public void UpdateCreditScoreForAllUsers()
{
/*
* Demo of DbContextScope + parallel programming.
*/
using (var dbContextScope = _dbContextScopeFactory.Create())
{
//-- Get all users
var dbContext = dbContextScope.DbContexts.Get <UserManagementDbContext>();
var userIds = dbContext.Users.Select(u => u.Id).ToList();
Console.WriteLine("Found {0} users in the database. Will calculate and store their credit scores in parallel.", userIds.Count);
//-- Calculate and store the credit score of each user
// We're going to imagine that calculating a credit score of a user takes some time.
// So we'll do it in parallel.
// You MUST call SuppressAmbientContext() when kicking off a parallel execution flow
// within a DbContextScope. Otherwise, this DbContextScope will remain the ambient scope
// in the parallel flows of execution, potentially leading to multiple threads
// accessing the same DbContext instance.
using (_dbContextScopeFactory.SuppressAmbientContext())
{
Parallel.ForEach(userIds, UpdateCreditScore);
}
// Note: SaveChanges() isn't going to do anything in this instance since all the changes
// were actually made and saved in separate DbContextScopes created in separate threads.
dbContextScope.SaveChanges();
}
}