Implement optimistic locking scale-tone#8

* No more bulk operations for CUD, using async tasks instead
* Removing entities also respects version field
* Update caching behavior to handle partial failure in optimistic locking scenario

Sources/Linq2DynamoDb.DataContext.Tests/Entities/Book.cs

@@ -32,6 +32,9 @@ public class Book : EntityBase
 		[DynamoDBProperty(typeof(StringTimeSpanDictionaryConverter))]
 		public IDictionary<string, TimeSpan> FilmsBasedOnBook { get; set; }
 
+        [DynamoDBVersion]
+        public int? VersionNumber { get; set; }
+
 		public enum Popularity
 		{
 			Low,

Sources/Linq2DynamoDb.DataContext.Tests/Entities/BookPoco.cs

@@ -30,6 +30,9 @@ public class BookPoco {
         [DynamoDBProperty(typeof(StringTimeSpanDictionaryConverter))]
         public IDictionary<string, TimeSpan> FilmsBasedOnBook { get; set; }
 
+        [DynamoDBVersion]
+        public int? VersionNumber { get; set; }
+
         public enum Popularity {
             Low,
 

Sources/Linq2DynamoDb.DataContext.Tests/EntityManagementTests/EntityCreationTests.cs

@@ -33,17 +33,18 @@ public void DataContext_EntityCreation_PersistsRecordToDynamoDb()
             Assert.IsNotNull(storedBook);
         }
 
-        [Ignore("This behavior is currently expected. SubmitChanges() uses DocumentBatchWrite, which only supports PUT operations, which by default replaces existing entities")]
         [Test]
-        [ExpectedException(typeof(InvalidOperationException), ExpectedMessage = "cannot be added, because entity with that key already exists", MatchType = MessageMatch.Contains)]
+        [ExpectedException(typeof(AggregateException))]
         public void DataContext_EntityCreation_ThrowsExceptionWhenEntityAlreadyExistsInDynamoDbButWasNeverQueriedInCurrentContext()
         {
-            var book = BooksHelper.CreateBook(popularityRating: Book.Popularity.Average);
+            var persistedBook = BooksHelper.CreateBook(popularityRating: Book.Popularity.Average);
 
-            book.PopularityRating = Book.Popularity.High;
+            var bookCopy = BooksHelper.CreateBook(name: persistedBook.Name, publishYear: persistedBook.PublishYear, persistToDynamoDb: false);
+
+            bookCopy.PopularityRating = Book.Popularity.High;
 
             var booksTable = this.Context.GetTable<Book>();
-            booksTable.InsertOnSubmit(book);
+            booksTable.InsertOnSubmit(bookCopy);
             this.Context.SubmitChanges();
         }
 

Sources/Linq2DynamoDb.DataContext.Tests/EntityManagementTests/EntityModificationTests.cs

@@ -1,7 +1,9 @@
 using Linq2DynamoDb.DataContext.Tests.Entities;
 using Linq2DynamoDb.DataContext.Tests.Helpers;
 using NUnit.Framework;
+using System;
 using System.Collections.Generic;
+using System.Linq;
 
 namespace Linq2DynamoDb.DataContext.Tests.EntityManagementTests
 {
@@ -50,28 +52,7 @@ public void DataContext_EntityModification_UpdateRecordWithNewArray()
 
             CollectionAssert.AreEquivalent(storedBook.RentingHistory, storedBookAfterModification.RentingHistory);
         }
-
-        [Ignore("This behavior is currently expected. SubmitChanges() uses DocumentBatchWrite, which only supports PUT operations with default 'replace' behavior")]
-        [Test]
-        public void DataContext_EntityModification_UpdateShouldNotAffectFieldsModifiedFromOutside()
-        {
-            var book = BooksHelper.CreateBook(popularityRating: Book.Popularity.Average, persistToDynamoDb: false);
-
-            var booksTable = this.Context.GetTable<Book>();
-            booksTable.InsertOnSubmit(book);
-            this.Context.SubmitChanges();
-
-            // Update record from outside of DataTable
-            BooksHelper.CreateBook(book.Name, book.PublishYear, numPages: 15);
-
-            book.PopularityRating = Book.Popularity.High;
-            this.Context.SubmitChanges();
-
-            var storedBook = booksTable.Find(book.Name, book.PublishYear);
-            Assert.AreEqual(book.PopularityRating, storedBook.PopularityRating, "Record was not updated");
-            Assert.AreEqual(book.NumPages, 15, "Update has erased changes from outside");
-        }
-
+
         [Test]
         public void DataContext_UpdateEntity_UpdatesRecordWhenOldRecordIsNull()
         {

