private async Task <string> ClockNameForEvent(
IScheduledCommand <TAggregate> scheduledCommandEvent,
CommandSchedulerDbContext db)
{
// TODO: (ClockNameForEvent) clean this up
var clockName =
scheduledCommandEvent.IfTypeIs <IHaveExtensibleMetada>()
.Then(e => ((object)e.Metadata)
.IfTypeIs <IDictionary <string, object> >()
.Then(m => m.IfContains("ClockName")
.Then(v => v.ToString())))
.ElseDefault();
if (clockName == null)
{
clockName = GetClockName(scheduledCommandEvent);
if (clockName == null)
{
var lookupValue = GetClockLookupKey(scheduledCommandEvent);
clockName = (await db.ClockMappings
.Include(m => m.Clock)
.SingleOrDefaultAsync(c => c.Value == lookupValue))
.IfNotNull()
.Then(c => c.Clock.Name)
.Else(() => SqlCommandScheduler.DefaultClockName);
}
}
return(clockName);
}
private static async Task <ScheduledCommand> GetStoredScheduledCommand <TAggregate>(
IScheduledCommand <TAggregate> scheduledCommand,
CommandSchedulerDbContext db,
Guid scheduledCommandGuid) where TAggregate : class
{
var sequenceNumber = scheduledCommand
.IfTypeIs <IEvent>()
.Then(c => c.SequenceNumber)
.Else(() => scheduledCommand
.IfTypeIs <ScheduledCommand <TAggregate> >()
.Then(c => c.SequenceNumber))
.ElseThrow(() => new InvalidOperationException("Cannot look up stored scheduled command based on a " + scheduledCommand.GetType()));
var storedCommand = await db.ScheduledCommands
.SingleOrDefaultAsync(
c => c.AggregateId == scheduledCommandGuid &&
c.SequenceNumber == sequenceNumber);
return(storedCommand);
}
internal static async Task <ScheduledCommand> StoreScheduledCommand <TAggregate>(
IScheduledCommand <TAggregate> scheduledCommand,
Func <CommandSchedulerDbContext> createDbContext,
Func <IScheduledCommand <TAggregate>, CommandSchedulerDbContext, Task <string> > clockNameForEvent)
where TAggregate : class
{
ScheduledCommand storedScheduledCommand;
using (var db = createDbContext())
{
var domainTime = Domain.Clock.Now();
// get or create a clock to schedule the command on
var clock = scheduledCommand.Clock as Clock;
if (clock == null)
{
var clockName = await clockNameForEvent(scheduledCommand, db);
var clockStartTime = scheduledCommand.Clock?.Now() ??
domainTime;
clock = await GetOrAddSchedulerClock(
db,
clockName,
clockStartTime);
}
storedScheduledCommand = CreateStoredScheduledCommand(
scheduledCommand,
domainTime,
clock);
if (scheduledCommand.IsDue() &&
!scheduledCommand.Command.RequiresDurableScheduling())
{
storedScheduledCommand.NonDurable = true;
return(storedScheduledCommand);
}
Debug.WriteLine(
$"Storing command '{scheduledCommand.Command.CommandName}' ({scheduledCommand.TargetId}:{storedScheduledCommand.SequenceNumber}) on clock '{clock.Name}'");
await SaveScheduledCommandToDatabase(db,
storedScheduledCommand,
scheduledCommand);
}
scheduledCommand.IfTypeIs <ScheduledCommand <TAggregate> >()
.ThenDo(c => c.SequenceNumber = storedScheduledCommand.SequenceNumber);
return(storedScheduledCommand);
}
private static ScheduledCommand CreateStoredScheduledCommand <TAggregate>(
IScheduledCommand <TAggregate> scheduledCommand,
DateTimeOffset domainTime,
Clock schedulerClock)
where TAggregate : class =>
new ScheduledCommand
{
AggregateId = ScheduledCommand <TAggregate> .TargetGuid(scheduledCommand),
SequenceNumber = scheduledCommand
.IfTypeIs <IEvent>()
.Then(e => e.SequenceNumber)
.Else(() => - DateTimeOffset.UtcNow.Ticks),
AggregateType = Command.TargetNameFor(scheduledCommand.Command.GetType()),
SerializedCommand = scheduledCommand.ToJson(),
CreatedTime = domainTime,
DueTime = scheduledCommand.DueTime ?? schedulerClock.Now(),
Clock = schedulerClock
};
private async Task Deliver(IScheduledCommand <TAggregate> scheduledCommand, bool durable)
{
IClock clock = null;
if (scheduledCommand.DueTime != null)
{
clock = Domain.Clock.Create(() => scheduledCommand.DueTime.Value);
}
using (CommandContext.Establish(scheduledCommand.Command, clock))
{
Debug.WriteLine("SqlCommandScheduler.Deliver: " + Description(scheduledCommand));
var repository = getRepository();
var result = await repository.ApplyScheduledCommand(scheduledCommand,
() => commandPreconditionVerifier.VerifyPrecondition(scheduledCommand));
Activity.OnNext(result);
scheduledCommand.IfTypeIs <CommandScheduled <TAggregate> >()
.ThenDo(c => c.Result = result);
if (!durable)
{
return;
}
using (var db = createCommandSchedulerDbContext())
{
var storedCommand = await db.ScheduledCommands
.SingleAsync(c => c.AggregateId == scheduledCommand.AggregateId &&
c.SequenceNumber == scheduledCommand.SequenceNumber);
storedCommand.Attempts++;
if (result.WasSuccessful)
{
storedCommand.AppliedTime = Domain.Clock.Now();
}
else
{
var failure = (CommandFailed)result;
// reschedule as appropriate
var now = Domain.Clock.Now();
if (failure.RetryAfter != null)
{
Debug.WriteLine("SqlCommandScheduler.Deliver (scheduling retry): " + Description(scheduledCommand));
storedCommand.DueTime = now + failure.RetryAfter;
}
else
{
Debug.WriteLine("SqlCommandScheduler.Deliver (abandoning): " + Description(scheduledCommand));
// no further retries
storedCommand.FinalAttemptTime = now;
}
db.Errors.Add(new CommandExecutionError
{
ScheduledCommand = storedCommand,
Error = result.IfTypeIs <CommandFailed>()
.Then(f => f.Exception.ToJson()).ElseDefault()
});
}
await db.SaveChangesAsync();
}
}
}