MvcMiniProfiler and NHibernate: Take 2 - Batching support

Jul 27

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MvcMiniProfiler and NHibernate: Take 2 - Batching support

[UPDATE: Thanks to Sam for the comment - data reader now intercepted and wrapped, gist updated]

My previous solution for getting NHibernate working with MvcMiniProfiler had one problem, it didn't work with batching.

RealProxy was mentioned as a possible solution in the issues forum - see http://code.google.com/p/mvc-mini-profiler/issues/detail?id=29&can=1

The following code should be viewed as experimental, I have never used RealProxy before and I may be doing something really dumb here - however this is working well in my application and profiling now works with batching.

The solution is similar to before, I'm creating a new NHibernate client driver. However this time I'm not using any of the existing profiled wrapper classes. I'm creating a transparent proxy for SqlCommand, intercepting calls to ExecuteNonQuery/ExecuteReader/ExecuteScalar and making calls to the IDbProfiler.

Here's the gist, comments appreciated -

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7 months ago sam responded:

I have done this before a few years back and it worked just fine, there are some caveats though. (I used this trick in http://www.symantec.com/connect/articles/getting-started-altiris-profiler-tro... )

You may also be interested in optionally intercepting the reader, that way you can get the full duration of the sql involved (eg. exec command, wait a sec, iterate through results)

Also be sure to look at the eventing in profiler around readers, it is a bit more granular

7 months ago Scott Kirkland responded:

This is a pretty cool solution and it works well for me on reads/queries, but for any updates/inserts it fails with the old "unable to cast to sqlCommand" error. When I disable NHibernate batching support it works well, but with batching I cannot seem to make any updates. I copied the stack trace into a gist in the hopes that it might help: https://gist.github.com/1120805. Please let me know if you need any more info. Thanks, and keep up the great work, I'd love to use this in my projects.

Scott

7 months ago Robert Milne responded:

@Scott this is a slightly different error to the original problem - if you search google for "Unable to cast transparent proxy to type" most of the results seem to be related to loading Assemblies across AppDomains, however I can't think how this would apply to the DbCommandProxy.

Can I ask what versions of NHibernate and .net are you using?

7 months ago Scott Kirkland responded:

@Robert- I'm using NHibernate 3.1 and .NET 4.0 in an MVC3 project. I'm only working within a single AppDomain. To test I tried to pick the simplest entity to update/save in order to get the problem narrowed down to when batching is enabled. If batched saves is working for you, I can try to create a small sample project to repo the issue, though I'm not sure why that would be the case.

7 months ago Robert Milne responded:

@Scott very strange - I've confirmed that batching works with two separate projects, one was NH3.0 (Fluent Configuration) .NET4 MVC2 - the other was NH3.2 (loquacious configuration) .NET4 MVC3.

I can't think why the transparent proxy would be failing this way. If you can create a small sample that reproduces this I'd be happy to take a look.

In the meantime I'll check the source for NHibernate 3.1 just in case the ClientDriver code is doing something different.

7 months ago Scott Kirkland responded:

@Robert -- I reproduced the problem in a small sample project which I pushed to GitHub at https://github.com/srkirkland/NHibernateMiniProfilerIntegration. All I did was create a new Mvc3 project, download the nuget packages for Fluent Nhibernate (w/ NH3.1) and the profiler, and then create a quick Order entity based off of Northwind. Really all of the interesting code is in the HomeController which is available at this gist: https://gist.github.com/1121446. The problem comes when batching is enabled and you try to get and entity, change some property, and save. The one change I had to make was to modify the base class of your code from Sql2008ClientDriver to SqlClientDriver because the former does not exist in NHibernate3.1. Thanks for any help you can give, and btw my twitter is @srkirkland if you have questions.

7 months ago Robert Milne responded:

Thanks for the example Scott, I've replicated this on my PC - I also went back and discovered that the NH3.0 project I previously thought was working ... had batching disabled ...

So at the moment this looks like it's only working with 3.2 - however I've been through the NH source code and I can't see any significant changes to the Client Driver or the batching code that would explain this - I'm wondering if Fluent NHibernate could be the factor here.

I want to get this working with our existing 3.0 project so I'll keep digging and let you know if I find anything

7 months ago Robert Milne responded:

I'm close to admitting defeat for earlier versions of NHibernate I'm sad to say.

I switched the transparent proxy from DbCommand to SqlCommand and got a more meaninful error message -

Remoting cannot find field 'ObjectID' on type 'System.Data.SqlClient.SqlCommand

(ObjectID is an internal field which is why it's not working)

I tried to intercept the call to "FieldGetter" and used reflection on our real instance to get this value - this seemed to return the correct values, and I believe I was returning the results correctly, however these commands were never executed in the batch.

When using NHibernate 3.2, the SqlCommand proxy does not attempt to access the internal ObjectID - I'm at a loss to explain why this is different.

6 months ago nick responded:

I had to make some changes to SqlClientBatchingBatcher to get this to work in NHibernate 3.2 GA.

In AddToBatch at line 72, add the following, which just creates a cloned but non-proxy SqlCommand and uses that. Works for me!

if (batchUpdate is System.Data.SqlClient.SqlCommand)
currentBatch.Append((System.Data.SqlClient.SqlCommand) batchUpdate);
else
{
var sqlCommand = new System.Data.SqlClient.SqlCommand(
batchUpdate.CommandText,
(SqlConnection)batchUpdate.Connection,
(SqlTransaction)batchUpdate.Transaction);
foreach (SqlParameter p in batchUpdate.Parameters)
{
sqlCommand.Parameters.Add(
new SqlParameter(
p.ParameterName,
p.SqlDbType,
p.Size,
p.Direction,
p.IsNullable,
p.Precision,
p.Scale,
p.SourceColumn,
p.SourceVersion,
p.Value));
}
currentBatch.Append(sqlCommand);
}

6 months ago gedgei responded:

Hi,
you say that this solution works with batching in NHibernate 3.2, but I can't seem to get it to work? Proxying both, DbCommand or SqlCommand, produce the same exceptions as written by people who commented above.

Testing with NHibernate 3.2GA.

Any thought?

Thanks.

6 months ago mcintyre321 (Twitter) responded:

Hi I've just taken Nicks fix and put it into a partial class file you can use to fix the Cast error without having to recompile NH.

http://www.adverseconditionals.com/2011/08/fixing-miniprofiler-with-nhibernat...

6 months ago Robert Milne responded:

Thanks to Nick and Harry for updates - I'd really hoped to avoid having to either re-compile NHibernate or duplicate large chunks from the NHibernate source (which might be version specific and will need to be maintained with future updates).

Using Harry's batcher I wonder if it might be possible to replace RealProxy with the original ProfiledDbCommand - will have to investigate :)

6 months ago mcintyre321 (Twitter) responded:

Well I did take a couple of classes out of the NHibernate source so it might need some maintenance at some point...

6 months ago Robert Milne responded:

some updates http://blog.fearofaflatplanet.me.uk/mvcminiprofiler-and-nhibernate-take-3

Fear of a Flat Planet

It's all downhill from here...

MvcMiniProfiler and NHibernate: Take 2 - Batching support

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