I am using SQLCipher for sqlite DB encryption in WPF application. As per knowledge they recommend to use Singleton pattern for my DbContext class ensure a single instance is used throughout my application for better performance.
Below is a simplified version of the code:
public class MyDbContext : DbContext
{
private static MyDbContext _instance;
private MyDbContext() : base("MyConnectionString") { }
public static MyDbContext Instance
{
get
{
if (_instance == null)
{
_instance = new MyDbContext();
}
return _instance;
}
}
}
For delete, update, and insert operations, I begin a transaction and perform the operations. However, I sometimes perform save and update operations from a separate thread. The problem occurs when one thread is performing an update operation and the main thread attempts to read data from the database at the same time. This causes the following exception:
Error occurred while reading from the store provider's data reader. See the inner exception for details.
---> System.InvalidOperationException: Connection was closed, statement was terminated
at System.Data.SQLite.SQLiteDataReader.CheckClosed()
at System.Data.SQLite.SQLiteDataReader.PrivateRead(Boolean ignoreSingleRow)
at System.Data.SQLite.SQLiteDataReader.Read()
My questions are:
- how to avoid such errors gracefully?
- Shall the implementation of retry logic when getting the exception with delay be appropriate?
- Any other solution suggestion.
Any help or guidance would be appreciated!
DbContextis meant to be a short-lived unit-of-work object that is not shared between threads. A singletonDbContextis incorrect, plain-and-simple. (EF6 and EFCore are identical in this respect, btw).