Sources/Linq2DynamoDb.DataContext.Tests/EntityManagementTests/Poco/PocoCreationTests.cs

@@ -33,20 +33,6 @@ public void DataContext_EntityCreation_PersistsRecordToDynamoDb()
             Assert.IsNotNull(storedBookPoco);
         }
 
-        [Ignore("This behavior is currently expected. SubmitChanges() uses DocumentBatchWrite, which only supports PUT operations, which by default replaces existing entities")]
-        [Test]
-        [ExpectedException(typeof(InvalidOperationException), ExpectedMessage = "cannot be added, because entity with that key already exists", MatchType = MessageMatch.Contains)]
-        public void DataContext_EntityCreation_ThrowsExceptionWhenEntityAlreadyExistsInDynamoDbButWasNeverQueriedInCurrentContext()
-        {
-            var book = BookPocosHelper.CreateBookPoco(popularityRating: BookPoco.Popularity.Average);
-
-            book.PopularityRating = BookPoco.Popularity.High;
-
-            var booksTable = this.Context.GetTable<BookPoco>();
-            booksTable.InsertOnSubmit(book);
-            this.Context.SubmitChanges();
-        }
-
         [Test]
         [ExpectedException(typeof(InvalidOperationException), ExpectedMessage = "cannot be added, because entity with that key already exists", MatchType = MessageMatch.Contains)]
         public void DataContext_EntityCreation_ThrowsExceptionWhenTryingToAddSameEntityTwice()

Sources/Linq2DynamoDb.DataContext.Tests/EntityManagementTests/Poco/PocoModificationTests.cs

@@ -51,27 +51,6 @@ public void DataContext_EntityModification_UpdateRecordWithNewArray()
             CollectionAssert.AreEquivalent(storedBookPoco.RentingHistory, storedBookPocoAfterModification.RentingHistory);
         }
 
-        [Ignore("This behavior is currently expected. SubmitChanges() uses DocumentBatchWrite, which only supports PUT operations with default 'replace' behavior")]
-        [Test]
-        public void DataContext_EntityModification_UpdateShouldNotAffectFieldsModifiedFromOutside()
-        {
-            var book = BookPocosHelper.CreateBookPoco(popularityRating: BookPoco.Popularity.Average, persistToDynamoDb: false);
-
-            var booksTable = this.Context.GetTable<BookPoco>();
-            booksTable.InsertOnSubmit(book);
-            this.Context.SubmitChanges();
-
-            // Update record from outside of DataTable
-            BookPocosHelper.CreateBookPoco(book.Name, book.PublishYear, numPages: 15);
-
-            book.PopularityRating = BookPoco.Popularity.High;
-            this.Context.SubmitChanges();
-
-            var storedBookPoco = booksTable.Find(book.Name, book.PublishYear);
-            Assert.AreEqual(book.PopularityRating, storedBookPoco.PopularityRating, "Record was not updated");
-            Assert.AreEqual(book.NumPages, 15, "Update has erased changes from outside");
-        }
-
         [Test]
         public void DataContext_UpdateEntity_UpdatesRecordWhenOldRecordIsNull()
         {

Sources/Linq2DynamoDb.DataContext.Tests/EntityManagementTests/Versioning/EntityVersioningTests.cs

