I would like to do a check-then-update in an atomic operation. I am using dbcontext to manage the transaction. I was expecting to get an exception if the record has been modified by another thread but no exception is thrown. Any help would be appreciated. Here's my output:
Thread-4: Reading...
Thread-5: Reading...
Thread-5: Updating destination 1
Thread-4: Updating destination 1
Thread-4: SaveChanges
Thread-5: SaveChanges
Here's my code snippet:
public static void Main(string[] args)
{
PopulateData();
(new Thread(UpdateDestination1)).Start();
(new Thread(UpdateDestination1)).Start();
}
public static void UpdateDestination1()
{
using (var context1 = new BreakAwayContext())
{
Console.WriteLine("Thread-{0}: Reading...", Thread.CurrentThread.ManagedThreadId);
var d = context1.Destinations.FirstOrDefault();
Console.WriteLine("Thread-{0}: Updating destination {1}", Thread.CurrentThread.ManagedThreadId, d.DestinationId);
d.Name = "Thread-" + Thread.CurrentThread.ManagedThreadId;
try
{
context1.SaveChanges();
Console.WriteLine("Thread-{0}: SaveChanges", Thread.CurrentThread.ManagedThreadId);
}
catch (OptimisticConcurrencyException)
{
Console.WriteLine("OptimisticConcurrencyException!!!");
throw;
}
}
}
You can use ConcurrencyCheck annotation on a property ( http://msdn.microsoft.com/en-us/data/gg193958.aspx ) or IsConcurrencyToken() or .IsRowversion when configuring a property with fluent API ( http://msdn.microsoft.com/en-us/data/jj591617#1.12). Typically you would have a rowversion column in the database.
来源:https://stackoverflow.com/questions/13061034/how-to-enable-concurrency-checking-using-ef-5-0-code-first