From 7a8a938077150b1cfd0994f60afbc8f916dafe94 Mon Sep 17 00:00:00 2001
From: "Eloy Lafuente (stronk7)" <stronk7@moodle.org>
Date: Thu, 1 Sep 2011 11:05:21 +0200
Subject: [PATCH] MDL-29198 DB - make delete_records transactional safe when
 needed

---
 lib/dml/moodle_database.php    |  4 +++-
 lib/dml/simpletest/testdml.php | 19 +++++++++++++++++++
 2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/lib/dml/moodle_database.php b/lib/dml/moodle_database.php
index db88a9efe7b..d8bb8348205 100644
--- a/lib/dml/moodle_database.php
+++ b/lib/dml/moodle_database.php
@@ -1595,7 +1595,9 @@ abstract class moodle_database {
      * @throws dml_exception if error
      */
     public function delete_records($table, array $conditions=null) {
-        if (is_null($conditions)) {
+        // truncate is drop/create (DDL), not transactional safe,
+        // so we don't use the shortcut within them. MDL-29198
+        if (is_null($conditions) && empty($this->transactions)) {
             return $this->execute("TRUNCATE TABLE {".$table."}");
         }
         list($select, $params) = $this->where_clause($table, $conditions);
diff --git a/lib/dml/simpletest/testdml.php b/lib/dml/simpletest/testdml.php
index 40ba8557a28..eb3f555e455 100644
--- a/lib/dml/simpletest/testdml.php
+++ b/lib/dml/simpletest/testdml.php
@@ -3851,6 +3851,25 @@ class dml_test extends UnitTestCase {
         $transaction->allow_commit();
         $this->assertEqual(2, $DB2->count_records($tablename));
 
+        // let's try delete all is also working on (this checks MDL-29198)
+        // initially both connections see all the records in the table (2)
+        $this->assertEqual(2, $DB->count_records($tablename));
+        $this->assertEqual(2, $DB2->count_records($tablename));
+        $transaction = $DB->start_delegated_transaction();
+
+        // delete all from within transaction
+        $DB->delete_records($tablename);
+
+        // transactional $DB, sees 0 records now
+        $this->assertEqual(0, $DB->count_records($tablename));
+
+        // others ($DB2) get no changes yet
+        $this->assertEqual(2, $DB2->count_records($tablename));
+
+        // now commit and we should see changes
+        $transaction->allow_commit();
+        $this->assertEqual(0, $DB2->count_records($tablename));
+
         $DB2->dispose();
     }