[DBAL-2546] Reworked implementation of closeCursor() for mysqli, ibm_db2 and oci drivers

lib/Doctrine/DBAL/Driver/IBMDB2/DB2Statement.php

@@ -104,11 +104,8 @@ class DB2Statement implements \IteratorAggregate, Statement
         }
 
         $this->_bindParam = array();
-        db2_free_result($this->_stmt);
-        $ret = db2_free_stmt($this->_stmt);
-        $this->_stmt = false;
 
-        return $ret;
+        return db2_free_result($this->_stmt);
     }
 
     /**

lib/Doctrine/DBAL/Driver/OCI8/OCI8Statement.php

@@ -176,7 +176,13 @@ class OCI8Statement implements \IteratorAggregate, Statement
      */
     public function closeCursor()
     {
-        return oci_free_statement($this->_sth);
+        // emulate it by fetching and discarding rows, similarly to what PDO does in this case
+        // @link http://php.net/manual/en/pdostatement.closecursor.php
+        // @link https://github.com/php/php-src/blob/php-7.0.11/ext/pdo/pdo_stmt.c#L2075
+        // deliberately do not consider multiple result sets, since doctrine/dbal doesn't support them
+        while (oci_fetch($this->_sth));
+
+        return true;
     }
 
     /**

lib/Doctrine/DBAL/Driver/SQLSrv/SQLSrvStatement.php

@@ -150,9 +150,13 @@ class SQLSrvStatement implements IteratorAggregate, Statement
      */
     public function closeCursor()
     {
-        if ($this->stmt) {
-            sqlsrv_free_stmt($this->stmt);
-        }
+        // emulate it by fetching and discarding rows, similarly to what PDO does in this case
+        // @link http://php.net/manual/en/pdostatement.closecursor.php
+        // @link https://github.com/php/php-src/blob/php-7.0.11/ext/pdo/pdo_stmt.c#L2075
+        // deliberately do not consider multiple result sets, since doctrine/dbal doesn't support them
+        while (sqlsrv_fetch($this->stmt));
+
+        return true;
     }
 
     /**

tests/Doctrine/Tests/DBAL/Functional/StatementTest.php

+<?php
+
+namespace Doctrine\Tests\DBAL\Functional;
+
+use Doctrine\DBAL\Schema\Table;
+
+class StatementTest extends \Doctrine\Tests\DbalFunctionalTestCase
+{
+    public function testStatementIsReusableAfterClosingCursor()
+    {
+        $sm = $this->_conn->getSchemaManager();
+        $table = new Table('stmt_test_reusable');
+        $table->addColumn('id', 'integer');
+        $sm->createTable($table);
+        $this->_conn->insert('stmt_test_reusable', array('id' => 1));
+        $this->_conn->insert('stmt_test_reusable', array('id' => 2));
+
+        $stmt = $this->_conn->prepare('SELECT id FROM stmt_test_reusable ORDER BY id');
+
+        $stmt->execute();
+
+        $id = $stmt->fetchColumn();
+        $this->assertEquals(1, $id);
+
+        $stmt->closeCursor();
+
+        $stmt->execute();
+        $id = $stmt->fetchColumn();
+        $this->assertEquals(1, $id);
+        $id = $stmt->fetchColumn();
+        $this->assertEquals(2, $id);
+    }
+
+    public function testClosedCursorDoesNotContainResults()
+    {
+        $sm = $this->_conn->getSchemaManager();
+        $table = new Table('stmt_test_no_results');
+        $table->addColumn('id', 'integer');
+        $sm->createTable($table);
+        $this->_conn->insert('stmt_test_no_results', array('id' => 1));
+
+        $stmt = $this->_conn->prepare('SELECT id FROM stmt_test_no_results');
+        $stmt->execute();
+        $stmt->closeCursor();
+
+        try {
+            $value = $stmt->fetchColumn();
+        } catch (\Exception $e) {
+            // some adapters trigger PHP error or throw adapter-specific exception in case of fetching
+            // from a closed cursor, which still proves that it has been closed
+            return;
+        }
+
+        $this->assertFalse($value);
+    }
+}