iasync-enumerable-worker.cs

using APIDocsRider.DB;
using Microsoft.Data.SqlClient;
using Microsoft.EntityFrameworkCore;

namespace APIDocsRider.BL;

public class WorkerService(ILogger<WorkerService> logger, IServiceProvider serviceProvider) : BackgroundService
{
    private readonly IServiceProvider _serviceProvider = serviceProvider;
    private readonly ILogger<WorkerService> _logger = logger;
    
    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        using var scope = _serviceProvider.CreateScope();
        
        try
        {
            // handles service shutdown via deployment or other failures
            while (!stoppingToken.IsCancellationRequested)
            {
                // inject DB context into Hosted Service
                var db = scope.ServiceProvider.GetRequiredService<GamesContext>();

                await foreach (var gameTitle in db.GameModes
                                   .Select(g => g.Title)
                                   .AsAsyncEnumerable() // maps records into stream
                                   .WithCancellation(stoppingToken))
                {
                    _logger.LogInformation("reading: {Game}", gameTitle);

                    // timeout test
                    await Task.Delay(TimeSpan.FromSeconds(10));
                    
                    _logger.LogInformation("passed timeout: {Game}", gameTitle);
                }

                // 30 seconds delay between worker restarts
                await Task.Delay(TimeSpan.FromSeconds(30), stoppingToken);
            }            
        }
        // catches worker failures 
        catch (OperationCanceledException)
        {
            _logger.LogWarning("Worker was cancelled during processing.");
        }
        catch (SqlException ex)
        {
            _logger.LogCritical(ex, "SQL Exception!");

        }
        catch (Exception ex)
        {
            _logger.LogCritical(ex, "Critical Exception!");
        }
    }
}