Prolly

⚠️ NOTE: I no longer maintain this project, respond to issues, or address PRs. If anyone else would like to take over as a maintainer, please contact me.

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Really lightweight and simple Circuit Breaker / Timeout library for .NET. Inspired by Hystrix and Polly

Usage

Step 1 : Inherit a command from ProllyCommand

To create a prolly command, create a new class and let it inherit from ProllyCommand<T>. The T should be the return value. Currently void methods aren't supported. This is planned for the future.

When you create a new command you have to specify the command group it belongs to. All commands in a certain command group use the same circuit breaker. You can specify a command group by a key. If it doesn't exist yet, it will be automatically created.

class DemoCommand : ProllyCommand<string>
{
    public DemoCommand()
        :base(CommandGroupKey.Factory.Resolve("Demo"))
    { }

    protected override string Run()
    {
        return CallToExternalSomething();
    }
}

Step 2 : Execute the command

After a new command is created you can execute it by calling the Execute() method.

var command = new DemoCommand();
command.Execute();

Step 3 (optional) : Specifying a fallback

It might be desirable to return a value instead of an exception when an call couldn't be executed properly. For this you can override the Fallback method inside your custom command.

class DemoCommand : ProllyCommand<string>
{
    public DemoCommand()
        : base(CommandGroupKey.Factory.Resolve("Demo"))
    { }

    protected override string Run()
    {
        return CallToExternalSomething();
    }

    protected override string Fallback()
    {
        return "Some fallback data";
    }
}

Configuration

There are a few settings you can tweak. These are currently: the timeout time, the times a call is allowed to fail before the circuit breaker opens and the time the circuit breaker stays open.

Step 1 : Define the configuration Section

Define the configuration section inside your App/Web.config

<configSections>
  <sectionGroup name="prollySettings">
    <section 
      name="prolly" 
      type="Prolly.Configuration.Sections.ProllySection, Prolly" 
      allowLocation="true" 
      allowDefinition="Everywhere" />
  </sectionGroup>
</configSections>

Step 2 : Define your configuration

The configurations will automatically be applied.

<prollySettings>
	<prolly>
	  <timeout miliseconds="1000"/>
	  <circuitBreaker allowedFailures="2" openTimeInMiliseconds="200" />
	  <bulkhead concurrentTasks="2" />
	</prolly>
</prollySettings>

Extra

CircuitBreakerIgnoreException

Sometimes you don't want the circuit breaker to register certain exceptions but want to cascade them upwards. You can do this in Prolly by encapsulating your exception inside an CircuitBreakerIgnoreException. This way the circuit breaker will ignore it.