N°2272 - OQL performance (OQL class tree optimizer)

core/oqlclasstreeoptimizer.class.inc.php

@@ -0,0 +1,68 @@
+<?php
+/**
+ * @copyright   Copyright (C) 2010-2019 Combodo SARL
+ * @license     http://opensource.org/licenses/AGPL-3.0
+ */
+
+
+class OQLClassTreeOptimizer
+{
+    /** @var OQLClassNode */
+	private $oOQLClassNode;
+	/** @var QueryBuilderContext */
+	private $oBuild;
+
+	/**
+	 * OQLClassTreeOptimizer constructor.
+	 *
+	 * @param OQLClassNode $oOQLClassNode
+	 * @param QueryBuilderContext $oBuild
+	 */
+	public function __construct($oOQLClassNode, $oBuild)
+	{
+		$this->oOQLClassNode = $oOQLClassNode;
+		$this->oBuild = $oBuild;
+	}
+
+	/**
+	 * Prune the unnecessary joins
+	 */
+	public function OptimizeClassTree()
+	{
+		$this->PruneJoins($this->oOQLClassNode);
+	}
+
+	/**
+	 * @param OQLClassNode $oCurrentClassNode
+	 *
+	 * @return bool
+	 */
+	private function PruneJoins($oCurrentClassNode)
+	{
+		$aExpectedAttributes = $this->oBuild->m_oQBExpressions->GetUnresolvedFields($oCurrentClassNode->GetClassAlias());
+		$bCanBeRemoved = empty($aExpectedAttributes);
+
+		foreach ($oCurrentClassNode->GetJoins() as $index => $oJoin)
+		{
+			if ($this->PruneJoins($oJoin->GetOOQLClassNode()))
+			{
+				if ($oJoin->IsOutbound())
+				{
+					// The join is not used, remove from tree
+					$oCurrentClassNode->RemoveJoin($index);
+				}
+				else
+				{
+					// Inbound joins cannot be removed
+					$bCanBeRemoved = false;
+				}
+			}
+			else
+			{
+				// This join is used, so the current node cannot be removed
+				$bCanBeRemoved = false;
+			}
+		}
+		return $bCanBeRemoved;
+	}
+}