Fix broken Instant activity

src/activities/Elsa.Activities.Timers/Activities/InstantEvent/InstantEvent.cs

@@ -16,10 +16,28 @@ namespace Elsa.Activities.Timers
     )]
     public class InstantEvent : Activity
     {
+        private readonly IClock _clock;
+
+        public InstantEvent(IClock clock)
+        {
+            _clock = clock;
+        }
+        
         [ActivityProperty(Hint = "An instant in the future at which this activity should execute.")]
         public Instant Instant { get; set; }
+        
+        public Instant ExecuteAt
+        {
+            get => GetState<Instant>();
+            set => SetState(value);
+        }
+
+        protected override IActivityExecutionResult OnExecute(ActivityExecutionContext context)
+        {
+            ExecuteAt = Instant;
+            return Suspend();
+        }
 
-        protected override IActivityExecutionResult OnExecute(ActivityExecutionContext context) => context.WorkflowExecutionContext.IsFirstPass ? (IActivityExecutionResult)Done() : Suspend();
         protected override IActivityExecutionResult OnResume() => Done();
     }
 }

src/activities/Elsa.Activities.Timers/HostedServices/TimersHostedService.cs

@@ -48,7 +48,7 @@ namespace Elsa.Activities.Timers.HostedServices
                         var now = _clock.GetCurrentInstant();
                         await workflowScheduler.TriggerWorkflowsAsync<TimerEventTrigger>(x => x.ExecuteAt <= now, cancellationToken: stoppingToken);
                         await workflowScheduler.TriggerWorkflowsAsync<CronEventTrigger>(x => x.ExecuteAt <= now, cancellationToken: stoppingToken);
-                        await workflowScheduler.TriggerWorkflowsAsync<InstantEventTrigger>(x => x.Instant <= now, cancellationToken: stoppingToken);
+                        await workflowScheduler.TriggerWorkflowsAsync<InstantEventTrigger>(x => x.ExecuteAt <= now, cancellationToken: stoppingToken);
                     }
                     catch (Exception ex)
                     {

src/activities/Elsa.Activities.Timers/Services/IInstantEventManager.cs

@@ -1,10 +0,0 @@
-using System.Threading;
-using System.Threading.Tasks;
-
-namespace Elsa.Activities.Timers.Services
-{
-    public interface IInstantEventManager
-    {
-        Task TriggerInstantEventsAsync(CancellationToken cancellationToken);
-    }
-}

src/activities/Elsa.Activities.Timers/Services/InstantEventManager.cs

@@ -1,42 +0,0 @@
-using System.Threading;
-using System.Threading.Tasks;
-using Elsa.Activities.Timers.Triggers;
-using Elsa.Indexes;
-using Elsa.Services;
-using Elsa.Triggers;
-using NodaTime;
-using Open.Linq.AsyncExtensions;
-
-namespace Elsa.Activities.Timers.Services
-{
-    public class InstantEventManager : IInstantEventManager
-    {
-        private readonly IWorkflowSelector _workflowSelector;
-        private readonly IWorkflowInstanceManager _workflowInstanceManager;
-        private readonly IClock _clock;
-
-        public InstantEventManager(IWorkflowSelector workflowSelector, IWorkflowInstanceManager workflowInstanceManager, IClock clock)
-        {
-            _workflowSelector = workflowSelector;
-            _workflowInstanceManager = workflowInstanceManager;
-            _clock = clock;
-        }
-
-        public async Task TriggerInstantEventsAsync(CancellationToken cancellationToken)
-        {
-            var now = _clock.GetCurrentInstant();
-            var candidates = await _workflowSelector.SelectWorkflowsAsync<InstantEventTrigger>(x => x.Instant <= now, cancellationToken).ToList();
-
-            foreach (var candidate in candidates)
-            {
-                // Only trigger workflows that haven't already executed.
-                var instanceCount = await _workflowInstanceManager.Query<WorkflowInstanceIndex>(x => x.WorkflowDefinitionId == candidate.WorkflowBlueprint.Id).CountAsync();
-                
-                if(instanceCount > 0)
-                    continue;
-                
-                
-            }
-        }
-    }
-}

src/activities/Elsa.Activities.Timers/Triggers/InstantEventTrigger.cs

@@ -13,7 +13,7 @@ namespace Elsa.Activities.Timers.Triggers
         /// <summary>
         /// The instant at which the event should trigger.
         /// </summary>
-        public Instant Instant { get; set; }
+        public Instant ExecuteAt { get; set; }
 
         public override bool IsOneOff => true;
     }
@@ -34,16 +34,16 @@ namespace Elsa.Activities.Timers.Triggers
             // Only provide a trigger if the workflow hasn't executed already sometime in the past.
             var workflowDefinitionId = context.ActivityExecutionContext.WorkflowExecutionContext.WorkflowBlueprint.Id;
             var instanceCount = await _workflowInstanceManager.ListByDefinitionAsync(workflowDefinitionId, cancellationToken).Count();
-            var configuredInstant = await context.Activity.GetPropertyValueAsync(x => x.Instant, cancellationToken);
+            var executeAt = context.Activity.GetState(x => x.ExecuteAt);
             var now = _clock.GetCurrentInstant();
 
             // If the configured instant lies in the past, and the workflow was already executed once, we don't trigger again.
-            if (configuredInstant <= now && instanceCount > 0)
+            if (executeAt <= now && instanceCount > 0)
                 return NullTrigger.Instance;
             
             return new InstantEventTrigger
             {
-                Instant = await context.Activity.GetPropertyValueAsync(x => x.Instant, cancellationToken)
+                ExecuteAt = executeAt
             };
         }
     }

src/core/Elsa.Abstractions/Triggers/TriggerProviderContext.cs

@@ -11,7 +11,7 @@ namespace Elsa.Triggers
         }
 
         public ActivityExecutionContext ActivityExecutionContext { get; }
-        public ActivityBlueprintWrapper<TActivity> GetActivity<TActivity>() where TActivity : IActivity => new ActivityBlueprintWrapper<TActivity>(ActivityExecutionContext);
+        public ActivityBlueprintWrapper<TActivity> GetActivity<TActivity>() where TActivity : IActivity => new(ActivityExecutionContext);
     }
 
     public class TriggerProviderContext<T> : TriggerProviderContext where T:IActivity