Category: Technical Tips

I have spent too long today trying to track down an intermittent “SQLite Error 5: ‘database is locked’” error in .Net Core Entity Framework.

I have read plenty of documentation and even tried swapping to use SQL Server, as opposed to SQLite, but this just resulted in the error ‘There is already an open DataReader associated with this Connection which must be closed first.’.

So everything pointed to it being a mistake I had made.

And it was, it turns out the issue was I had the dbContext.SaveChanges() call inside a foreach loop

It was

using (var dbContext = scope.ServiceProvider.GetRequiredService()) {
    var itemsToQueue = dbContext.CopyOperations.Where(o => o.RequestedStartTime < DateTime.UtcNow && o.Status == OperationStatus.Queued);
    foreach (var item in itemsToQueue) {
        item.Status = OperationStatus.StartRequested;
        item.StartTime = DateTime.UtcNow;
        dbContext.SaveChanges();
    }
}

And it should have been

 using (var dbContext = scope.ServiceProvider.GetRequiredService()) {
    var itemsToQueue = dbContext.CopyOperations.Where(o => o.RequestedStartTime < DateTime.UtcNow && o.Status == OperationStatus.Queued);
    foreach (var item in itemsToQueue) {
        item.Status = OperationStatus.StartRequested;
        item.StartTime = DateTime.UtcNow;
    }
    dbContext.SaveChanges();
}

Once this change was made my error disappeared.

There are good reasons why you might wish to move an existing Azure DevOps organisation from one region to another. The most common ones are probably:

• A new Azure DevOps region has become available since you created your organisation that is a ‘better home’ for your projects.
• New or changing national regulations require your source stored in a specific location.
• You want your repositories as close to your workers as possible, to reduce network latency.

One of these reasons meant I recently had to move an Azure DevOps organisation, so followed the documented process. This requires you to

1. Whilst logged in as the Azure DevOps organisation owner, open the Azure DevOps Virtual Support Agent
2. Select the quick action ‘Change Organization Region’
3. Follow the wizard to pick the new region and the date for the move.

You are warned that there could be a short loss of service during the move. Much of the move is done as a background process. It is only the final switch over that can interrupt service, hence this interruption being short.

I followed this process, but after the planned move date I found my organisation has not moved. In the Virtual Support Agent, I found the message.

Please note that region move requests are currently delayed due to ongoing deployments. We may not be able to perform the change at your requested time and may ask you to reschedule. We apologize for the potential delay and appreciate your patience!

I received no other emails, I suspect overly aggressive spam filters were the cause of that, but it meant I was unclear what to do next. Should I:

1. Just wait i.e. do not reschedule anything, even though the target date is now in the past
2. Reschedule the existing move request to a date in the future using the virtual assistant wizard
3. Cancel the old request and start the process again from scratch

After asking the question in the Visual Studio Developer Community Forums I was told the correct action is to cancel the old request and request a new move date. It seems that once your requested date is passed the move will not take place no matter how long you wait.

Hence, I created a new request, which all went through exactly as planned.

I was reminded recently of the hoops you have to jump through to run UWP unit tests within an Azure DevOps automated build.

The key steps you need to remember are as follows

Desktop Interaction

The build agent should not be running as a service it must be able to interact with the desktop.

If you did not set this mode during configuration this post from Donovan Brown shows how to swap the agent over without a complete reconfiguration.

Test Assemblies

The UWP unit test projects are not built as a DLL, but as an EXE.

I stupidly just made my VSTest task look for the generated EXE and run the tests they contained. This does not work generating the somewhat confusing error

Test run will use DLL(s) built for framework .NETFramework,Version=v4.0 and platform X86. Following DLL(s) do not match framework/platform settings.
BlackMarble.Spectrum.FridgeManagement.Client.OneWire.UnitTests.exe is built for Framework .NETCore,Version=v5.0 and Platform X86.

What you should search for as the entry point for the tests is the .appxrecipe file. Once tI used this my tests ran.

