A while ago, we at Pentia took over a massive Sitecore solution, which after 16 years of upgrades and development the maintenance cost consumed the entire digital budget of the customer.
In other words, the client was at a crossroad – to build new or renovate.
For this client the answer was relatively easy:
- Firstly, the number of features and functionalities in the platform is vast, and just to scope and specify the entire platform was a massive, if not impossible, undertaking – and one which would claim a large number of resources internally and externally.
- Secondly, while building a new platform (a massive task), the existing platform would have to be kept alive and slowly (painfully slowly) phased out over time. This means double resources for development, maintenance and operations.
- Thirdly – and probably the most deterring factor – the change management involved in retraining the thousands of staff involved in and around the platform and across departments was substantial and disruptive to the entire organization.
Therefore, a renovation project was established, and the first task was to reduce technical debt for the solution.
Reducing maintenance cost
One of the best ways to reduce technical debt is to reduce the code base, less code == less maintenance cost. In this case we managed to delete 33% of the code base, here are a few key figures for the solution when we took it over.
- 900+ sites (over ½ million items)
- 15 years old (multiple upgrades from Sitecore 4.x to 8.2 and single migration)
- 15 integrations
- 600+ Layouts/sub layouts
- Many JavaScript applications (Angular/React/Backbone/knockout/native/JQuery)
- Code
- 294030 lines code
- Cyclomatic Complexity – main project 9662 average 1200
- Depth of Inheritance – main project 17 average 8
- Class Coupling – main project 1400, average 500
- Single solution multiple roles
- Content management
- Content delivery
- Publishing
- Utility/API
- Bot
- No Access to production (apart from Sitecore client)
- Manual deploys to Production
- 2 separate solutions (Intranet & Websites) merged into a single solution 4 years ago
- Not Helix compliant (sort of n-tier where projects had numbers)
The Challenge
Due to the sheer size of the solution, no one in the client’s organization knew which features were used and how much and no access to. There were many clear indications of code not being used or referred.
So, the initial task was to identify and remove unnecessary parts of the solution.
But how to you identify redundant code?
Visual studio has tools for that, unfortunately Sitecore/web application introduce additional challenges as un-referenced C# code can still be executed due to the following:
- Configuration – pipelines, event handlers, custom configuration, etc.
- Sitecore content – items that define that specific functions on a class should be executed i.e. WFFM.
- Sitecore rendering engine that renders the presentation using web controls, layouts, sub layouts, controllers, code, etc.
In addition, then we must identify if the code used by the following is ever called
- Layouts
- Sub Layouts
- Controllers
- Web Controls
- XSLT’s
- Rest APi’s
- Soap Web Services
Solution
As in most renovation projects, there is no silver bullet, it requires a longsighted plan, structured methodology, concepts, code, tools and continuous effort to reduce technical debt.
Ironically to reduce the code base you must introduce more code.
Custom Attributes
We introduced several custom attributes to help mark up the code and help identify issues to be address.
- Obsolete
- Used
- Refactor
- Ignore Empty Try Catch (see part 2)
Used
The point of this attribute is to clearly mark that a loosely referenced class, method or interface is indeed needed by the solution.
In other words, it indicates that a class, method or interface is used, even though it has no references. It’s possible to add a text to explain how and where it is used.
Obsolete
Whilst .net provides the Obsolete custom attribute; there are some missing options to indicate that the code is obsolete, and can be removed when a condition is met:
- Specific date
- Specific release is in production
- 3rd party system is updated to a specific version
The point of this attribute was therefore to allow us to plan the renovation project in stages and remove code when the referring parts were cleaned up.
Refactor
During this project we ran into many pieces of code, classes and structures which were in dire need of refactoring. But because of constraints in time, code not deployed, lack of knowledge, dependencies, multiple version of 3rd party system, or for some other reason it was not possible at that time.
Therefore, the best we could do was add this attribute and define why it should be refactored, and why it hasn’t been refactored.
The purpose of this attribute was therefore documentation and planning of the renovation process
Introducing a “Ensure Code Is Obsolete” Service
It is very difficult to ensure that code is obsolete and is never called and that is why it is so difficult to delete code.
What we needed was a somewhat conclusive measurement if the running code was being executed.
What we decided to do was to introduce code in the solution that collected data on code executed across all running solution instances and aggregated the data and presented the results, to ensure that the code was not required.
The IIncrementCountService interface was introduced to provide the ability to count how often the code is executed and then send the results to be aggregated with the other instances, by the content management server.
public interface IIncrementCountService
{
bool IncrementCount(Type type,string name);
}
Implementation Challenges
The Content Management, Content Delivery, Utility & API instances are in different network zones without access to each other.
The implementation must have a minimum impact on performance, network traffic, database storage.
