InMemory saga persister creates duplicate saga instances

src/NServiceBus.AcceptanceTests/NServiceBus.AcceptanceTests.csproj

@@ -96,6 +96,7 @@
     <Compile Include="PerfMon\CriticalTime\When_deferring_a_message.cs" />
     <Compile Include="PubSub\When_publishing_from_sendonly.cs" />
     <Compile Include="PubSub\When_publishing_an_event_implementing_two_unrelated_interfaces.cs" />
+    <Compile Include="Sagas\When_saga_started_concurrently.cs" />
     <Compile Include="Sagas\When_sagas_cant_be_found.cs" />
     <Compile Include="Sagas\When_using_ReplyToOriginator.cs" />
     <Compile Include="ScaleOut\When_individualization_is_enabled_for_msmq.cs" />

src/NServiceBus.AcceptanceTests/Sagas/When_saga_started_concurrently.cs

@@ -0,0 +1,172 @@
+namespace NServiceBus.AcceptanceTests.Sagas
+{
+    using System;
+    using System.Threading.Tasks;
+    using NServiceBus.AcceptanceTesting;
+    using NServiceBus.AcceptanceTests.EndpointTemplates;
+    using NServiceBus.Config;
+    using NServiceBus.Saga;
+    using NUnit.Framework;
+
+    public class When_saga_started_concurrently : NServiceBusAcceptanceTest
+    {
+        [Test]
+        public void Should_start_single_saga()
+        {
+            var context = new Context
+            {
+                SomeId = Guid.NewGuid().ToString()
+            };
+
+            Scenario.Define(context)
+                .WithEndpoint<ConcurrentHandlerEndpoint>(b =>
+                {
+                    b.When(bus =>
+                    {
+                        Parallel.Invoke(() =>
+                        {
+                            bus.SendLocal(new StartMessageOne
+                            {
+                                SomeId = context.SomeId
+                            });
+                        }, () =>
+                        {
+                            bus.SendLocal(new StartMessageTwo
+                                {
+                                    SomeId = context.SomeId
+                                }
+                            );
+                        });
+                    });
+                })
+                .AllowExceptions()
+                .Done(c => c.PlacedSagaId != Guid.Empty && c.BilledSagaId != Guid.Empty)
+                .Run();
+
+            Assert.AreNotEqual(Guid.Empty, context.PlacedSagaId);
+            Assert.AreNotEqual(Guid.Empty, context.BilledSagaId);
+            Assert.AreEqual(context.PlacedSagaId, context.BilledSagaId, "Both messages should have been handled by the same saga, but SagaIds don't match.");
+        }
+
+        class Context : ScenarioContext
+        {
+            public string SomeId { get; set; }
+            public Guid PlacedSagaId { get; set; }
+            public Guid BilledSagaId { get; set; }
+            public bool SagaCompleted { get; set; }
+        }
+
+        class ConcurrentHandlerEndpoint : EndpointConfigurationBuilder
+        {
+            public ConcurrentHandlerEndpoint()
+            {
+                EndpointSetup<DefaultServer>(b => { })
+                    .WithConfig<TransportConfig>(c =>
+                    {
+                        c.MaxRetries = 3;
+                        c.MaximumConcurrencyLevel = 2;
+                    })
+                    .WithConfig<SecondLevelRetriesConfig>(c =>
+                    {
+                        c.Enabled = false;
+                    });
+            }
+
+            class ConcurrentlyStartedSaga : Saga<ConcurrentlyStartedSagaData>,
+                IAmStartedByMessages<StartMessageTwo>,
+                IAmStartedByMessages<StartMessageOne>
+            {
+                public Context Context { get; set; }
+
+                public void Handle(StartMessageOne message)
+                {
+                    Data.OrderId = message.SomeId;
+                    Data.Placed = true;
+                    Bus.SendLocal(new SuccessfulProcessing
+                    {
+                        SagaId = Data.Id,
+                        Type = nameof(StartMessageOne)
+                    });
+                    CheckForCompletion();
+                }
+
+                public void Handle(StartMessageTwo message)
+                {
+                    Data.OrderId = message.SomeId;
+                    Data.Billed = true;
+                    Bus.SendLocal(new SuccessfulProcessing
+                    {
+                        SagaId = Data.Id,
+                        Type = nameof(StartMessageTwo)
+                    });
+                    CheckForCompletion();
+                }
+
+                protected override void ConfigureHowToFindSaga(SagaPropertyMapper<ConcurrentlyStartedSagaData> mapper)
+                {
+                    mapper.ConfigureMapping<StartMessageOne>(msg => msg.SomeId).ToSaga(saga => saga.OrderId);
+                    mapper.ConfigureMapping<StartMessageTwo>(msg => msg.SomeId).ToSaga(saga => saga.OrderId);
+                }
+
+                void CheckForCompletion()
+                {
+                    if (!Data.Billed || !Data.Placed)
+                    {
+                        return;
+                    }
+                    MarkAsComplete();
+                    Context.SagaCompleted = true;
+                }
+            }
+
+            class ConcurrentlyStartedSagaData : ContainSagaData
+            {
+                [Unique]
+                public virtual string OrderId { get; set; }
+                public virtual bool Placed { get; set; }
+                public virtual bool Billed { get; set; }
+            }
+
+            // Intercepts the messages sent out by the saga
+            class LogSuccessfulHandler : IHandleMessages<SuccessfulProcessing>
+            {
+                public Context Context { get; set; }
+
+                public void Handle(SuccessfulProcessing message)
+                {
+                    if (message.Type == nameof(StartMessageOne))
+                    {
+                        Context.PlacedSagaId = message.SagaId;
+                    }
+                    else if (message.Type == nameof(StartMessageTwo))
+                    {
+                        Context.BilledSagaId = message.SagaId;
+                    }
+                    else
+                    {
+                        throw new Exception("Unknown type");
+                    }
+                }
+            }
+        }
+
+        [Serializable]
+        class StartMessageOne : ICommand
+        {
+            public string SomeId { get; set; }
+        }
+
+        [Serializable]
+        class StartMessageTwo : ICommand
+        {
+            public string SomeId { get; set; }
+        }
+
+        [Serializable]
+        class SuccessfulProcessing : ICommand
+        {
+            public string Type { get; set; }
+            public Guid SagaId { get; set; }
+        }
+    }
+}

src/NServiceBus.Core/NServiceBus.Core.csproj

@@ -266,7 +266,6 @@
     <Compile Include="Unicast\Transport\Config\TransportExtensions.cs" />
     <Compile Include="Unicast\Transport\Config\UseTransportExtensions_Obsolete.cs" />
     <Compile Include="Utils\BaseDictionary.cs" />
-    <Compile Include="Utils\WeakKeyDictionary.cs" />
     <Compile Include="Utils\Guard.cs" />
     <Compile Include="Utils\ExceptionHeaderHelper.cs" />
     <Compile Include="Utils\ElevateChecker.cs" />