public RecurringHostedService(ILogger <RecurringHostedService <TService> > logger,
IServiceScopeFactory serviceScopeFactory,
RecurringServiceOptionsCollection optionsCollection)
{
_logger = logger;
_serviceScopeFactory = serviceScopeFactory;
_optionsCollection = optionsCollection;
}
/// <summary>
/// Registers a recurring task which will be triggered according to the TimeSpan parameter. A service class may not be registered multiple times.
/// </summary>
/// <typeparam name="TService"></typeparam>
/// <param name="services"></param>
/// <param name="timeSpan"></param>
/// <returns></returns>
/// <exception cref="ArgumentException">When <paramref name="timeSpan"/> is less than one second.</exception>
public static IServiceCollection AddRecurringTask <TService>(this IServiceCollection services, TimeSpan timeSpan) where TService : class, IRecurringService
{
// validate the timespan
if (timeSpan.TotalSeconds < 1)
{
throw new ArgumentException("TimeSpan must be greater than 1 second.", nameof(timeSpan));
}
// if the options collection is not yet registered, then register as a singleton
ServiceDescriptor collectionServiceDescriptor = services
.Where(e => e.Lifetime == ServiceLifetime.Singleton)
.Where(e => e.ServiceType == typeof(RecurringServiceOptionsCollection))
.FirstOrDefault();
RecurringServiceOptionsCollection optionsCollection = null;
if (collectionServiceDescriptor == null)
{
optionsCollection = new RecurringServiceOptionsCollection();
services.AddSingleton(typeof(RecurringServiceOptionsCollection), optionsCollection);
}
else
{
optionsCollection = collectionServiceDescriptor.ImplementationInstance as RecurringServiceOptionsCollection;
}
// validate the type doesn't already exist
if (optionsCollection.TypeOptions.ContainsKey(typeof(TService)))
{
throw new InvalidOperationException($"The type {typeof(TService)} has already been registered as a recurring task. A type may only be registered one time.");
}
optionsCollection.TypeOptions.Add(typeof(TService), new RecurringServiceOptions()
{
TimeSpan = timeSpan
});
// register the primary hosted service
services.AddHostedService <RecurringHostedService <TService> >();
// register the service itself as transient so the hosted service can instantiate each run
services.AddTransient <TService>();
return(services);
}