Not introduce any new databases and or tables.
As we do not have access to production environment apart from the Sitecore Client, it is not possible log the data the file system.
Sitecore Remote Events
Remote events (see this blog for a good introduction) provide the perfect mechanism to allow all instances to send their counter data to the Content Management service which is responsible for aggregating the data and presenting the results.
You must be careful with events as if you flood the event queue table it can kill the performance of ALL your sitecore instances.
The following configuration was introduced (see my blog post on Type Safe Settings) so the IncrementCount function will only raises an event when one of the following is true:
- The count exceeds 1000
- The threshold of 15 minutes is reached
- A new day starts
This ensures that the event queue is not overloaded and will minimize performance impact, network & database usage.
<configuration xmlns:patch="http://www.sitecore.net/xmlconfig/" xmlns:environment="http://www.sitecore.net/xmlconfig/environment" xmlns:role="http://www.sitecore.net/xmlconfig/role/">
<sitecore>
<feature>
<Diagnostics>
<CounterSettings type="Feature.Diagnostics.Infrastructure.CounterSettings, Feature.Diagnostics" singleInstance="true">
<ThresholdCount>1000</ThresholdCount>
<ThresholdTime>15</ThresholdTime>
<Enabled>true</Enabled>
</CounterSettings>
</Diagnostics>
</feature>
</sitecore>
</configuration>
The IncrementLocalCountService class is responsible for incrementing the count, caching it locally and raising the event to notify the Content Management server, when one of the afore mention threshold is met.
public class IncrementLocalCountService : IIncrementCountService
{
private readonly IList<Counter> _counters = new List<Counter>();
private readonly CounterFactory _counterFactory;
private readonly CounterUpdateRemoteEventFactory _counterUpdateRemoteEventFactory;
private readonly CounterSettings _counterSettings;
public IncrementLocalCountService([NotNull]CounterFactory counterFactory,
[NotNull]CounterUpdateRemoteEventFactory counterUpdateRemoteEventFactory,
[NotNull]CounterSettings counterSettings)
{
Assert.ArgumentNotNull(counterFactory, nameof(counterFactory));
Assert.ArgumentNotNull(counterUpdateRemoteEventFactory, nameof(counterUpdateRemoteEventFactory));
Assert.ArgumentNotNull(counterSettings, nameof(counterSettings));
_counterFactory = counterFactory;
_counterUpdateRemoteEventFactory = counterUpdateRemoteEventFactory;
_counterSettings = counterSettings;
}
public bool IncrementCount(Type type,string name)
{
if (string.IsNullOrWhiteSpace(name))
return false;
if (_counterSettings == null || !_counterSettings.Enabled)
return false;
DateTime today = DateTime.Now.Date;
// any from yesterday Flush
Counter counter = _counters.FirstOrDefault(c => c.Name == name && c.Date == today && c.Type == type);
if (counter == null)
{
counter = _counterFactory.Create(name, today, 0);
_counters.Add(counter);
}
counter.Count++;
Flush(today);
return true;
}
private void Flush(DateTime today)
{
//iterate over all counters, flush that exceed the threshold count or time restriction
foreach (var counter in GetThresholdExceeded())
{
RaiseEvent(counter);
_counters.Remove(counter);
}
}
private IEnumerable<Counter> GetThresholdExceeded()
{
DateTime timeLimit = DateTime.Now.Subtract(new TimeSpan(0, _counterSettings.ThresholdTime, 0));
return _counters.Where(c => c.Created < timeLimit || c.Count >= _counterSettings.ThresholdCount).ToList();
}
private void RaiseEvent(Counter counter)
{
if (counter == null)
return;
var counterUpdateRemoteEvent = _counterUpdateRemoteEventFactory.Create(counter.Name, counter.Date, counter.Count);
Sitecore.Eventing.EventManager.QueueEvent(counterUpdateRemoteEvent,true,true);
}
}
Who is responsible for aggregating the results?
The content Management is responsible for aggregating the results. It requires some extra configuration, to register that it will subscribe to handle remote events, raise the event and it then handle the remote event (see blog for more information).
