How to Safely Cancel an Async Operation in C#

Asynchronous programming is essential for building responsive applications, but it comes with challenges - particularly when you need to cancel operations.

Here's how to safely implement cancellation in C#.

Using CancellationTokenSource

The key to proper cancellation is the CancellationTokenSource class. This provides a token that can be passed to async methods and monitored for cancellation requests.

// Create a cancellation source with timeout
var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
var token = cts.Token;

try
{
    // Pass token to async operations
    await DoLongRunningTaskAsync(token);
}
catch (OperationCanceledException)
{
    // Handle cancellation gracefully
    Console.WriteLine("Operation was canceled");
}
finally
{
    // Always dispose the CancellationTokenSource
    cts.Dispose();
}

Implementing Cancellation in Your Methods

When writing cancellable async methods, check for cancellation at appropriate points:

async Task DoLongRunningTaskAsync(CancellationToken token)
{
    // Check before starting expensive work
    token.ThrowIfCancellationRequested();
    
    for (int i = 0; i < 100; i++)
    {
        // Periodically check during loops
        if (token.IsCancellationRequested)
        {
            // Clean up resources if needed
            CleanupResources();
            
            // Then throw the standard exception
            throw new OperationCanceledException(token);
        }
        
        await Task.Delay(100, token); // Built-in methods accept tokens
    }
}

Best Practices

  1. Always dispose of CancellationTokenSource objects
  2. Use token.ThrowIfCancellationRequested() for cleaner code
  3. Check for cancellation before expensive operations
  4. Pass the token to all nested async calls
  5. Handle OperationCanceledException appropriately in your calling code

By following these patterns, you can ensure your async operations respond promptly to cancellation requests while maintaining clean, resource-efficient code.

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Related

In C#, you can format an integer with commas (thousands separator) using ToString with a format specifier.

int number = 1234567;
string formattedNumber = number.ToString("N0"); // "1,234,567"
Console.WriteLine(formattedNumber);

Explanation:

"N0": The "N" format specifier stands for Number, and "0" means no decimal places. The output depends on the culture settings, so in regions where , is the decimal separator, you might get 1.234.567.

Alternative:

You can also specify culture explicitly if you need a specific format:

using System.Globalization;

int number = 1234567;
string formattedNumber = number.ToString("N0", CultureInfo.InvariantCulture);
Console.WriteLine(formattedNumber); // "1,234,567"
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391

Slow initial load times can drive users away from your React application. One powerful technique to improve performance is lazy loading - loading components only when they're needed.

Let's explore how to implement this in React.

The Problem with Eager Loading

By default, React bundles all your components together, forcing users to download everything upfront. This makes navigation much quicker and more streamlined once this initial download is complete.

However, depending on the size of your application, it could also create a long initial load time.

import HeavyComponent from './HeavyComponent';
import AnotherHeavyComponent from './AnotherHeavyComponent';

function App() {
  return (
    <div>
      {/* These components load even if user never sees them */}
      <HeavyComponent />
      <AnotherHeavyComponent />
    </div>
  );
}

React.lazy() to the Rescue

React.lazy() lets you defer loading components until they're actually needed:

import React, { lazy, Suspense } from 'react';

// Components are now loaded only when rendered
const HeavyComponent = lazy(() => import('./HeavyComponent'));
const AnotherHeavyComponent = lazy(() => import('./AnotherHeavyComponent'));

function App() {
  return (
    <div>
      <Suspense fallback={<div>Loading...</div>}>
        <HeavyComponent />
        <AnotherHeavyComponent />
      </Suspense>
    </div>
  );
}

Route-Based Lazy Loading

Combine with React Router for even better performance:

import React, { lazy, Suspense } from 'react';
import { BrowserRouter, Routes, Route } from 'react-router-dom';

const Home = lazy(() => import('./pages/Home'));
const Dashboard = lazy(() => import('./pages/Dashboard'));
const Settings = lazy(() => import('./pages/Settings'));

function App() {
  return (
    <BrowserRouter>
      <Suspense fallback={<div>Loading...</div>}>
        <Routes>
          <Route path="/" element={<Home />} />
          <Route path="/dashboard" element={<Dashboard />} />
          <Route path="/settings" element={<Settings />} />
        </Routes>
      </Suspense>
    </BrowserRouter>
  );
}

Implement these techniques in your React application today and watch your load times improve dramatically!

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When working with URLs in C#, encoding is essential to ensure that special characters (like spaces, ?, &, and =) don’t break the URL structure. The recommended way to encode a string for a URL is by using Uri.EscapeDataString(), which converts unsafe characters into their percent-encoded equivalents.

string rawText = "hello world!";
string encodedText = Uri.EscapeDataString(rawText);

Console.WriteLine(encodedText); // Output: hello%20world%21

This method encodes spaces as %20, making it ideal for query parameters.

For ASP.NET applications, you can also use HttpUtility.UrlEncode() (from System.Web), which encodes spaces as +:

using System.Web;

string encodedText = HttpUtility.UrlEncode("hello world!");
Console.WriteLine(encodedText); // Output: hello+world%21

For .NET Core and later, Uri.EscapeDataString() is the preferred choice.

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