Only work with GUID from here
-		if ($guid instanceof stdClass) {
-			$guid = $guid->guid;
-		}
-
-		// Check the type
-		if ($this->attributes['type'] != 'group') {
-			$msg = elgg_echo('InvalidClassException:NotValidElggStar', array($guid, get_class()));
-			throw new InvalidClassException($msg);
-		}
-
-		// Load missing data
-		$row = get_group_entity_as_row($guid);
-		if (($row) && (!$this->isFullyLoaded())) {
-			// If $row isn't a cached copy then increment the counter
-			$this->attributes['tables_loaded']++;
-		}
-
-		// Now put these into the attributes array as core values
-		$objarray = (array) $row;
-		foreach ($objarray as $key => $value) {
-			$this->attributes[$key] = $value;
+		$attrs = $attr_loader->getRequiredAttributes($guid);
+		if (!$attrs) {
+			return false;
 		}
 
-		// guid needs to be an int  http://trac.elgg.org/ticket/4111
-		$this->attributes['guid'] = (int)$this->attributes['guid'];
+		$this->attributes = $attrs;
+		$this->attributes['tables_loaded'] = 2;
+		cache_entity($this);
 
 		return true;
 	}
diff --git a/engine/classes/ElggObject.php b/engine/classes/ElggObject.php
index fa6296c8c..84f6e09c8 100644
--- a/engine/classes/ElggObject.php
+++ b/engine/classes/ElggObject.php
@@ -99,37 +99,18 @@ class ElggObject extends ElggEntity {
 	 * @throws InvalidClassException
 	 */
 	protected function load($guid) {
-		// Load data from entity table if needed
-		if (!parent::load($guid)) {
-			return false;
-		}
+		$attr_loader = new ElggAttributeLoader(get_class(), 'object', $this->attributes);
+		$attr_loader->requires_access_control = !($this instanceof ElggPlugin);
+		$attr_loader->secondary_loader = 'get_object_entity_as_row';
 
-		// Only work with GUID from here
-		if ($guid instanceof stdClass) {
-			$guid = $guid->guid;
-		}
-
-		// Check the type
-		if ($this->attributes['type'] != 'object') {
-			$msg = elgg_echo('InvalidClassException:NotValidElggStar', array($guid, get_class()));
-			throw new InvalidClassException($msg);
-		}
-
-		// Load missing data
-		$row = get_object_entity_as_row($guid);
-		if (($row) && (!$this->isFullyLoaded())) {
-			// If $row isn't a cached copy then increment the counter
-			$this->attributes['tables_loaded']++;
-		}
-
-		// Now put these into the attributes array as core values
-		$objarray = (array) $row;
-		foreach ($objarray as $key => $value) {
-			$this->attributes[$key] = $value;
+		$attrs = $attr_loader->getRequiredAttributes($guid);
+		if (!$attrs) {
+			return false;
 		}
 
-		// guid needs to be an int  http://trac.elgg.org/ticket/4111
-		$this->attributes['guid'] = (int)$this->attributes['guid'];
+		$this->attributes = $attrs;
+		$this->attributes['tables_loaded'] = 2;
+		cache_entity($this);
 
 		return true;
 	}
diff --git a/engine/classes/ElggPlugin.php b/engine/classes/ElggPlugin.php
index 3e43c8e81..33f14ae37 100644
--- a/engine/classes/ElggPlugin.php
+++ b/engine/classes/ElggPlugin.php
@@ -79,64 +79,6 @@ class ElggPlugin extends ElggObject {
 	}
 
 	/**
-	 * Overridden from ElggEntity and ElggObject::load(). Core always inits plugins with
-	 * a query joined to the objects_entity table, so all the info is there.
-	 *
-	 * @param mixed $guid GUID of an ElggObject or the stdClass object from entities table
-	 *
-	 * @return bool
-	 * @throws InvalidClassException
-	 */
-	protected function load($guid) {
-
-		$expected_attributes = $this->attributes;
-		unset($expected_attributes['tables_split']);
-		unset($expected_attributes['tables_loaded']);
-
-		// this was loaded with a full join
-		$needs_loaded = false;
-
-		if ($guid instanceof stdClass) {
-			$row = (array) $guid;
-			$missing_attributes = array_diff_key($expected_attributes, $row);
-			if ($missing_attributes) {
-				$needs_loaded = true;
-				$guid = $row['guid'];
-			} else {
-				$this->attributes = $row;
-			}
-		} else {
-			$needs_loaded = true;
-		}
-
-		if ($needs_loaded) {
-			$entity = (array) get_entity_as_row($guid);
-			$object = (array) get_object_entity_as_row($guid);
-
-			if (!$entity || !$object) {
-				return false;
-			}
-			
-			$this->attributes = array_merge($this->attributes, $entity, $object);
-		}
-
-		$this->attributes['tables_loaded'] = 2;
-
-		// Check the type
-		if ($this->attributes['type'] != 'object') {
-			$msg = elgg_echo('InvalidClassException:NotValidElggStar', array($guid, get_class()));
-			throw new InvalidClassException($msg);
-		}
-
-		// guid needs to be an int  http://trac.elgg.org/ticket/4111
-		$this->attributes['guid'] = (int)$this->attributes['guid'];
-
-		cache_entity($this);
-
-		return true;
-	}
-
-	/**
 	 * Save the plugin object.  Make sure required values exist.
 	 *
 	 * @see ElggObject::save()
diff --git a/engine/classes/ElggSite.php b/engine/classes/ElggSite.php
index 401939005..f7f5b68ea 100644
--- a/engine/classes/ElggSite.php
+++ b/engine/classes/ElggSite.php
@@ -117,37 +117,18 @@ class ElggSite extends ElggEntity {
 	 * @throws InvalidClassException
 	 */
 	protected function load($guid) {
-		// Test to see if we have the generic stuff
-		if (!parent::load($guid)) {
-			return false;
-		}
+		$attr_loader = new ElggAttributeLoader(get_class(), 'site', $this->attributes);
+		$attr_loader->requires_access_control = !($this instanceof ElggPlugin);
+		$attr_loader->secondary_loader = 'get_site_entity_as_row';
 
