### Eclipse Workspace Patch 1.0
#P moodle20
Index: lib/dml/simpletest/testdml.php
===================================================================
RCS file: /cvsroot/moodle/moodle/lib/dml/simpletest/testdml.php,v
retrieving revision 1.56
diff -u -r1.56 testdml.php
--- lib/dml/simpletest/testdml.php	16 Oct 2009 14:16:18 -0000	1.56
+++ lib/dml/simpletest/testdml.php	22 Oct 2009 15:25:13 -0000
@@ -2332,6 +2332,94 @@
             $this->assertTrue(true, 'DB Transactions not supported. Test skipped');
         }
     }
+
+    function test_nested_transactions() {
+        $DB = $this->tdb;
+        $dbman = $DB->get_manager();
+
+        $table = $this->get_test_table();
+        $tablename = $table->getName();
+
+        $table->add_field('id', XMLDB_TYPE_INTEGER, '10', XMLDB_UNSIGNED, XMLDB_NOTNULL, XMLDB_SEQUENCE, null);
+        $table->add_field('course', XMLDB_TYPE_INTEGER, '10', XMLDB_UNSIGNED, XMLDB_NOTNULL, null, '0');
+        $table->add_key('primary', XMLDB_KEY_PRIMARY, array('id'));
+        $dbman->create_table($table);
+        $this->tables[$tablename] = $table;
+
+        $active = $DB->begin_sql();
+        if ($active) {
+            // test only if driver supports transactions
+
+            //two level rollback
+            $data = (object)array('course'=>3);
+            $DB->insert_record($tablename, $data);
+            $DB->begin_sql();
+            $data = (object)array('course'=>4);
+            $DB->insert_record($tablename, $data);
+            $DB->commit_sql();
+            $DB->rollback_sql();
+            $this->assertEqual(0, $DB->count_records($tablename));
+
+            $DB->delete_records($tablename);
+
+            // rollback from nested level
+            $DB->begin_sql();
+            $data = (object)array('course'=>3);
+            $DB->insert_record($tablename, $data);
+            $DB->begin_sql();
+            $data = (object)array('course'=>4);
+            $DB->insert_record($tablename, $data);
+            try {
+                $DB->rollback_sql();
+            } catch (Exception $e) {
+                $this->assertTrue($e instanceof nested_rollback_exception);
+            }
+            // normally you would not commit the transaction when exception caught
+            // but for the purpose of testing we commit and make sure the data is
+            // not rolled back in nested exception
+            $DB->commit_sql();
+            $this->assertEqual(2, $DB->count_records($tablename));
+
+            $DB->delete_records($tablename);
+
+            $DB->begin_sql();
+            $data = (object)array('course'=>3);
+            $DB->insert_record($tablename, $data);
+            $DB->begin_sql();
+            $data = (object)array('course'=>4);
+            $DB->insert_record($tablename, $data);
+            $DB->commit_sql();
+            $DB->commit_sql();
+            $this->assertEqual(2, $DB->count_records($tablename));
+        } else {
+
+            $this->assertTrue(true, 'DB Transactions not supported. Test skipped');
+        }
+    }
+
+    function test_transaction_auto_rollback_on_error() {
+        $DB = $this->tdb;
+
+        $DB->begin_sql();
+        $DB->begin_sql();
+        $DB->begin_sql();
+
+        //floowing code is copy/pasted from the default_exception_handler()
+        $i = 0;
+        while($DB->is_transaction_started()) {
+            $i++;
+            if ($i > 3) {
+                $this->fail('Force closing transaction failed');
+                break;
+            }
+            //nested transactions throw exceptions, we need to traverse to the top level exception
+            try {
+                $DB->rollback_sql();
+            } catch (Exception $ignored) {
+            }
+        }
+        $this->assertEqual(3, $i);
+    }
 }
 
