Add support for transaction multiplexing

Also delay getting a connection until after we do all the sanity
checks (e.g., that there is no active transaction). Otherwise we
are running risk of getting blocked rather than throwing an
exception.

1 files changed, 1 insertions, 5 deletions

diff --git a/odb/tracer/connection.cxx b/odb/tracer/connection.cxx
index 516e36a..54c233c 100644
--- a/odb/tracer/connection.cxx
+++ b/odb/tracer/connection.cxx
@@ -27,11 +27,7 @@ namespace odb
     transaction_impl* connection::
     begin ()
     {
-      if (odb::transaction::has_current ())
-        throw already_in_transaction ();
-
-      return new transaction_impl (
-        connection_ptr (inc_ref (this)));
+      return new transaction_impl (connection_ptr (inc_ref (this)));
     }
   }
 }