TaskGuidance.BackgroundProcessing 1.0.1

TaskGuidance.BackgroundProcessing

Task Processing Engine which controls asynchronous, priority-based, output-optional actions/tasks for .NET

Features

• Enqueue multiple executable actions concurrently
• Actions support priority levels (Higher priority tasks will be started first)
• Actions support timeouts
• Supports Non-Blocking Actions (Actions which do not return an output)
• Supports Blocking Actions (Caller thread waits for the desired output from the action processed in the background)
• Filtration; Explicitly control a set of actions which can proceed for execution
• Global Cancellation (Stops and cancels all ongoing background actions/tasks)
• Optional Internal logging
  • Control Log Level and integrate extensible Log sink

Documentation

IResponsibilities exposes IResponsibilities.ConfigureNew, which internally initializes the TaskProcessingEngine. You may supply additional optional parameters during setup for filtration.

IResponsibilities.ConfigureNew cancels all attached in-progress background actions, stops the actions which have not yet started, re-configures possible invocable actions (optional parameter), and restarts both TaskProcessingEngine and itself.

TOutput IResponsibilities.QueueBlockingAction<TOutput> enqueues blocking actions, schedules them for background execution, and finally waits for the output. ManualResetEventSlim is internally used to release the calling thread, waiting for the output.

void IResponsibilities.QueueAction enqueues non-blocking actions and schedules them for background execution.

The IResponsibilities implicitly uses and controls an TaskProcessingEngine which has

• A Concurrent Priority Queue for deciding which actions/tasks to be dequeued and started first
• An always-running global Task-Processing logic; which dequeues actions/tasks and executes them asynchronously (i.e in the background).

Any actions/tasks to be enqueued must inherit from the abstract class BaseAction<TInput, TOutput> which has

• Its own cancellation capabilities (ICancellationManager)
• A TInput Input and an optional TOutput output
• A TimeSpan TimeOut, for throwing timeout exceptions if the BaseAction execution exceeds the specified value
• An ActionPriorityValues enum which holds the priority for scheduling and execution
• A string UniqueName, which helps filtering actions from enqueueing

BaseAction internally contains a well-defined workflow which not only wraps the overridden custom logic, but also extends exception handling capabilities. When an BaseAction is started from the TaskProcessingEngine, the following occurs in order:

1. TOutput BaseAction<TInput, TOutput>.DefaultOutput - Initialization of default output
2. Task<bool> BaseAction<TInput, TOutput>.ShouldProceed - Check to determine whether the core logic should proceed
3. Task<TOutput> BaseAction<TInput, TOutput>.Action - Core Logic
4. Task BaseAction<TInput, TOutput>.PostAction - Post-processing logic
5. Task BaseAction<TInput, TOutput>.OnActionEnd - Additional logic after returning result

Custom handling of errors/exceptions during processing is also available.

• Task BaseAction<TInput, TOutput>.OnTimeOut - If Core logic times out
• Task BaseAction<TInput, TOutput>.OnCancellation - If Cancellation is Requested
• Task BaseAction<TInput, TOutput>.OnFailure - If an error or a failure occurs

DI Registration

You can either register manually the following dependencies:

RegisterTransient<ICancellationManager, CancellationManager>();
RegisterSingleton<IResponsibilities, Responsibilities>();
RegisterSingleton<ITaskProcessingEngine, TaskProcessingEngine>();
RegisterSingleton<ITaskProcessorConfiguration, TaskProcessorConfiguration>();

Or you can wrap your chosen DI Container under IDependencyContainer and call GuidanceDependencyRegistration.Register(IDependencyContainer) to implicitly register all dependencies during startup.

//Example
public class DependencyContainer : TaskGuidance.BackgroundProcessing.Dependencies.IDependencyContainer
{
    IServiceCollection ServiceDescriptors { get; }

    void IDependencyContainer.RegisterSingleton<T1, T2>()
    {
        ServiceDescriptors.AddSingleton<T1, T2>();
    }

    .
    .

Configuration Settings

Configure ITaskProcessorConfiguration during startup:

ITaskProcessorConfiguration.ProcessorQueueSize

• Integer - Denotes the Action Queue Initial Capacity. Default is 100 if not specified.

ITaskProcessorConfiguration.ProcessorWaitTimeWhenQueueEmpty_InMilliseconds

• Integer - Control the Aggression of checking new Actions to process if Queue is found empty. Default is 1000ms / 1s if not specified

Example Usage

// Define an action 
public class SomeAction : BaseAction<InputData, OutputData>
{
    /* Override logic and define properties */
}

// From DI..
IResponsibilities Responsibilities; 

// Configure 
Responsibilities.ConfigureNew(invocableActionNames: null);

// Create an instance of the action 
var someAction = new SomeAction(new InputData 
{
     
});

// Support Cancellation and binding capabilities 
someAction.SupportCancellation();

// Retrieve output (for blocking actions)
OutputData output = Responsibilities.QueueBlockingAction<OutputData>(someAction, executeSeparately: false);

Contributing

Contributions are always welcome!

Authors

• @endecipher

License

MIT