So my pipeline YML to run all the tests in a built solutions was

- task: VisualStudioTestPlatformInstaller@1
   inputs:
      packageFeedSelector: 'nugetOrg'
      versionSelector: 'latestPreRelease'              

- task: VSTest@2
    displayName: 'VSTest - testAssemblies'
    inputs:
       platform: 'x86'
       configuration: '$(BuildConfiguration)'
       testSelector: 'testAssemblies' 
testAssemblyVer2: | # Required when testSelector == TestAssemblies
         ***unittests.dll
        ***unittests.build.appxrecipe
         !***TestAdapter.dll
         !**obj** 
       searchFolder: '$(Build.SourcesDirectory)/src'
       resultsFolder: '$(System.DefaultWorkingDirectory)TestResults'
       runInParallel: false
       codeCoverageEnabled: true
       rerunFailedTests: false
       runTestsInIsolation: true
       runOnlyImpactedTests: false
        
- task: PublishTestResults@2
   displayName: 'Publish Test Results **/TEST-*.xml'
  condition: always()

This is another one of those posts so I can remember where some useful information is….

If you are migrating your Azure DevOps Classic Builds and Release to Multi-Stage YAML then an import step is to export all the exiting build, task groups and release as YAML files.

You can do this by hand within the Pipeline UI, with a lot of cut and pasting, but much easier is to use the excellent Yamlizr – Azure DevOps Classic-to-YAML Pipelines CLI from Alex Vincent. A single CLI command exports everything with a Team project into a neat folder structure of template base YAML.

I cannot recommend the tool enough

I have had a ThinkPad Active Pen (model SD60G957200) ever since I got my Lenovo X1 Carbon Extreme.

The pen, when it works, has worked well. However, the problem has been that whether the pen and PC detected each other seemed very hit and miss.

Today I found the root cause. It was not drivers or dodgy Bluetooth as I had thought, but a weak spring inside the pen. It was not so weak that the battery rattled, but weak enough that the electrical circuit was not being closed reliably on the battery.

The fix was to replace the weak spring with new one out of an old ball point pen. Once this was done the pen became instantly reliable.

Wish I had spotted that sooner.

Updated 11 Nov 2020: I may have spoken too soon, it is back to it’s old behaviour today 🙁

However, I think it could just be the AAAA battery. Seems it is not a good idea to leave a battery in when the pen is not is use given the pen has no power switch.

The Black Live Matter movement has engendered many conversations, hopefully starting changes for the good. Often these changes involve the use of language. One such change has been the move to stop using the name master and switching to the name main for the trunk/default branch in Git repos. This change is moving apace driven by tools such as GitHub and Azure DevOps .

I have recently had need, for the first time since swapping my default branch name in new repos to main, to use Semantic Version and the GitVersion tool.

‘Out of the box’ I hit a problem. The current shipping version of GitVersion (5.3.2) by default makes the assumption that’s the trunk branch is called master. Hence, throws an exception if this branch cannot be found.

Looking at the project’s repo you can find PRs, tagged for a future release, that address this constraint. However, you don’t have to wait for a new version to ship to use this excellent tool in repos with other branch naming conventions.

The solution is to create an override file GitVersion.yml in the root of your repo with the following content to alter the Regex used to find branches. Note that the content below is as a minimum, you can override any other default configuration values in this file as needed.

branches:
   master:
      regex: ^master$|^main$

With this override file the default branch can be either master or main.

You can of course use a different name or limit the Regex to a single name as you need.

Azure DevOps YAML base pipelines allow the pipeline definitions to be treated like any other code. So you make changes in a branch and PR them into the main/trunk when they are approved.

This works well if all the YAML files are in the same repo, but not so well if you are using YAML templates and the templated YAML is stored in a different repo. This is because an Azure DevOps PR is limited to a single repo. So testing a change to a YAML template in a different repo needs a bit of thought.

Say for example you have a template called core.yml in a repo called YAMLTemplates and you make a change to it and start a PR. Unless you have a test YAML pipeline in that repo, which is not a stupid idea, but not always possible depending on the complexity of your build process, there is no way to test the change inside that repo.

The answer is to create a temporary branch in a repo that consumes the shared YAML template. In this temporary branch make an edit to the repository setting that references the shared YAML repo to point to the update branch contain the PR

resources: 
repositories:
  - repository: YAMLTemplates
   type: git
   name: 'Git Project/YAMLTemplates'
# defaults to ref: 'refs/heads/master'
ref: 'refs/heads/newbranch'

You don’t need to make any change to the line where the template is used

extends:  
template: core.yml@YAMLTemplates
  parameters:
    customer: ${{parameters.Customer}}
    useSonarQube: ${{parameters.useSonarQube}}

You can then use this updated pipeline to validated your PR. Once you are happy it works you can

1. Complete the PR in the YAML Templates repo
2. Delete the temporary branch in your consuming repo.