 /**
Index: lib/dml/pgsql_native_moodle_database.php
===================================================================
RCS file: /cvsroot/moodle/moodle/lib/dml/pgsql_native_moodle_database.php,v
retrieving revision 1.41
diff -u -r1.41 pgsql_native_moodle_database.php
--- lib/dml/pgsql_native_moodle_database.php	16 Oct 2009 14:14:03 -0000	1.41
+++ lib/dml/pgsql_native_moodle_database.php	22 Oct 2009 15:25:11 -0000
@@ -1130,9 +1130,12 @@
      * this is _very_ useful for massive updates
      */
     public function begin_sql() {
-        if (!parent::begin_sql()) {
-            return false;
+        parent::begin_sql();
+        if ($this->intransaction > 1) {
+            // do not start transactions in nested levels
+            return true;
         }
+
         $sql = "BEGIN ISOLATION LEVEL READ COMMITTED";
         $this->query_start($sql, NULL, SQL_QUERY_AUX);
         $result = pg_query($this->pgsql, $sql);
@@ -1146,9 +1149,12 @@
      * on DBs that support it, commit the transaction
      */
     public function commit_sql() {
-        if (!parent::commit_sql()) {
-            return false;
+        parent::commit_sql();
+        if ($this->intransaction > 0) {
+            //nested transactions do not commit, only the top most one 
+            return true;
         }
+
         $sql = "COMMIT";
         $this->query_start($sql, NULL, SQL_QUERY_AUX);
         $result = pg_query($this->pgsql, $sql);
@@ -1162,9 +1168,8 @@
      * on DBs that support it, rollback the transaction
      */
     public function rollback_sql() {
-        if (!parent::rollback_sql()) {
-            return false;
-        }
+        parent::rollback_sql();
+
         $sql = "ROLLBACK";
         $this->query_start($sql, NULL, SQL_QUERY_AUX);
         $result = pg_query($this->pgsql, $sql);
Index: lib/dml/oci_native_moodle_database.php
===================================================================
RCS file: /cvsroot/moodle/moodle/lib/dml/oci_native_moodle_database.php,v
retrieving revision 1.29
diff -u -r1.29 oci_native_moodle_database.php
--- lib/dml/oci_native_moodle_database.php	16 Oct 2009 14:14:03 -0000	1.29
+++ lib/dml/oci_native_moodle_database.php	22 Oct 2009 15:25:10 -0000
@@ -1528,9 +1528,12 @@
      * this is _very_ useful for massive updates
      */
     public function begin_sql() {
-        if (!parent::begin_sql()) {
-            return false;
+        parent::begin_sql();
+        if ($this->intransaction > 1) {
+            // do not start transactions in nested levels
+            return true;
         }
+
         $this->commit_status = OCI_DEFAULT; //Done! ;-)
         return true;
     }
@@ -1539,8 +1542,10 @@
      * on DBs that support it, commit the transaction
      */
     public function commit_sql() {
-        if (!parent::commit_sql()) {
-            return false;
+        parent::commit_sql();
+        if ($this->intransaction > 0) {
+            //nested transactions do not commit, only the top most one 
+            return true;
         }
 
         $this->query_start('--oracle_commit', NULL, SQL_QUERY_AUX);
@@ -1554,9 +1559,7 @@
      * on DBs that support it, rollback the transaction
      */
     public function rollback_sql() {
-        if (!parent::rollback_sql()) {
-            return false;
-        }
+        parent::rollback_sql();
 
         $this->query_start('--oracle_rollback', NULL, SQL_QUERY_AUX);
         $result = oci_rollback($this->oci);
Index: lib/dml/moodle_database.php
===================================================================
RCS file: /cvsroot/moodle/moodle/lib/dml/moodle_database.php,v
retrieving revision 1.104
diff -u -r1.104 moodle_database.php
--- lib/dml/moodle_database.php	9 Oct 2009 10:02:39 -0000	1.104
+++ lib/dml/moodle_database.php	22 Oct 2009 15:25:07 -0000
@@ -109,8 +109,8 @@
     /** @var bool true if db used for db sessions */
     protected $used_for_db_sessions = false;
 
