Made ClassMetadata to be reused during gatherRowData() and also during hydrateRow() to share same fetches instead of recalculating all info again. Performance improvement after 100x runs comparison is around 4%.

lib/Doctrine/ORM/Internal/Hydration/AbstractHydrator.php

@@ -64,6 +64,13 @@ abstract class AbstractHydrator
      */
     protected $_uow;
 
+    /**
+     * Local ClassMetadata cache to avoid going to the EntityManager all the time.
+     *
+     * @var array
+     */
+    protected $_metadataCache = array();
+
     /**
      * The cache used during row-by-row hydration.
      *
@@ -202,6 +209,7 @@ abstract class AbstractHydrator
         $this->_stmt          = null;
         $this->_rsm           = null;
         $this->_cache         = array();
+        $this->_metadataCache = array();
     }
 
     /**
@@ -403,12 +411,13 @@ abstract class AbstractHydrator
             // NOTE: Most of the times it's a field mapping, so keep it first!!!
             case (isset($this->_rsm->fieldMappings[$key])):
                 $fieldName     = $this->_rsm->fieldMappings[$key];
-                $classMetadata = $this->_em->getClassMetadata($this->_rsm->declaringClasses[$key]);
+                $classMetadata = $this->getClassMetadata($this->_rsm->declaringClasses[$key]);
+                $fieldMapping  = $classMetadata->fieldMappings[$fieldName];
 
                 return $this->_cache[$key] = array(
                     'isIdentifier' => $classMetadata->isIdentifier($fieldName),
                     'fieldName'    => $fieldName,
-                    'type'         => Type::getType($classMetadata->fieldMappings[$fieldName]['type']),
+                    'type'         => Type::getType($fieldMapping['type']),
                     'dqlAlias'     => $this->_rsm->columnOwnerMap[$key],
                 );
 
@@ -437,7 +446,7 @@ abstract class AbstractHydrator
                 // Meta column (has meaning in relational schema only, i.e. foreign keys or discriminator columns).
                 $fieldName     = $this->_rsm->metaMappings[$key];
                 $dqlAlias      = $this->_rsm->columnOwnerMap[$key];
-                $classMetadata = $this->_em->getClassMetadata($this->_rsm->aliasMap[$dqlAlias]);
+                $classMetadata = $this->getClassMetadata($this->_rsm->aliasMap[$dqlAlias]);
                 $type          = isset($this->_rsm->typeMappings[$key])
                     ? Type::getType($this->_rsm->typeMappings[$key])
                     : null;
@@ -456,6 +465,22 @@ abstract class AbstractHydrator
         return null;
     }
 
+    /**
+     * Retrieve ClassMetadata associated to entity class name.
+     *
+     * @param string $className
+     *
+     * @return \Doctrine\ORM\Mapping\ClassMetadata
+     */
+    protected function getClassMetadata($className)
+    {
+        if ( ! isset($this->_metadataCache[$className])) {
+            $this->_metadataCache[$className] = $this->_em->getClassMetadata($className);
+        }
+
+        return $this->_metadataCache[$className];
+    }
+
     /**
      * Register entity as managed in UnitOfWork.
      *

lib/Doctrine/ORM/Internal/Hydration/ArrayHydrator.php

@@ -32,11 +32,6 @@ use Doctrine\ORM\Mapping\ClassMetadata;
  */
 class ArrayHydrator extends AbstractHydrator
 {
-    /**
-     * @var array
-     */
-    private $_ce = array();
-
     /**
      * @var array
      */
@@ -314,20 +309,4 @@ class ArrayHydrator extends AbstractHydrator
 
         return;
     }
-
-    /**
-     * Retrieve ClassMetadata associated to entity class name.
-     *
-     * @param string $className
-     *
-     * @return \Doctrine\ORM\Mapping\ClassMetadata
-     */
-    private function getClassMetadata($className)
-    {
-        if ( ! isset($this->_ce[$className])) {
-            $this->_ce[$className] = $this->_em->getClassMetadata($className);
-        }
-
-        return $this->_ce[$className];
-    }
 }

lib/Doctrine/ORM/Internal/Hydration/ObjectHydrator.php

@@ -39,16 +39,6 @@ use Doctrine\ORM\Proxy\Proxy;
  */
 class ObjectHydrator extends AbstractHydrator
 {
-    /**
-     * Local ClassMetadata cache to avoid going to the EntityManager all the time.
-     * This local cache is maintained between hydration runs and not cleared.
-     *
-     * @var array
-     */
-    private $ce = array();
-
-    /* The following parts are reinitialized on every hydration run. */
-
     /**
      * @var array
      */
@@ -314,24 +304,6 @@ class ObjectHydrator extends AbstractHydrator
         }
     }
 
-    /**
-     * Gets a ClassMetadata instance from the local cache.
-     * If the instance is not yet in the local cache, it is loaded into the
-     * local cache.
-     *
-     * @param string $className The name of the class.
-     *
-     * @return ClassMetadata
-     */
-    private function getClassMetadata($className)
-    {
-        if ( ! isset($this->ce[$className])) {
-            $this->ce[$className] = $this->_em->getClassMetadata($className);
-        }
-
-        return $this->ce[$className];
-    }
-
     /**
      * Hydrates a single row in an SQL result set.
      *

lib/Doctrine/ORM/Internal/Hydration/ScalarHydrator.php

@@ -36,7 +36,6 @@ class ScalarHydrator extends AbstractHydrator
     protected function hydrateAllData()
     {
         $result = array();
-        $cache  = array();
 
         while ($data = $this->_stmt->fetch(\PDO::FETCH_ASSOC)) {
             $this->hydrateRowData($data, $result);

lib/Doctrine/ORM/Internal/Hydration/SingleScalarHydrator.php

@@ -51,8 +51,7 @@ class SingleScalarHydrator extends AbstractHydrator
             throw new NonUniqueResultException('The query returned a row containing multiple columns. Change the query or use a different result function like getScalarResult().');
         }
 
-        $cache  = array();
+        $result = $this->gatherScalarRowData($data[key($data)]);
-        $result = $this->gatherScalarRowData($data[key($data)], $cache);
 
         return array_shift($result);
     }