【C#】ASP.NETで定期実行ならCronosが便利らしい？

cd /usr/src/sample
dotnet new mvc

dotnet add package Cronos

using Cronos;

namespace sample.Services
{
    public class CronJobService : IHostedService, IDisposable
    {
        private System.Timers.Timer? _timer;
        private readonly CronExpression _expression;
        private readonly TimeZoneInfo _timeZoneInfo;

        public CronJobService(IScheduleConfig<CronJobService> config)
        {
            _expression = CronExpression.Parse(config.CronExpression);
            _timeZoneInfo = config.TimeZoneInfo;
        }

        public async Task StartAsync(CancellationToken cancellationToken)
        {
            await ScheduleJob(cancellationToken);
        }

        protected async Task ScheduleJob(CancellationToken cancellationToken)
        {
            var next = _expression.GetNextOccurrence(DateTimeOffset.Now, _timeZoneInfo);
            if (next.HasValue)
            {
                var delay = next.Value - DateTimeOffset.Now;
                if (delay.TotalMilliseconds <= 0)   // prevent non-positive values from being passed into Timer
                {
                    await ScheduleJob(cancellationToken);
                }
                _ = Task.Run(async() => {
                    await Task.Delay((int)delay.TotalMilliseconds, cancellationToken);
                    Console.WriteLine($"Do scheduled task.({DateTimeOffset.Now})");
                    await ScheduleJob(cancellationToken);
                });
            }
            await Task.CompletedTask;
        }

        public async Task StopAsync(CancellationToken cancellationToken)
        {
            _timer?.Stop();
            await Task.CompletedTask;
        }

        public void Dispose()
        {
            _timer?.Dispose();
            GC.SuppressFinalize(this);
        }
    }

    // ReSharper disable once UnusedTypeParameter
    public interface IScheduleConfig<T>
    {
        string CronExpression { get; set; }
        TimeZoneInfo TimeZoneInfo { get; set; }
    }

    public class ScheduleConfig<T> : IScheduleConfig<T>
    {
        public string CronExpression { get; set; } = string.Empty;
        public TimeZoneInfo TimeZoneInfo { get; set; } = TimeZoneInfo.Local;
    }

    public static class ScheduledServiceExtensions
    {
        public static IServiceCollection AddCronJob<T>(this IServiceCollection services, Action<IScheduleConfig<T>> options) where T : CronJobService
        {
            if (options == null)
            {
                throw new ArgumentNullException(nameof(options), @"Please provide Schedule Configurations.");
            }
            var config = new ScheduleConfig<T>();
            options.Invoke(config);
            if (string.IsNullOrWhiteSpace(config.CronExpression))
            {
                throw new ArgumentNullException(nameof(ScheduleConfig<T>.CronExpression), @"Empty Cron Expression is not allowed.");
            }

            services.AddSingleton<IScheduleConfig<T>>(config);
            services.AddHostedService<T>();
            return services;
        }
    }}

using sample.Services;

var builder = WebApplication.CreateBuilder(args);

// Add services to the container.
builder.Services.AddControllersWithViews();

// Add cron service
builder.Services.AddCronJob<CronJobService>(c =>
{
    c.TimeZoneInfo = TimeZoneInfo.Local;
    c.CronExpression = @"*/1 * * * *";
});

var app = builder.Build();
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（以下省略）
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// Add cron service
builder.Services.AddCronJob<CronJobService>(c =>
{
    c.TimeZoneInfo = TimeZoneInfo.Local;
    c.CronExpression = @"*/1 * * * *";
});