Implement workflow instance deleter with support for locking

src/core/Elsa.Abstractions/Services/Workflows/IWorkflowInstanceDeleter.cs

@@ -0,0 +1,19 @@
+using System.Threading;
+using System.Threading.Tasks;
+using Elsa.Models;
+
+namespace Elsa.Services
+{
+    public interface IWorkflowInstanceDeleter
+    {
+        Task<DeleteWorkflowInstanceResult> DeleteAsync(string workflowInstanceId, CancellationToken cancellationToken = default);
+    }
+
+    public record DeleteWorkflowInstanceResult(DeleteWorkflowInstanceResultStatus Status, WorkflowInstance? WorkflowInstance);
+
+    public enum DeleteWorkflowInstanceResultStatus
+    {
+        Ok,
+        NotFound
+    }
+}

src/core/Elsa.Core/Decorators/LockingWorkflowInstanceDeleter.cs

@@ -0,0 +1,33 @@
+using System.Threading;
+using System.Threading.Tasks;
+using Elsa.Exceptions;
+using Elsa.Options;
+using Elsa.Services;
+
+namespace Elsa.Decorators
+{
+    public class LockingWorkflowInstanceDeleter : IWorkflowInstanceDeleter
+    {
+        private readonly IWorkflowInstanceDeleter _workflowInstanceDeleter;
+        private readonly IDistributedLockProvider _distributedLockProvider;
+        private readonly ElsaOptions _elsaOptions;
+
+        public LockingWorkflowInstanceDeleter(IWorkflowInstanceDeleter workflowInstanceDeleter, IDistributedLockProvider distributedLockProvider, ElsaOptions elsaOptions)
+        {
+            _workflowInstanceDeleter = workflowInstanceDeleter;
+            _distributedLockProvider = distributedLockProvider;
+            _elsaOptions = elsaOptions;
+        }
+
+        public async Task<DeleteWorkflowInstanceResult> DeleteAsync(string workflowInstanceId, CancellationToken cancellationToken = default)
+        {
+            var workflowInstanceLockKey = $"workflow-instance:{workflowInstanceId}";
+            await using var workflowInstanceLockHandle = await _distributedLockProvider.AcquireLockAsync(workflowInstanceLockKey, _elsaOptions.DistributedLockTimeout, cancellationToken);
+
+            if (workflowInstanceLockHandle == null)
+                throw new LockAcquisitionException("Could not acquire a lock within the configured amount of time");
+
+            return await _workflowInstanceDeleter.DeleteAsync(workflowInstanceId, cancellationToken);
+        }
+    }
+}

src/core/Elsa.Core/Extensions/ElsaServiceCollectionExtensions.cs

@@ -56,7 +56,7 @@ namespace Microsoft.Extensions.DependencyInjection
         {
             TypeDescriptor.AddAttributes(typeof(Type), new TypeConverterAttribute(typeof(TypeTypeConverter)));
         }
-        
+
         public static IServiceCollection AddElsaCore(
             this IServiceCollection services,
             Action<ElsaOptionsBuilder>? configure = default)
@@ -91,11 +91,13 @@ namespace Microsoft.Extensions.DependencyInjection
                 .AddConfiguration()
                 .AddCoreActivities();
 
-            services.Decorate<IWorkflowDefinitionStore, InitializingWorkflowDefinitionStore>();
-            services.Decorate<IWorkflowDefinitionStore, EventPublishingWorkflowDefinitionStore>();
-            services.Decorate<IWorkflowInstanceStore, EventPublishingWorkflowInstanceStore>();
-            services.Decorate<IWorkflowInstanceExecutor, LockingWorkflowInstanceExecutor>();
-            services.Decorate<IWorkflowInstanceCanceller, LockingWorkflowInstanceCanceller>();
+            services
+                .Decorate<IWorkflowDefinitionStore, InitializingWorkflowDefinitionStore>()
+                .Decorate<IWorkflowDefinitionStore, EventPublishingWorkflowDefinitionStore>()
+                .Decorate<IWorkflowInstanceStore, EventPublishingWorkflowInstanceStore>()
+                .Decorate<IWorkflowInstanceExecutor, LockingWorkflowInstanceExecutor>()
+                .Decorate<IWorkflowInstanceCanceller, LockingWorkflowInstanceCanceller>()
+                .Decorate<IWorkflowInstanceDeleter, LockingWorkflowInstanceDeleter>();
 