<configuration xmlns:patch="http://www.sitecore.net/xmlconfig/" xmlns:set="http://www.sitecore.net/xmlconfig/set/" xmlns:role="http://www.sitecore.net/xmlconfig/role/">
<sitecore role:require="Standalone OR ContentManagement">
<events>
<event name="counter:update:remote">
<handler type="Feature.Diagnostics.Infrastructure.Events.Counter.CounterUpdateRemoteEventHandler, Feature.Diagnostics" method="Update" />
</event>
</events>
<pipelines>
<initialize>
<processor type="Feature.Diagnostics.Infrastructure.Pipelines.Counter.SubscribeToCounterRemoteEventService, Feature.Diagnostics" />
</initialize>
</pipelines>
</sitecore>
</configuration>
The code associated with the configuration above.
public class CounterUpdateRemoteEventHandler
{
public void Update(object sender, EventArgs args)
{
if (args == null)
return;
try
{
var countRemoteEventArgs = args as RemoteEventArgs<CounterUpdateRemoteEvent>;
Assert.IsNotNull(countRemoteEventArgs, $"Unexpected event args: {args.GetType().FullName}");
Assert.IsNotNull(countRemoteEventArgs.Event, $"Event is nul: {args.GetType().FullName}");
var counterRepository = ServiceLocator.ServiceProvider.GetService<CounterRepository>();
Assert.IsNotNull(counterRepository, $"Could not resolve type:{typeof(CounterRepository).FullName}");
var counterFactory = ServiceLocator.ServiceProvider.GetService<CounterFactory>();
Assert.IsNotNull(counterFactory, $"Could not resolve type:{typeof(CounterFactory).FullName}");
var @event = countRemoteEventArgs.Event;
var counter = counterFactory.Create(@event.Name, @event.Date, @event.Count);
if (counter == null)
return;
counterRepository.Update(counter);
}
catch (Exception exception)
{
Log.Error($"CounterUpdateRemoteEventHandler.Update - failed", exception);
}
}
}
public class SubscribeToCounterRemoteEventService
{
public void Process(PipelineArgs args)
{
Sitecore.Diagnostics.Log.Info("SubscribeToCounterRemoteEventService.Initialize Called",this);
var action = new Action<CounterUpdateRemoteEvent>(RaiseRemoteEvent);
EventManager.Subscribe(action);
}
public void RaiseRemoteEvent(CounterUpdateRemoteEvent counterUpdateRemoteEvent)
{
if (counterUpdateRemoteEvent == null)
return;
RemoteEventArgs<CounterUpdateRemoteEvent> remoteEventArgs = new RemoteEventArgs<CounterUpdateRemoteEvent>(counterUpdateRemoteEvent);
Event.RaiseEvent(counterUpdateRemoteEvent.EventName, remoteEventArgs);
}
}
Where is the Data Saved?
Ideally it should be saved in its own SQL database.
Unfortunately, we were not allowed to introduce and new databases and or tables, so we had to use the sitecore IDTable. The CounterRepository is responsible for retrieving, updating and persisting the counters in the IDTable.
public class CounterRepository
{
private readonly CounterFactory _counterFactory;
private readonly GenerateKeyService _generateKeyService;
public CounterRepository([NotNull] CounterFactory counterFactory,
[NotNull]GenerateKeyService generateKeyService)
{
Assert.ArgumentNotNull(counterFactory, nameof(counterFactory));
Assert.ArgumentNotNull(generateKeyService, nameof(generateKeyService));
_counterFactory = counterFactory;
_generateKeyService = generateKeyService;
}
public bool Update([NotNull] Counter counter)
{
Assert.ArgumentNotNull(counter, nameof(counter));
var counterInDatabase = Get(counter.Name, counter.Date);
if (counterInDatabase == null)
return Add(counter);
counter.Count += counterInDatabase.Count;
Delete(counterInDatabase);
return Add(counter);
}
public IEnumerable<Counter> Get()
{
var idTableEntries = IDTable.GetKeys(Constants.IdTable.Prefix);
return idTableEntries == null ? new List<Counter>() : _counterFactory.Create(idTableEntries);
}
private bool Add(Counter counter)
{
if (counter == null)
return false;
var idTableEntry = IDTable.Add(Constants.IdTable.Prefix,
_generateKeyService.GenerateKey(counter.Name, counter.Date),new ID(Guid.NewGuid()),
ID.Null,counter.Count.ToString());
return idTableEntry != null;
}
private void Delete(Counter counter)
{
if (counter == null)
return;
IDTable.RemoveKey(Constants.IdTable.Prefix, _generateKeyService.GenerateKey(counter.Name, counter.Date));
}
private Counter Get(string name, DateTime date)
{
if (string.IsNullOrWhiteSpace(name))
return null;
var idTableEntry = IDTable.GetID(Constants.IdTable.Prefix, _generateKeyService.GenerateKey(name, date));
if (idTableEntry == null)
return null;
if (!long.TryParse(idTableEntry.CustomData, out var count))
count = 0;
return _counterFactory.Create(name, date, count);
}
}
Presenting the results
No magic here a simple counter.aspx pages, which reads from the CounterRepository and displays it in a table, with the option to clear the database. Also some code to ensure that only Sitecore administrators can access the page. See Part 2 in the series.
Alan Coates - Sitecore/.NET blog 