@@ -0,0 +1,91 @@
+using Linq2DynamoDb.DataContext.Tests.Entities;
+using Linq2DynamoDb.DataContext.Tests.Helpers;
+using NUnit.Framework;
+using System;
+using System.Collections.Generic;
+
+namespace Linq2DynamoDb.DataContext.Tests.EntityManagementTests.Versioning 
+{
+    [TestFixture]
+    class EntityVersioningTests : DataContextTestBase
+    {
+        public override void SetUp() 
+        {
+        }
+
+        public override void TearDown() 
+        {
+        }
+
+        [Test]
+        [ExpectedException(typeof(AggregateException))]
+        public void DataContext_UpdateEntity_Does_OptimisticLocking() 
+        {
+            var contextA = TestConfiguration.GetDataContext();
+            var contextB = TestConfiguration.GetDataContext();
+
+            var originalBook = BooksHelper.CreateBook(popularityRating: Book.Popularity.Low, rentingHistory: null);
+            var booksTableA = contextA.GetTable<Book>();
+            var booksTableB = contextB.GetTable<Book>();
+
+            // Read the same entry from the database into two contexts
+            var retrievedBookA = booksTableA.Find(originalBook.Name, originalBook.PublishYear);
+            var retrievedBookB = booksTableB.Find(originalBook.Name, originalBook.PublishYear);
+
+            // Mutate a property on instance A and persist
+            retrievedBookA.PopularityRating = Book.Popularity.Average;
+            contextA.SubmitChanges();
+
+            // Mutate a property on instance B (unaware of changes to A)
+            retrievedBookB.RentingHistory = new List<string> { "history element" };
+            contextB.SubmitChanges();
+        }
+
+        [Test]
+        [ExpectedException(typeof(AggregateException))]
+        public void DataContext_AddEntity_DoesNotOverwrite_ExistingVersionedEntity() 
+        {
+            var contextA = TestConfiguration.GetDataContext();
+            var contextB = TestConfiguration.GetDataContext();
+
+            var tableA = contextA.GetTable<Book>();
+            var tableB = contextB.GetTable<Book>();
+
+            var bookA = BooksHelper.CreateBook(name: "A Tale of Two Books", publishYear: 0, persistToDynamoDb: false);
+            var bookB = BooksHelper.CreateBook(name: "A Tale of Two Books", publishYear: 0, persistToDynamoDb: false);
+
+
+            tableA.InsertOnSubmit(bookA);
+            contextA.SubmitChanges();
+
+            tableB.InsertOnSubmit(bookB);
+            contextB.SubmitChanges();
+        }
+
+        [Test]
+        [ExpectedException(typeof(AggregateException))]
+        public void DataContext_RemoveEntity_RespectsVersionConstraint() 
+        {
+            var book = BooksHelper.CreateBook(numPages: 5, persistToDynamoDb: false);
+
+            var contextA = TestConfiguration.GetDataContext();
+            var contextB = TestConfiguration.GetDataContext();
+
+            var tableA = contextA.GetTable<Book>();
+            var tableB = contextB.GetTable<Book>();
+
+            // Insert the book in Context A
+            tableA.InsertOnSubmit(book);
+            contextA.SubmitChanges();
+
+            // Find and modify the book in Context B
+            var retrievedBook = tableB.Find(book.Name, book.PublishYear);
+            retrievedBook.NumPages = 10;
+            contextB.SubmitChanges();
+
+            // Try to delete the book from Context A
+            tableA.RemoveOnSubmit(book);
+            contextA.SubmitChanges();
+        }
+    }
+}

Sources/Linq2DynamoDb.DataContext.Tests/Helpers/BooksHelper.cs

@@ -28,7 +28,7 @@ public static void CleanSession()
 		{
             Logger.DebugFormat("Removing {0} records from DynamoDb", _recordsForCleanup.Count);
 
-			Parallel.ForEach(_recordsForCleanup, book => PersistenceContext.Delete(book));
+			Parallel.ForEach(_recordsForCleanup, book => PersistenceContext.Delete(book, new DynamoDBOperationConfig { SkipVersionCheck = true, ConsistentRead = true }));
 
 			_recordsForCleanup = new ConcurrentQueue<Book>();
 		}

Sources/Linq2DynamoDb.DataContext.Tests/Linq2DynamoDb.DataContext.Tests.csproj

@@ -90,6 +90,7 @@
     <Compile Include="EntityManagementTests\Poco\PocoCreationTests.cs" />
     <Compile Include="EntityManagementTests\Poco\PocoModificationTests.cs" />
     <Compile Include="EntityManagementTests\Poco\PocoRemovalTests.cs" />
+    <Compile Include="EntityManagementTests\Versioning\EntityVersioningTests.cs" />
     <Compile Include="Helpers\BookPocoHelper.cs" />
     <Compile Include="Helpers\BooksHelper.cs" />
     <Compile Include="Helpers\MemcachedController.cs" />
@@ -140,7 +141,9 @@
       <SubType>Designer</SubType>
     </None>
   </ItemGroup>
-  <ItemGroup />
+  <ItemGroup>
+    <Service Include="{82A7F48D-3B50-4B1E-B82E-3ADA8210C358}" />
+  </ItemGroup>
   <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
   <!-- To modify your build process, add your task inside one of the targets below and uncomment it. 
        Other similar extension points exist, see Microsoft.Common.targets.

