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Curiosus.DateTime.DbSync

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IDateTimeService that returns the current UTC time of the database server instead of the local clock. Use it when several app instances must agree on "now" (expirations, schedules) even if their clocks drift.

Installation​

dotnet add package Curiosus.DateTime.DbSync

Usage​

DbDateTime:
  SyncPeriodMin: 30
// requires ICuriosusDataContextFactory (Curiosus.DAL) to be registered
services.AddDbSyncDateTimeServices(configuration.DbDateTime);

public class InvoiceService
{
    private readonly IDateTimeService _dateTimeService;

    public InvoiceService(IDateTimeService dateTimeService)
    {
        _dateTimeService = dateTimeService;
    }

    public bool IsOverdue(Invoice invoice) => invoice.DueDateUtc < _dateTimeService.GetCurrentTimeUtc();
}

DbSyncDateTimeService reads the server time with ICuriosusDataContext.GetImmediateServerTimeUtcAsync and keeps the offset from the local clock, so GetCurrentTimeUtc() doesn't query the database. The offset is measured by an IAppInitializer on startup (run by the Curiosus.Hosting bootstrappers or host.InitAsync()) and refreshed by a hosted service every SyncPeriodMin minutes.

Inherit from DbSyncDateTimeService and call AddDbSyncDateTimeServices<TService>(options) to customize it. Register it before any other IDateTimeService (e.g. AddLocalDateTimeService()): registrations use TryAdd.

See also​