Bits of .NET

⚡ TAP = Asynchronous Programming

Async is essential. TAP is the standard pattern. Async/await, Task, Task.

📝 TAP Basics

// Basic async method
public async Task GetDataAsync()
{
    using var client = new HttpClient();
    var result = await client.GetStringAsync("https://api.example.com/data");
    return result;
}

// Async with error handling
public async Task GetUserAsync(int id)
{
    try
    {
        var response = await _httpClient.GetAsync($"/api/users/{id}");
        response.EnsureSuccessStatusCode();
        var json = await response.Content.ReadAsStringAsync();
        return JsonSerializer.Deserialize(json);
    }
    catch (Exception ex)
    {
        _logger.LogError(ex, "Error getting user {Id}", id);
        throw;
    }
}

// Async void (avoid, except for events)
public async void Button_Click(object sender, EventArgs e)
{
    await DoWorkAsync();
}

🎯 Advanced TAP

// Multiple async operations (parallel)
public async Task GetUserSummaryAsync(int userId)
{
    var userTask = _userService.GetUserAsync(userId);
    var ordersTask = _orderService.GetUserOrdersAsync(userId);
    var reviewsTask = _reviewService.GetUserReviewsAsync(userId);
    
    await Task.WhenAll(userTask, ordersTask, reviewsTask);
    
    return new UserSummary
    {
        User = userTask.Result,
        Orders = ordersTask.Result,
        Reviews = reviewsTask.Result
    };
}

// Cancellation
public async Task GetUserWithCancellationAsync(
    int id, CancellationToken cancellationToken)
{
    return await _dbContext.Users
        .FindAsync(new object[] { id }, cancellationToken);
}

// Retry pattern
public async Task RetryAsync(
    Func> operation, int maxRetries = 3)
{
    for (int i = 0; i < maxRetries; i++)
    {
        try
        {
            return await operation();
        }
        catch (Exception) when (i < maxRetries - 1)
        {
            await Task.Delay(1000 * (i + 1));
        }
    }
    return await operation();
}

// Timeout
public async Task FetchWithTimeoutAsync(string url, int timeoutMs = 5000)
{
    using var cts = new CancellationTokenSource(timeoutMs);
    try
    {
        using var client = new HttpClient();
        return await client.GetStringAsync(url, cts.Token);
    }
    catch (OperationCanceledException)
    {
        throw new TimeoutException($"Request timed out after {timeoutMs}ms");
    }
}

💡 TAP Tips

• Use async for I/O operations
• Avoid async void (except events)
• Use CancellationToken for timeouts
• Use Task.WhenAll for parallel
• Handle exceptions properly