Grumson.Utilities.TaskQueue 1.0.4

Grumson.Utilities.TaskQueue

The TaskQueue class provides a mechanism to enqueue and process tasks with priorities. It ensures that tasks are executed based on their priority, where lower values indicate higher priority.

Features

• Rule-based preemption of tasks with lower priority by tasks with higher priority.
• Enqueue tasks with a specified priority.
• Check if a specific task is completed.
• Wait until all tasks are completed.

TaskQueue

Properties

Constructors

• TaskQueue(List<PreemptionRule> preemptionRules): Initializes a new instance of the TaskQueue class with the specified preemption rules.

Public Methods

• Guid EnqueueTask(Func<CancellationToken, Task> task, int priority): Enqueues a new task with the specified priority.
• Task<bool> IsTaskCompletedAsync(Guid taskId): Checks if a task with a given ID is completed.
• Task AllTasksCompletedAsync(): Waits until all tasks are completed.
• CancelAllTasks: Cancels all tasks in the queue.

Private Methods

• Task ProcessQueueAsync(): Processes the task queue. This method is called internally to process tasks based on their priority. If preemption rules are defined, it preempts tasks as needed.
• Task<bool> PreemptTaskAsync(Guid taskId): Preempts a task with the specified ID. This method is called internally to preempt tasks based on preemption rules.

Usage

Initialization

To initialize a TaskQueue, provide a list of preemption rules:

var preemptionRules = new List { 
	new PreemptionRule(0, 4),	// Priority 0 tasks can preempt priority 4 tasks 
	new PreemptionRule(1, 5),	// Priority 1 tasks can preempt priority 5 tasks 
								// Add more rules as needed 
};

var taskQueue = new TaskQueue(preemptionRules);

Enqueueing Tasks

To enqueue a new task with a specified priority:

// Enqueue methods as tasks with priorities
var taskId1 = taskQueue.EnqueueTask(Method1, 4); // Lower priority
var taskId2 = taskQueue.EnqueueTask(Method2, 0); // Higher priority

Checking Task Completion

To check if a specific task is completed:

bool isCompleted = await taskQueue.IsTaskCompletedAsync(taskId);

Waiting for All Tasks to Complete

To wait until all tasks in the queue are completed:

await taskQueue.AllTasksCompletedAsync();

Cancelling All Tasks

To cancel all tasks in the queue:

taskQueue.CancelAllTasks();

Example

Here is a complete example of how to use the TaskQueue class:

using System;
using System.Threading.Tasks;

public class Program
{
    public static async Task Main(string[] args)
    {
        // Define preemption rules
        var preemptionRules = new List<PreemptionRule>
        {
            new PreemptionRule(0, 4), // Priority 0 can preempt priority 4
            new PreemptionRule(0, 5), // Priority 0 can preempt priority 5
            // Add more rules as needed
        };

        var taskQueue = new TaskQueue(preemptionRules);

        // Enqueue methods as tasks with priorities
        var taskId1 = taskQueue.EnqueueTask(Method1, 4); // Lower priority
        var taskId2 = taskQueue.EnqueueTask(Method2, 0); // Higher priority

        // Wait for all tasks to complete
        await taskQueue.AllTasksCompletedAsync();
        Console.WriteLine("All tasks completed");

        // Check if individual tasks are completed
        Console.WriteLine($"Task1 completed: {await taskQueue.IsTaskCompletedAsync(taskId1)}");
        Console.WriteLine($"Task2 completed: {await taskQueue.IsTaskCompletedAsync(taskId2)}");
    }

    public static async Task Method1(CancellationToken token)
    {
        // Your async task 1
        for (int i = 0; i < 10; i++)
        {
            token.ThrowIfCancellationRequested();
            await Task.Delay(100);
            Console.WriteLine("Method1 running");
        }
        Console.WriteLine("Method1 completed");
    }

    public static async Task Method2(CancellationToken token)
    {
        // Your async task 2
        for (int i = 0; i < 5; i++)
        {
            token.ThrowIfCancellationRequested();
            await Task.Delay(100);
            Console.WriteLine("Method2 running");
        }
        Console.WriteLine("Method2 completed");
    }
}

Changelog

This section outlines the changes and improvements made in each version of the TaskQueue.

Version 1.0.4 - 2023-09-10

Fixed

• Add SemaphoreSlim to prevent race conditions in the TaskQueue.

Version 1.0.3 - 2023-09-05

• TaskQueue.cs. Changed task completion methods to use TrySetResult, TrySetCanceled, and TrySetException`.

Version 1.0.2 - 2023-09-04

New

• CanlAllTasks method to cancel all tasks in the queue.

Version 1.0.1 - 2023-09-04

Enhanced

• QueuedTask with priority, and CancellationToken.

Expanded

• Preemption features and examples.

Improved

• TaskQueue with preemption logic and priority handling.

Introduced

• PreemptionRule class for defining preemption rules.

Version 1.0.0 - 2023-09-04

• Initial release of the TaskQueue.