Allow stacking of transactions

Closes #1166

diff --git a/wcfsetup/install/files/lib/system/database/Database.class.php b/wcfsetup/install/files/lib/system/database/Database.class.php
index 4228b8472ca9d46f46531b74a419bf65f91536ac..4234cac5346cd44dc6bd5845387e6dcc8367bc4c 100644 (file)
--- a/wcfsetup/install/files/lib/system/database/Database.class.php
+++ b/wcfsetup/install/files/lib/system/database/Database.class.php
@@ -1,5 +1,7 @@
 <?php
 namespace wcf\system\database;
+use wcf\system\benchmark\Benchmark;
+use wcf\system\WCF;
 
 /**
  * Abstract implementation of a database access class using PDO.
@@ -73,10 +75,10 @@ abstract class Database {
        protected $pdo = null;
        
        /**
-        * Indicates if there is an open transaction.
-        * @var boolean
+        * amount of active transactions
+        * @var integer
         */
-       protected $hasActiveTransaction = false;
+       protected $activeTransactions = 0;
        
        /**
         * Creates a Dabatase Object.
@@ -115,7 +117,7 @@ abstract class Database {
                        return $this->pdo->lastInsertId();
                }
                catch (\PDOException $e) {
-                       throw new DatabaseException("Can not fetch last insert id", $this);
+                       throw new DatabaseException("Cannot fetch last insert id", $this);
                }
        }
        
@@ -126,16 +128,22 @@ abstract class Database {
         */
        public function beginTransaction() {
                try {
-                       if ($this->hasActiveTransaction) {
-                               return false;
+                       if ($this->activeTransactions === 0) {
+                               if (WCF::benchmarkIsEnabled()) Benchmark::getInstance()->start("BEGIN", Benchmark::TYPE_SQL_QUERY);
+                               $result = $this->pdo->beginTransaction();
                        }
                        else {
-                               $this->hasActiveTransaction = $this->pdo->beginTransaction();
-                               return $this->hasActiveTransaction;
+                               if (WCF::benchmarkIsEnabled()) Benchmark::getInstance()->start("SAVEPOINT level".$this->activeTransactions, Benchmark::TYPE_SQL_QUERY);
+                               $result = $this->pdo->exec("SAVEPOINT level".$this->activeTransactions) !== false;
                        }
+                       if (WCF::benchmarkIsEnabled()) Benchmark::getInstance()->stop();
+                       
+                       $this->activeTransactions++;
+                       
+                       return $result;
                }
                catch (\PDOException $e) {
-                       return false;
+                       throw new DatabaseException("Cannot begin transaction", $this);
                }
        }
        
@@ -146,11 +154,23 @@ abstract class Database {
         */
        public function commitTransaction() {
                try {
-                       $this->hasActiveTransaction = false;
-                       return $this->pdo->commit();
+                       $this->activeTransactions--;
+                       
+                       if ($this->activeTransactions === 0) {
+                               if (WCF::benchmarkIsEnabled()) Benchmark::getInstance()->start("COMMIT", Benchmark::TYPE_SQL_QUERY);
+                               $result = $this->pdo->commit();
+                       }
+                       else {
+                               if (WCF::benchmarkIsEnabled()) Benchmark::getInstance()->start("RELEASE SAVEPOINT level".$this->activeTransactions, Benchmark::TYPE_SQL_QUERY);
+                               $result = $this->pdo->exec("RELEASE SAVEPOINT level".$this->activeTransactions) !== false;
+                       }
+                       
+                       if (WCF::benchmarkIsEnabled()) Benchmark::getInstance()->stop();
+                       
+                       return $result;
                }
                catch (\PDOException $e) {
-                       return false;
+                       throw new DatabaseException("Cannot commit transaction", $this);
                }
        }
        
@@ -161,11 +181,23 @@ abstract class Database {
         */
        public function rollBackTransaction() {
                try {
-                       $this->hasActiveTransaction = false;
-                       return $this->pdo->rollBack();
+                       $this->activeTransactions--;
+                       
+                       if ($this->activeTransactions === 0) {
+                               if (WCF::benchmarkIsEnabled()) Benchmark::getInstance()->start("ROLLBACK", Benchmark::TYPE_SQL_QUERY);
+                               $result = $this->pdo->rollback();
+                       }
+                       else {
+                               if (WCF::benchmarkIsEnabled()) Benchmark::getInstance()->start("ROLLBACK TO SAVEPOINT level".$this->activeTransactions, Benchmark::TYPE_SQL_QUERY);
+                               $result = $this->pdo->exec("ROLLBACK TO SAVEPOINT level".$this->activeTransactions) !== false;
+                       }
+                       
+                       if (WCF::benchmarkIsEnabled()) Benchmark::getInstance()->stop();
+                       
+                       return $result;
                }
                catch (\PDOException $e) {
-                       return false;
+                       throw new DatabaseException("Cannot rollback transaction", $this);
                }
        }
        
@@ -185,10 +217,10 @@ abstract class Database {
                        if ($pdoStatement instanceof \PDOStatement) {
                                return new $this->preparedStatementClassName($this, $pdoStatement, $statement);
                        }
-                       throw new DatabaseException("Can not prepare statement: ".$statement, $this);
+                       throw new DatabaseException("Cannot prepare statement: ".$statement, $this);
                }
                catch (\PDOException $e) {
-                       throw new DatabaseException("Can not prepare statement: ".$statement, $this);
+                       throw new DatabaseException("Cannot prepare statement: ".$statement, $this);
                }
        }