CODEWITHSUNDEEP
c#entity-frameworkenterprise-libraryazure-sql-database
Dusda
Dusda

Reputation: 3367

RetryPolicy in Enterprise Library 5 does not work

I am working on a small app to translate and import a large amount of data from one database to another. To do this, I'm using Entity Framework and some custom extensions to commit a page of items at a time, in batches of 1000 or so. Since this can take a while, I was also interested in making sure the whole thing wouldn't grind to a halt if there is a hiccup in the connection while it's running.

I chose the Transient Fault Handling Application block, part of Enterprise Library 5.0, following this article (see Case 2: Retry Policy With Transaction Scope). Here is an example of my implementation in the form of an ObjectContext extension, which simply adds objects to the context and tries to save them, using a Retry Policy focused on Sql Azure stuff:

public static void AddObjectsAndSave<T>(this ObjectContext context, IEnumerable<T> objects)
    where T : EntityObject
{
    if(!objects.Any())
        return;

    var policy = new RetryPolicy<SqlAzureTransientErrorDetectionStrategy>
        (10, TimeSpan.FromSeconds(10));
    var tso = new TransactionOptions();
    tso.IsolationLevel = IsolationLevel.ReadCommitted;

    var name = context.GetTableName<T>();

    foreach(var item in objects)
        context.AddObject(name, item);


    policy.ExecuteAction(() =>
    {
        using(TransactionScope ts = new TransactionScope(TransactionScopeOption.Required, tso))
        {
            context.SaveChanges();

            ts.Complete();
        }
    });
}

The code works great, until I actually test the Retry Policy by pausing my local instance of Sql Server while it's running. It almost immediately poops, which is odd. You can see that I've got the policy configured to try again in ten second intervals; either it is ignoring the interval or failing to catch the error. I suspect the latter, but I'm new to this so I don't really know.

Upvotes: 0

Views: 1089

Answers (1)

Herve Roggero
Herve Roggero

Reputation: 5249

I suspect that the SqlAzureTransientErrorDetectionStrategy does not include the error your are simulating. This policy implements specific errors thrown by SQL Azure. Look at this code to find out which errors are implemented by this policy: http://code.msdn.microsoft.com/Reliable-Retry-Aware-BCP-a5ae8e40/sourcecode?fileId=22213&pathId=1098196556

To handle the error you are trying to catch, you could implement your own strategy by implementing the ITransientErrorDetectionStrategy interface.

Upvotes: 2

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