SPI_commit — commit the current transaction
void SPI_commit(void)
   SPI_commit commits the current transaction.  It is
   approximately equivalent to running the SQL
   command COMMIT.  After the transaction is committed, a
   new transaction is automatically started using default transaction
   characteristics, so that the caller can continue using SPI facilities.
   If there is a failure during commit, the current transaction is instead
   rolled back and a new transaction is started, after which the error is
   thrown in the usual way.
  
   This function can only be executed if the SPI connection has been set as
   nonatomic in the call to SPI_connect_ext.