-		// Only work with GUID from here
-		if ($guid instanceof stdClass) {
-			$guid = $guid->guid;
-		}
-
-		// Check the type
-		if ($this->attributes['type'] != 'site') {
-			$msg = elgg_echo('InvalidClassException:NotValidElggStar', array($guid, get_class()));
-			throw new InvalidClassException($msg);
-		}
-
-		// Load missing data
-		$row = get_site_entity_as_row($guid);
-		if (($row) && (!$this->isFullyLoaded())) {
-			// If $row isn't a cached copy then increment the counter
-			$this->attributes['tables_loaded']++;
-		}
-
-		// Now put these into the attributes array as core values
-		$objarray = (array) $row;
-		foreach ($objarray as $key => $value) {
-			$this->attributes[$key] = $value;
+		$attrs = $attr_loader->getRequiredAttributes($guid);
+		if (!$attrs) {
+			return false;
 		}
 
-		// guid needs to be an int  http://trac.elgg.org/ticket/4111
-		$this->attributes['guid'] = (int)$this->attributes['guid'];
+		$this->attributes = $attrs;
+		$this->attributes['tables_loaded'] = 2;
+		cache_entity($this);
 
 		return true;
 	}
diff --git a/engine/classes/ElggUser.php b/engine/classes/ElggUser.php
index d7bb89265..6c1cdc1de 100644
--- a/engine/classes/ElggUser.php
+++ b/engine/classes/ElggUser.php
@@ -106,37 +106,17 @@ class ElggUser extends ElggEntity
 	 * @return bool
 	 */
 	protected function load($guid) {
-		// Test to see if we have the generic stuff
-		if (!parent::load($guid)) {
-			return false;
-		}
+		$attr_loader = new ElggAttributeLoader(get_class(), 'user', $this->attributes);
+		$attr_loader->secondary_loader = 'get_user_entity_as_row';
 
-		// Only work with GUID from here
-		if ($guid instanceof stdClass) {
-			$guid = $guid->guid;
-		}
-
-		// Check the type
-		if ($this->attributes['type'] != 'user') {
-			$msg = elgg_echo('InvalidClassException:NotValidElggStar', array($guid, get_class()));
-			throw new InvalidClassException($msg);
-		}
-
-		// Load missing data
-		$row = get_user_entity_as_row($guid);
-		if (($row) && (!$this->isFullyLoaded())) {
-			// If $row isn't a cached copy then increment the counter
-			$this->attributes['tables_loaded']++;
-		}
-
-		// Now put these into the attributes array as core values
-		$objarray = (array) $row;
-		foreach ($objarray as $key => $value) {
-			$this->attributes[$key] = $value;
+		$attrs = $attr_loader->getRequiredAttributes($guid);
+		if (!$attrs) {
+			return false;
 		}
 
-		// guid needs to be an int  http://trac.elgg.org/ticket/4111
-		$this->attributes['guid'] = (int)$this->attributes['guid'];
+		$this->attributes = $attrs;
+		$this->attributes['tables_loaded'] = 2;
+		cache_entity($this);
 
 		return true;
 	}
diff --git a/engine/classes/IncompleteEntityException.php b/engine/classes/IncompleteEntityException.php
new file mode 100644
index 000000000..8c86edcc6
--- /dev/null
+++ b/engine/classes/IncompleteEntityException.php
@@ -0,0 +1,10 @@
+<?php
+/**
+ * IncompleteEntityException
+ * Thrown when constructing an entity that is missing its secondary entity table
+ *
+ * @package    Elgg.Core
+ * @subpackage Exception
+ * @access private
+ */
+class IncompleteEntityException extends Exception {}
diff --git a/engine/lib/entities.php b/engine/lib/entities.php
index a14160e14..70a950b16 100644
--- a/engine/lib/entities.php
+++ b/engine/lib/entities.php
@@ -735,7 +735,13 @@ function get_entity($guid) {
 		}
 	}
 