-    /** @var bool Flag indicating transaction in progress */
-    protected $intransaction = false;
+    /** @var int Flag indicating transaction in progress and nesting level */
+    protected $intransaction = 0;
 
     /** @var int internal temporary variable */
     private $fix_sql_params_i;
@@ -281,7 +281,7 @@
      * Do NOT use connect() again, create a new instance if needed.
      */
     public function dispose() {
-        if ($this->intransaction) {
+        if ($this->intransaction > 0) {
             // unfortunately we can not access global $CFG any more and can not print debug
             error_log('Active database transaction detected when disposing database!');
         }
@@ -1879,54 +1879,57 @@
      * @return bool
      */
     function is_transaction_started() {
-        return $this->intransaction;
+        return ($this->intransaction > 0);
     }
 
     /**
-     * on DBs that support it, switch to transaction mode and begin a transaction
+     * On DBs that support it, switch to transaction mode and begin a transaction
      * you'll need to ensure you call commit_sql() or your changes *will* be lost.
+     * Multiple levels of transactions are supported, the rollback always propagates
+     * to the top most level via exceptions.
      *
      * this is _very_ useful for massive updates
      *
-     * Please note only one level of transactions is supported, please do not use
-     * transaction in moodle core! Transaction are intended for web services
-     * enrolment and auth synchronisation scripts, etc.
+     * Please do not use transaction in moodle core yet!
+     * Transaction are intended for web services, external API functions,
+     * enrolments, auth synchronisation scripts, etc.
      *
      * @return bool success
      */
     public function begin_sql() {
-        if ($this->intransaction) {
-            debugging('Transaction already in progress');
-            return false;
-        }
-        $this->intransaction = true;
-        return true;
+        $this->intransaction++;
+        return false;
     }
 
     /**
-     * on DBs that support it, commit the transaction
+     * On DBs that support it, commit the transaction,
+     * throws exception if transaction not in progress.
      * @return bool success
      */
     public function commit_sql() {
-        if (!$this->intransaction) {
-            debugging('Transaction not in progress');
-            return false;
+        if ($this->intransaction < 1) {
+            throw new coding_exception('DB transaction not in progress, can not commit');
         }
-        $this->intransaction = false;
-        return true;
+        $this->intransaction--;
+        return false;
     }
 
     /**
-     * on DBs that support it, rollback the transaction
+     * On DBs that support it, rollback the transaction,
+     * throws exception if requested in nested transaction
+     * because it needs to propagate to the top most level
+     * or the default_exception_handler(). 
      * @return bool success
      */
     public function rollback_sql() {
-        if (!$this->intransaction) {
-            debugging('Transaction not in progress');
-            return false;
+        if ($this->intransaction < 1) {
+            throw new coding_exception('DB transaction not in progress, can not rollback');
         }
-        $this->intransaction = false;
-        return true;
+        $this->intransaction--;
+        if ($this->intransaction > 0) {
+            throw new nested_rollback_exception();
+        }
+        return false;
     }
 