             //TenantId default source
             services.TryAddScoped<ITenantAccessor, DefaultTenantAccessor>();
@@ -128,7 +130,7 @@ namespace Microsoft.Extensions.DependencyInjection
             elsaOptions.Services.AddTransient<IHandleMessages<TMessage>, TConsumer>();
             return elsaOptions;
         }
-        
+
         public static ElsaOptionsBuilder AddPubSubConsumer<TConsumer, TMessage>(this ElsaOptionsBuilder elsaOptions, string? queueName = default) where TConsumer : class, IHandleMessages<TMessage>
         {
             elsaOptions.Services.AddTransient<IHandleMessages<TMessage>, TConsumer>();
@@ -139,7 +141,7 @@ namespace Microsoft.Extensions.DependencyInjection
         public static IServiceCollection AddActivityPropertyOptionsProvider<T>(this IServiceCollection services) where T : class, IActivityPropertyOptionsProvider => services.AddSingleton<IActivityPropertyOptionsProvider, T>();
         public static IServiceCollection AddRuntimeSelectItemsProvider<T>(this IServiceCollection services) where T : class, IRuntimeSelectListItemsProvider => services.AddScoped<IRuntimeSelectListItemsProvider, T>();
         public static IServiceCollection AddActivityTypeProvider<T>(this IServiceCollection services) where T : class, IActivityTypeProvider => services.AddSingleton<IActivityTypeProvider, T>();
-        
+
         public static IServiceCollection AddWorkflowStorageProvider<T>(this IServiceCollection services) where T : class, IWorkflowStorageProvider =>
             services
                 .AddSingleton<T>()
@@ -176,6 +178,7 @@ namespace Microsoft.Extensions.DependencyInjection
                 .AddScoped<IWorkflowTriggerInterruptor, WorkflowTriggerInterruptor>()
                 .AddScoped<IWorkflowReviver, WorkflowReviver>()
                 .AddScoped<IWorkflowInstanceCanceller, WorkflowInstanceCanceller>()
+                .AddScoped<IWorkflowInstanceDeleter, WorkflowInstanceDeleter>()
                 .AddSingleton<IWorkflowFactory, WorkflowFactory>()
                 .AddTransient<IWorkflowBlueprintMaterializer, WorkflowBlueprintMaterializer>()
                 .AddSingleton<IWorkflowBlueprintReflector, WorkflowBlueprintReflector>()
@@ -189,7 +192,7 @@ namespace Microsoft.Extensions.DependencyInjection
                 .AddTransient<ICreatesActivityExecutionContextForActivityBlueprint, ActivityExecutionContextForActivityBlueprintFactory>()
                 .AddTransient<IGetsStartActivities, GetsStartActivitiesProvider>()
                 ;
-            
+
             // Data Protection.
             services.AddDataProtection();
 
@@ -215,14 +218,14 @@ namespace Microsoft.Extensions.DependencyInjection
                 .AddWorkflowProvider<DatabaseWorkflowProvider>();
 
             services.Configure<BlobStorageWorkflowProviderOptions>(o => o.BlobStorageFactory = StorageFactory.Blobs.InMemory);
-            
+
             // Workflow Storage Providers.
             services
                 .AddSingleton<IWorkflowStorageService, WorkflowStorageService>()
                 .AddWorkflowStorageProvider<TransientWorkflowStorageProvider>()
                 .AddWorkflowStorageProvider<WorkflowInstanceWorkflowStorageProvider>()
                 .AddWorkflowStorageProvider<BlobStorageWorkflowStorageProvider>();
-            
+
             services.Configure<BlobStorageWorkflowStorageProviderOptions>(o => o.BlobStorageFactory = StorageFactory.Blobs.InMemory);
 
             // Metadata.

src/core/Elsa.Core/Services/Workflows/WorkflowInstanceDeleter.cs

@@ -0,0 +1,28 @@
+using System.Threading;
+using System.Threading.Tasks;
+using Elsa.Persistence;
+
+namespace Elsa.Services.Workflows
+{
+    public class WorkflowInstanceDeleter : IWorkflowInstanceDeleter
+    {
+        private readonly IWorkflowInstanceStore _workflowInstanceStore;
+
+        public WorkflowInstanceDeleter(IWorkflowInstanceStore workflowInstanceStore)
+        {
+            _workflowInstanceStore = workflowInstanceStore;
+        }
+
+        public async Task<DeleteWorkflowInstanceResult> DeleteAsync(string workflowInstanceId, CancellationToken cancellationToken = default)
+        {
+            var workflowInstance = await _workflowInstanceStore.FindByIdAsync(workflowInstanceId, cancellationToken);
+
+            if (workflowInstance == null)
+                return new DeleteWorkflowInstanceResult(DeleteWorkflowInstanceResultStatus.NotFound, null);
+
+            await _workflowInstanceStore.DeleteAsync(workflowInstance, cancellationToken);
+
+            return new DeleteWorkflowInstanceResult(DeleteWorkflowInstanceResultStatus.Ok, workflowInstance);
+        }
+    }
+}

src/server/Elsa.Server.Api/Endpoints/WorkflowInstances/Delete.cs

@@ -1,6 +1,7 @@
 using System.Threading;
 using System.Threading.Tasks;
 using Elsa.Persistence;
+using Elsa.Services;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Mvc;
 using Swashbuckle.AspNetCore.Annotations;
@@ -13,11 +14,11 @@ namespace Elsa.Server.Api.Endpoints.WorkflowInstances
     [Produces("application/json")]
     public class Delete : Controller
     {
-        private readonly IWorkflowInstanceStore _workflowInstanceStore;
+        private readonly IWorkflowInstanceDeleter _workflowInstanceDeleter;
 
-        public Delete(IWorkflowInstanceStore workflowInstanceStore)
+        public Delete(IWorkflowInstanceDeleter workflowInstanceDeleter)
         {
-            _workflowInstanceStore = workflowInstanceStore;
+            _workflowInstanceDeleter = workflowInstanceDeleter;
         }
 
         [HttpDelete]
@@ -31,12 +32,11 @@ namespace Elsa.Server.Api.Endpoints.WorkflowInstances
         ]
         public async Task<IActionResult> Handle(string id, CancellationToken cancellationToken = default)
         {
-            var workflowInstance = await _workflowInstanceStore.FindByIdAsync(id, cancellationToken);
+            var result = await _workflowInstanceDeleter.DeleteAsync(id, cancellationToken);
 
-            if (workflowInstance == null)
+            if (result.Status == DeleteWorkflowInstanceResultStatus.NotFound)
                 return NotFound();
-            
-            await _workflowInstanceStore.DeleteAsync(workflowInstance, cancellationToken);
+
             return NoContent();
         }
     }