Add a log message when the Doctrine Query Builder is retrieved

lib/private/appframework/db/db.php

@@ -45,15 +45,6 @@ class Db implements IDb {
 		$this->connection = $connection;
 	}
 
-	/**
-	 * Gets the ExpressionBuilder for the connection.
-	 *
-	 * @return \OCP\DB\QueryBuilder\IExpressionBuilder
-	 */
-	public function getExpressionBuilder() {
-		return $this->connection->getExpressionBuilder();
-	}
-
 	/**
 	 * Gets the ExpressionBuilder for the connection.
 	 *

lib/private/db/connection.php

@@ -54,16 +54,7 @@ class Connection extends \Doctrine\DBAL\Connection implements IDBConnection {
 	}
 
 	/**
-	 * Gets the ExpressionBuilder for the connection.
-	 *
-	 * @return \OCP\DB\QueryBuilder\IExpressionBuilder
-	 */
-	public function getExpressionBuilder() {
-		return new ExpressionBuilder($this);
-	}
-
-	/**
-	 * Gets the QueryBuilder for the connection.
+	 * Returns a QueryBuilder for the connection.
 	 *
 	 * @return \OCP\DB\QueryBuilder\IQueryBuilder
 	 */
@@ -71,6 +62,47 @@ class Connection extends \Doctrine\DBAL\Connection implements IDBConnection {
 		return new QueryBuilder($this);
 	}
 
+	/**
+	 * Gets the QueryBuilder for the connection.
+	 *
+	 * @return \Doctrine\DBAL\Query\QueryBuilder
+	 * @deprecated please use $this->getQueryBuilder() instead
+	 */
+	public function createQueryBuilder() {
+		$backtrace = $this->getCallerBacktrace();
+		\OC::$server->getLogger()->debug('Doctrine QueryBuilder retrieved in {backtrace}', ['app' => 'core', 'backtrace' => $backtrace]);
+		return parent::createQueryBuilder();
+	}
+
+	/**
+	 * Gets the ExpressionBuilder for the connection.
+	 *
+	 * @return \Doctrine\DBAL\Query\Expression\ExpressionBuilder
+	 * @deprecated please use $this->getQueryBuilder()->expr() instead
+	 */
+	public function getExpressionBuilder() {
+		$backtrace = $this->getCallerBacktrace();
+		\OC::$server->getLogger()->debug('Doctrine ExpressionBuilder retrieved in {backtrace}', ['app' => 'core', 'backtrace' => $backtrace]);
+		return parent::getExpressionBuilder();
+	}
+
+	/**
+	 * Get the file and line that called the method where `getCallerBacktrace()` was used
+	 *
+	 * @return string
+	 */
+	protected function getCallerBacktrace() {
+		$traces = debug_backtrace(DEBUG_BACKTRACE_IGNORE_ARGS, 2);
+
+		// 0 is the method where we use `getCallerBacktrace`
+		// 1 is the target method which uses the method we want to log
+		if (isset($traces[1])) {
+			return $traces[1]['file'] . ':' . $traces[1]['line'];
+		}
+
+		return '';
+	}
+
 	/**
 	 * @return string
 	 */

lib/private/db/querybuilder/querybuilder.php

@@ -65,7 +65,7 @@ class QueryBuilder implements IQueryBuilder {
 	 * @return \OCP\DB\QueryBuilder\IExpressionBuilder
 	 */
 	public function expr() {
-		return $this->connection->getExpressionBuilder();
+		return new ExpressionBuilder($this->connection);
 	}
 
 	/**

lib/public/idbconnection.php

@@ -40,14 +40,6 @@ namespace OCP;
  * @since 6.0.0
  */
 interface IDBConnection {
-	/**
-	 * Gets the ExpressionBuilder for the connection.
-	 *
-	 * @return \OCP\DB\QueryBuilder\IExpressionBuilder
-	 * @since 8.2.0
-	 */
-	public function getExpressionBuilder();
-
 	/**
 	 * Gets the QueryBuilder for the connection.
 	 *