 /// session locking
Index: lib/dml/mssql_native_moodle_database.php
===================================================================
RCS file: /cvsroot/moodle/moodle/lib/dml/mssql_native_moodle_database.php,v
retrieving revision 1.12
diff -u -r1.12 mssql_native_moodle_database.php
--- lib/dml/mssql_native_moodle_database.php	16 Oct 2009 14:14:03 -0000	1.12
+++ lib/dml/mssql_native_moodle_database.php	22 Oct 2009 15:25:08 -0000
@@ -1205,9 +1205,12 @@
      * this is _very_ useful for massive updates
      */
     public function begin_sql() {
-        if (!parent::begin_sql()) {
-            return false;
+        parent::begin_sql();
+        if ($this->intransaction > 1) {
+            // do not start transactions in nested levels
+            return true;
         }
+
         $sql = "BEGIN TRANSACTION"; // Will be using READ COMMITTED isolation
         $this->query_start($sql, NULL, SQL_QUERY_AUX);
         $result = mssql_query($sql, $this->mssql);
@@ -1222,9 +1225,12 @@
      * on DBs that support it, commit the transaction
      */
     public function commit_sql() {
-        if (!parent::commit_sql()) {
-            return false;
+        parent::commit_sql();
+        if ($this->intransaction > 0) {
+            //nested transactions do not commit, only the top most one 
+            return true;
         }
+
         $sql = "COMMIT TRANSACTION";
         $this->query_start($sql, NULL, SQL_QUERY_AUX);
         $result = mssql_query($sql, $this->mssql);
@@ -1239,9 +1245,8 @@
      * on DBs that support it, rollback the transaction
      */
     public function rollback_sql() {
-        if (!parent::rollback_sql()) {
-            return false;
-        }
+        parent::rollback_sql();
+
         $sql = "ROLLBACK TRANSACTION";
         $this->query_start($sql, NULL, SQL_QUERY_AUX);
         $result = mssql_query($sql, $this->mssql);
Index: lib/dml/pdo_moodle_database.php
===================================================================
RCS file: /cvsroot/moodle/moodle/lib/dml/pdo_moodle_database.php,v
retrieving revision 1.21
diff -u -r1.21 pdo_moodle_database.php
--- lib/dml/pdo_moodle_database.php	8 Oct 2009 22:34:35 -0000	1.21
+++ lib/dml/pdo_moodle_database.php	22 Oct 2009 15:25:11 -0000
@@ -543,8 +543,10 @@
     }
 
     public function begin_sql() {
-        if (!parent::begin_sql()) {
-            return false;
+        parent::begin_sql();
+        if ($this->intransaction > 1) {
+            // do not start transactions in nested levels
+            return true;
         }
 
         $this->query_start('', NULL, SQL_QUERY_AUX);
@@ -559,9 +561,12 @@
         $this->query_end($result);
         return $result;
     }
+
     public function commit_sql() {
-        if (!parent::commit_sql()) {
-            return false;
+        parent::commit_sql();
+        if ($this->intransaction > 0) {
+            //nested transactions do not commit, only the top most one 
+            return true;
         }
 
         $this->query_start('', NULL, SQL_QUERY_AUX);
@@ -578,9 +583,7 @@
     }
 
     public function rollback_sql() {
-        if (!parent::rollback_sql()) {
-            return false;
-        }
+        parent::rollback_sql();
 
         $this->query_start('', NULL, SQL_QUERY_AUX);
         $result = true;
Index: lib/dml/mysqli_native_moodle_database.php
===================================================================
RCS file: /cvsroot/moodle/moodle/lib/dml/mysqli_native_moodle_database.php,v
retrieving revision 1.44
diff -u -r1.44 mysqli_native_moodle_database.php
--- lib/dml/mysqli_native_moodle_database.php	8 Oct 2009 22:34:35 -0000	1.44
+++ lib/dml/mysqli_native_moodle_database.php	22 Oct 2009 15:25:09 -0000
@@ -1028,6 +1028,12 @@
      * this is _very_ useful for massive updates
      */
     public function begin_sql() {
+        parent::begin_sql();
+        if ($this->intransaction > 1) {
+            // do not start transactions in nested levels
+            return true;
+        }
+
         // Only will accept transactions if using InnoDB storage engine (more engines can be added easily BDB, Falcon...)
         $sql = "SELECT @@storage_engine";
         $this->query_start($sql, NULL, SQL_QUERY_AUX);
@@ -1042,10 +1048,6 @@
         }
         $result->close();
 
