public async Task <StateMachineProcessingResults> OnEventAsync(Type stateType, object state, ICorrelationEvent evt)
{
if (_stateMachineTypes == null)
{
throw new Exception("Saga configuration error. You need to configure the SagaStateMachineFactoryBuilder.");
}
var stateMachineType = _stateMachineTypes[stateType];
if (stateMachineType == null)
{
if (_stateMachineTypes.Values.Count == 0)
{
throw new Exception($"State machine type {stateType} not found. No state machines have been scanned. Did you add the assembly via SagaStateMachineFactoryBuilder.WithStateMachinesInAssembiles?");
}
throw new Exception($"State machine type {stateType} not found out of {_stateMachineTypes.Values.Count} state machines.");
}
if (_container == null)
{
throw new Exception("IContainer supplied to SagaStateMachineFactoryBuilder is null.");
}
var stateMachine = _container.GetInstance(stateMachineType);
var methodInfo = stateMachineType.GetMethod("ProcessNextStep", new[] { typeof(Guid), typeof(ICorrelationEvent), stateType, typeof(StateMachineProcessingResults) });
if (methodInfo == null || stateMachine == null)
{
throw new Exception($"No valid state machine {stateMachineType.Name} for state {stateType.Name}.");
}
{
var result = new StateMachineProcessingResults();
await((Task)methodInfo?.Invoke(stateMachine, new[] { evt.CorrelationId, evt, state, result })).ConfigureAwait(false);
return(result);
}
}
public async Task Initialize(T state)
{
var correlationId = Guid.NewGuid();
await _repository.Create(correlationId, state).ConfigureAwait(false);
// create an event to represent the new state of the state machine, having an object instead of null
// avoids having to perform a null check in each state machine
var stateMachineCreatedEvent = new StateMachineCreatedEvent {
CorrelationId = correlationId
};
var firstStepResult = new StateMachineProcessingResults();
await ProcessNextStep(correlationId, stateMachineCreatedEvent, state, firstStepResult).ConfigureAwait(false);
if (firstStepResult.IsSagaComplete)
{
// even though crazy, handle if a saga of a single command has been created
await _repository.Delete(correlationId).ConfigureAwait(false);
}
else
{
await _repository.Update(correlationId, state).ConfigureAwait(false);
}
}
public abstract Task ProcessNextStep(Guid correlationId, ICorrelationEvent evt, T state, StateMachineProcessingResults results);