-	$new_entity = entity_row_to_elggstar($entity_row);
+	// don't let incomplete entities cause fatal exceptions
+	try {
+		$new_entity = entity_row_to_elggstar($entity_row);
+	} catch (IncompleteEntityException $e) {
+		return false;
+	}
+
 	if ($new_entity) {
 		cache_entity($new_entity);
 	}
@@ -980,7 +986,12 @@ function elgg_get_entities(array $options = array()) {
 			$query .= " LIMIT $offset, $limit";
 		}
 
-		$dt = get_data($query, $options['callback']);
+		if ($options['callback'] === 'entity_row_to_elggstar') {
+			$dt = _elgg_fetch_entities_from_sql($query);
+		} else {
+			$dt = get_data($query, $options['callback']);
+		}
+
 		if ($dt) {
 			// populate entity and metadata caches
 			$guids = array();
@@ -1009,6 +1020,97 @@ function elgg_get_entities(array $options = array()) {
 }
 
 /**
+ * Return entities from an SQL query generated by elgg_get_entities.
+ *
+ * @param string $sql
+ * @return ElggEntity[]
+ *
+ * @access private
+ * @throws LogicException
+ */
+function _elgg_fetch_entities_from_sql($sql) {
+	static $plugin_subtype;
+	if (null === $plugin_subtype) {
+		$plugin_subtype = get_subtype_id('object', 'plugin');
+	}
+
+	// Keys are types, values are columns that, if present, suggest that the secondary
+	// table is already JOINed
+	$types_to_optimize = array(
+		'object' => 'title',
+		'user' => 'password',
+		'group' => 'name',
+	);
+
+	$rows = get_data($sql);
+
+	// guids to look up in each type
+	$lookup_types = array();
+	// maps GUIDs to the $rows key
+	$guid_to_key = array();
+
+	if (isset($rows[0]->type, $rows[0]->subtype)
+			&& $rows[0]->type === 'object'
+			&& $rows[0]->subtype == $plugin_subtype) {
+		// Likely the entire resultset is plugins, which have already been optimized
+		// to JOIN the secondary table. In this case we allow retrieving from cache,
+		// but abandon the extra queries.
+		$types_to_optimize = array();
+	}
+
+	// First pass: use cache where possible, gather GUIDs that we're optimizing
+	foreach ($rows as $i => $row) {
+		if (empty($row->guid) || empty($row->type)) {
+			throw new LogicException('Entity row missing guid or type');
+		}
+		if ($entity = retrieve_cached_entity($row->guid)) {
+			$rows[$i] = $entity;
+			continue;
+		}
+		if (isset($types_to_optimize[$row->type])) {
+			// check if row already looks JOINed.
+			if (isset($row->{$types_to_optimize[$row->type]})) {
+				// Row probably already contains JOINed secondary table. Don't make another query just
+				// to pull data that's already there
+				continue;
+			}
+			$lookup_types[$row->type][] = $row->guid;
+			$guid_to_key[$row->guid] = $i;
+		}
+	}
+	// Do secondary queries and merge rows
+	if ($lookup_types) {
+		$dbprefix = elgg_get_config('dbprefix');
+	}
+	foreach ($lookup_types as $type => $guids) {
+		$set = "(" . implode(',', $guids) . ")";
+		$sql = "SELECT * FROM {$dbprefix}{$type}s_entity WHERE guid IN $set";
+		$secondary_rows = get_data($sql);
+		if ($secondary_rows) {
+			foreach ($secondary_rows as $secondary_row) {
+				$key = $guid_to_key[$secondary_row->guid];
+				// cast to arrays to merge then cast back
+				$rows[$key] = (object)array_merge((array)$rows[$key], (array)$secondary_row);
+			}
+		}
+	}
+	// Second pass to finish conversion
+	foreach ($rows as $i => $row) {
+		if ($row instanceof ElggEntity) {
+			continue;
+		} else {
+			try {
+				$rows[$i] = entity_row_to_elggstar($row);
+			} catch (IncompleteEntityException $e) {
+				// don't let incomplete entities throw fatal errors
+				unset($rows[$i]);
+			}
+		}
+	}
+	return $rows;
+}
+
+/**
  * Returns SQL where clause for type and subtype on main entity table
  *
  * @param string     $table    Entity table prefix as defined in SELECT...FROM entities $table
diff --git a/engine/lib/plugins.php b/engine/lib/plugins.php
index d5cd4fe76..cc1b4b9c7 100644
--- a/engine/lib/plugins.php
+++ b/engine/lib/plugins.php
@@ -190,6 +190,7 @@ function elgg_get_plugin_from_id($plugin_id) {
 		'type' => 'object',
 		'subtype' => 'plugin',
 		'joins' => array("JOIN {$db_prefix}objects_entity oe on oe.guid = e.guid"),
+		'selects' => array("oe.title", "oe.description"),
 		'wheres' => array("oe.title = '$plugin_id'"),
 		'limit' => 1
 	);