Highligting New Functionality That Has Become Available Due to the New 'Multiple DB Connections for Multiple Threads' Feature

christiankatict

Hi fellow developers,

There are a few new features that were introduced with the new 'Multiple DB Connections for Multiple Threads' Feature that I want to highlight here (apart from the main feature, of course: OpenPetra can now work with multiple DB Connections in multiple Threads!):

Although a huge effort was made to make sure that the introduction of the 'Multiple DB Connections for Multiple Threads' Feature is a non-breaking change that change also deliberately introduces new Typed Exceptions that are designed to bring violations of 'thread-safe DB access rules' to the light that exist in our code base! Existing program code sections that may apparently have 'run fine' previously will from now on no longer work when they break such rules! Should that happen then we will need to fix such program code. For details on this see: https://wiki.openpetra.org/index.php/Working_with_multiple_DB_Connections#Automatic:Multi-threading_and_multi-connection.27Sanity_Checks.27_in_the_TDataBase_Class
Naming DB Connections and DB Transactions: Whenever new DB Connections gets established and whenever new DB Transactions are started it is now possible to optionally supply a 'speaking name' for those. You are strongly encouraged to do so! (All places in source code where new DB Connections get established already got changed by me to specify such names). These names are very helpful when debbugging multi-threading and multi-DB-connections issues. For details on this see https://wiki.openpetra.org/index.php/Working_with_multiple_DB_Connections#Verbose_Logging
The new overloaded DBAccess.GetDBAccessObj(...) Method acts as a 'set of points' (using figurative railway language here) and will yield the 'globally available' DBAccess.GDBAccessObj in case a null value for the ATransaction gets passed, otherwise it will yield the TDataBase instance which started the DB Transaction that got passed in in its TDBTransaction ATransaction Argument. This makes it very easy to change existing Methods to use either the 'globally available' DB Connection or a separate DB connection, and it can be used in newly written Methods, too. For details see https://wiki.openpetra.org/index.php/Working_with_multiple_DB_Connections#Changing_.28Library.29_Methods_so_That_They_Can_Work_With_the_Default_DB_Connection_or_a_Separate_DB_Connection
Utilising our Typed DataStore Methods and all auto-generated DB Access Methods with separate DB Connections: https://wiki.openpetra.org/index.php/Working_with_multiple_DB_Connections#Using_Methods_of_our_TTypedDataAccess_Class_and_Auto-generated_.27Typed_DataStore.27_Methods_With_Separate_DB_Connections
I have written up a few FAQ's which should answer many of your questions: https://wiki.openpetra.org/index.php/Working_with_multiple_DB_Connections#FAQ.27s

Kind regards,

ChristianK