private static async Task <Transition> ResolveEventTransitionAsync(this State state, StateMachineContext context, JToken data)
{
Debug.Assert(state != null);
Debug.Assert(context != null);
Debug.Assert(data != null);
var eventSubscriptions = state.Transitions
.Where(t => (t.EventGroups != null && t.EventGroups.Count > 0) &&
string.IsNullOrWhiteSpace(t.Condition) &&
t.Timeout == null)
.Select(t => new EventSubscription {
TargetTransition = t
})
.ToArray();
Func <CancellationToken, Task <Transition> > getTransitionFunc =
async token =>
{
var matches = await EventSubscription.WaitForFirstMatchedSubscriptionAsync(eventSubscriptions, context, data, token);
Debug.Assert(matches != null);
Debug.Assert(matches.Length > 0);
foreach (var match in matches)
{
var json = match.EventInstance.ToJson();
Debug.Assert(json != null);
json.Merge(context.Data, match.Group.ResultHandler, context);
}
return(matches.First().Transition);
};
var timeoutTransition = state.Transitions.SingleOrDefault(t => (!string.IsNullOrWhiteSpace(t.NextState) || t.Action != null) &&
string.IsNullOrWhiteSpace(t.Condition) &&
(t.EventGroups == null || t.EventGroups.Count == 0) &&
t.Timeout != null);
Transition next;
if (timeoutTransition != null)
{
using var localTimeoutCancelTokenSource = new CancellationTokenSource();
using var combined = CancellationTokenSource.CreateLinkedTokenSource(
localTimeoutCancelTokenSource.Token, context.CancelToken);
Task <Transition> timeoutTask = context.Host.DelayAsync(timeoutTransition.Timeout.Value, combined.Token)
.ContinueWith(_ => timeoutTransition);
Debug.Assert(timeoutTask != null);
next = await Task.WhenAny(timeoutTask, getTransitionFunc(combined.Token)).Unwrap();
if (!timeoutTask.IsCompleted)
{
localTimeoutCancelTokenSource.Cancel();
}
}
else
{
next = await getTransitionFunc(context.CancelToken);
}
Debug.Assert(next != null);
return(next);
}