-        if (!parent::begin_sql()) {
-            return false;
-        }
-
         $sql = "SET SESSION TRANSACTION ISOLATION LEVEL READ COMMITTED";
         $this->query_start($sql, NULL, SQL_QUERY_AUX);
         $result = $this->mysqli->query($sql);
@@ -1063,9 +1065,12 @@
      * on DBs that support it, commit the transaction
      */
     public function commit_sql() {
-        if (!parent::commit_sql()) {
-            return false;
+        parent::commit_sql();
+        if ($this->intransaction > 0) {
+            //nested transactions do not commit, only the top most one 
+            return true;
         }
+
         $sql = "COMMIT";
         $this->query_start($sql, NULL, SQL_QUERY_AUX);
         $result = $this->mysqli->query($sql);
@@ -1078,9 +1083,8 @@
      * on DBs that support it, rollback the transaction
      */
     public function rollback_sql() {
-        if (!parent::rollback_sql()) {
-            return false;
-        }
+        parent::rollback_sql();
+
         $sql = "ROLLBACK";
         $this->query_start($sql, NULL, SQL_QUERY_AUX);
         $result = $this->mysqli->query($sql);
Index: lib/setuplib.php
===================================================================
RCS file: /cvsroot/moodle/moodle/lib/setuplib.php,v
retrieving revision 1.78
diff -u -r1.78 setuplib.php
--- lib/setuplib.php	15 Oct 2009 22:34:34 -0000	1.78
+++ lib/setuplib.php	22 Oct 2009 15:25:06 -0000
@@ -173,10 +173,13 @@
     // detect active db transactions, rollback and log as error
     if ($DB && $DB->is_transaction_started()) {
         error_log('Database transaction aborted by exception in ' . $CFG->dirroot . $SCRIPT);
-        try {
-            // note: transaction blocks should never change current $_SESSION
-            $DB->rollback_sql();
-        } catch (Exception $ignored) {
+        while($DB->is_transaction_started()) {
+            //nested transactions throw exceptions, we need to traverse to the top level exception
+            try {
+                // note: transaction blocks should never change current $_SESSION
+                $DB->rollback_sql();
+            } catch (Exception $ignored) {
+            }
         }
     }
 
Index: lib/dmllib.php
===================================================================
RCS file: /cvsroot/moodle/moodle/lib/dmllib.php,v
retrieving revision 1.183
diff -u -r1.183 dmllib.php
--- lib/dmllib.php	8 Oct 2009 22:25:28 -0000	1.183
+++ lib/dmllib.php	22 Oct 2009 15:25:05 -0000
@@ -63,6 +63,17 @@
 }
 
 /**
+ * Indicates nested transaction tried to rollback,
+ * we need to propage this request to the top most transaction
+ * instead or to the default_exception_handler().
+ */
+class nested_rollback_exception extends dml_exception {
+    function __construct() {
+        parent::__construct('dmlnestedrollback');
+    }
+}
+
+/**
  * DML db connection exception - triggered if database not accessible.
  */
 class dml_connection_exception extends dml_exception {
Index: lang/en_utf8/error.php
===================================================================
RCS file: /cvsroot/moodle/moodle/lang/en_utf8/error.php,v
retrieving revision 1.207
diff -u -r1.207 error.php
--- lang/en_utf8/error.php	5 Oct 2009 17:45:02 -0000	1.207
+++ lang/en_utf8/error.php	22 Oct 2009 15:25:05 -0000
@@ -178,6 +178,7 @@
 $string['ddltablenotexist'] = 'Table \"$a\" does not exist';
 $string['ddlunknownerror'] = 'Unknown DDL library error';
 $string['ddlxmlfileerror'] = 'XML database file errors found';
+$string['dmlnestedrollback'] = 'Nested transaction rollback exception';
 $string['dmlreadexception'] = 'Error reading from database';
 $string['dmlwriteexception'] = 'Error writing to database';
 $string['destinationcmnotexit'] = 'The destination course module does not exist';