mysql: Implement transaction handling

src/libstrongswan/plugins/mysql/mysql_database.c

@@ -50,6 +50,11 @@ struct private_mysql_database_t {
 	 */
 	linked_list_t *pool;
 
+	/**
+	 * thread-specific transaction, as transaction_t
+	 */
+	thread_value_t *transaction;
+
 	/**
 	 * mutex to lock pool
 	 */
@@ -99,6 +104,28 @@ struct conn_t {
 	bool in_use;
 };
 
+/**
+ * database transaction
+ */
+typedef struct {
+
+	/**
+	 * Reference to the specific connection we started the transaction on
+	 */
+	conn_t *conn;
+
+	/**
+	 * Refcounter if transaction() is called multiple times
+	 */
+	refcount_t refs;
+
+	/**
+	 * TRUE if transaction was rolled back
+	 */
+	bool rollback;
+
+} transaction_t;
+
 /**
  * Release a mysql connection
  */
@@ -109,6 +136,16 @@ static void conn_release(private_mysql_database_t *this, conn_t *conn)
 	this->mutex->unlock(this->mutex);
 }
 
+/**
+ * Destroy a transaction and release the connection
+ */
+static void transaction_destroy(private_mysql_database_t *this,
+								transaction_t *trans)
+{
+	conn_release(this, trans->conn);
+	free(trans);
+}
+
 /**
  * thread specific initialization flag
  */
@@ -161,13 +198,24 @@ static void conn_destroy(conn_t *this)
 /**
  * Acquire/Reuse a mysql connection
  */
-static conn_t *conn_get(private_mysql_database_t *this)
+static conn_t *conn_get(private_mysql_database_t *this, transaction_t **trans)
 {
 	conn_t *current, *found = NULL;
 	enumerator_t *enumerator;
+	transaction_t *transaction;
 
 	thread_initialize();
 
+	transaction = this->transaction->get(this->transaction);
+	if (transaction)
+	{
+		if (trans)
+		{
+			*trans = transaction;
+		}
+		return transaction->conn;
+	}
+
 	while (TRUE)
 	{
 		this->mutex->lock(this->mutex);
@@ -490,7 +538,7 @@ METHOD(database_t, query, enumerator_t*,
 	mysql_enumerator_t *enumerator = NULL;
 	conn_t *conn;
 
-	conn = conn_get(this);
+	conn = conn_get(this, NULL);
 	if (!conn)
 	{
 		return NULL;
@@ -582,7 +630,7 @@ METHOD(database_t, execute, int,
 	conn_t *conn;
 	int affected = -1;
 
-	conn = conn_get(this);
+	conn = conn_get(this, NULL);
 	if (!conn)
 	{
 		return -1;
@@ -606,19 +654,81 @@ METHOD(database_t, execute, int,
 METHOD(database_t, transaction, bool,
 	private_mysql_database_t *this)
 {
-	return FALSE;
+	transaction_t *trans = NULL;
+	conn_t *conn;
+
+	conn = conn_get(this, &trans);
+	if (!conn)
+	{
+		return FALSE;
+	}
+	else if (trans)
+	{
+		ref_get(&trans->refs);
+		return TRUE;
+	}
+	/* these statements are not supported in prepared statements that are used
+	 * by the execute() method */
+	if (mysql_query(conn->mysql, "START TRANSACTION") != 0)
+	{
+		DBG1(DBG_LIB, "starting transaction failed: %s",
+			 mysql_error(conn->mysql));
+		conn_release(this, conn);
+		return FALSE;
+	}
+	INIT(trans,
+		.conn = conn,
+		.refs = 1,
+	);
+	this->transaction->set(this->transaction, trans);
+	return TRUE;
+}
+
+/**
+ * Finalize a transaction depending on the reference count and if it should be
+ * rolled back.
+ */
+static bool finalize_transaction(private_mysql_database_t *this,
+								 bool rollback)
+{
+	transaction_t *trans;
+	char *command = "COMMIT";
+	bool success;
+
+	trans = this->transaction->get(this->transaction);
+	if (!trans)
+	{
+		DBG1(DBG_LIB, "no database transaction found");
+		return FALSE;
+	}
+	/* set flag, can't be unset */
+	trans->rollback |= rollback;
+
+	if (ref_put(&trans->refs))
+	{
+		if (trans->rollback)
+		{
+			command = "ROLLBACK";
+		}
+		success = mysql_query(trans->conn->mysql, command) == 0;
+
+		this->transaction->set(this->transaction, NULL);
+		transaction_destroy(this, trans);
+		return success;
+	}
+	return TRUE;
 }
 
 METHOD(database_t, commit, bool,
 	private_mysql_database_t *this)
 {
-	return FALSE;
+	return finalize_transaction(this, FALSE);
 }
 
 METHOD(database_t, rollback, bool,
 	private_mysql_database_t *this)
 {
-	return FALSE;
+	return finalize_transaction(this, TRUE);
 }
 
 METHOD(database_t, get_driver,db_driver_t,
@@ -630,6 +740,7 @@ METHOD(database_t, get_driver,db_driver_t,
 METHOD(database_t, destroy, void,
 	private_mysql_database_t *this)
 {
+	this->transaction->destroy(this->transaction);
 	this->pool->destroy_function(this->pool, (void*)conn_destroy);
 	this->mutex->destroy(this->mutex);
 	free(this->host);
@@ -721,9 +832,10 @@ mysql_database_t *mysql_database_create(char *uri)
 	}
 	this->mutex = mutex_create(MUTEX_TYPE_DEFAULT);
 	this->pool = linked_list_create();
+	this->transaction = thread_value_create(NULL);
 
 	/* check connectivity */
-	conn = conn_get(this);
+	conn = conn_get(this, NULL);
 	if (!conn)
 	{
 		destroy(this);