Sources/Linq2DynamoDb.DataContext/EntityProxy.cs

@@ -131,6 +131,8 @@ public Document GetDocumentIfDirty()
 
         public object Entity { get { return this.GetTransparentProxy(); } }
 
+        public Document AsDocument() { return _document; }
+
         public void Commit() {}
     }
 }

Sources/Linq2DynamoDb.DataContext/EntityWrapper.cs

@@ -2,6 +2,8 @@
 using System.Linq;
 using Amazon.DynamoDBv2.DocumentModel;
 using Linq2DynamoDb.DataContext.Utils;
+using System.Reflection;
+using Amazon.DynamoDBv2.DataModel;
 
 namespace Linq2DynamoDb.DataContext
 {
@@ -14,6 +16,31 @@ internal class EntityWrapper : IEntityWrapper
         private readonly IEntityKeyGetter _keyGetter;
         private Document _doc, _newDoc;
 
+        private PropertyInfo _entityVersionNumberProperty;
+        private bool _hasResolvedEntityVersionNumberProperty;
+
+        /// <summary>
+        /// Gets PropertyInfo for the entity's property that has [DynamoDBVersion] 
+        /// attribute or returns null if there is none.
+        /// </summary>
+        private PropertyInfo EntityVersionNumberProperty {
+            get {
+                if (!_hasResolvedEntityVersionNumberProperty) {
+                    _entityVersionNumberProperty = Entity
+                        .GetType()
+                        .GetProperties(BindingFlags.Public | BindingFlags.Instance)
+                        .Where(property =>
+                            property
+                                .GetCustomAttributes(typeof(DynamoDBVersionAttribute), true)
+                                .SingleOrDefault() != null
+                        ).SingleOrDefault();
+
+                    _hasResolvedEntityVersionNumberProperty = true;
+                }
+                return _entityVersionNumberProperty;
+            }
+        }
+
         internal EntityWrapper(object entity, Func<object, Document> conversionFunctor, IEntityKeyGetter keyGetter)
         {
             this.Entity = entity;
@@ -38,14 +65,16 @@ internal EntityWrapper(Document doc, Type entityType, Func<object, Document> con
         /// </summary>
         internal bool IsCommited { get; private set; }
 
+        public Document AsDocument() {  return this._conversionFunctor(this.Entity); }
+
         /// <summary>
         /// Returns a new document, if the entity was modified since the last call to this method.
         /// Otherwise returns null.
         /// </summary>
         /// <returns></returns>
         public Document GetDocumentIfDirty()
         {
-            this._newDoc = this._conversionFunctor(this.Entity);
+            this._newDoc = AsDocument();
 
             if (this._doc == null)
             {
@@ -101,9 +130,28 @@ public void Commit()
         {
             this._doc = this._newDoc;
             this._newDoc = null;
+            this.UpdateEntityVersionNumber();
             this.IsCommited = true;
         }
 
+        /// <summary>
+        /// Sets the value of the Entity's propety that has the DynamoDBVersionAttribute to 
+        /// the value in _doc. When adding/updating the document the version number will
+        /// change in the _doc on the way to DynamoDB 
+        /// </summary>
+        private void UpdateEntityVersionNumber() 
+        {
+            if (EntityVersionNumberProperty == default(PropertyInfo))
+            {
+                return;
+            }
+
+            EntityVersionNumberProperty.SetValue(
+                Entity,
+                this._doc[EntityVersionNumberProperty.Name].ToObject(EntityVersionNumberProperty.PropertyType)
+            );
+        }
+
         #region Redirecting Equals() and GetHashCode() to the underlying entity
 
         public override bool Equals(object obj)

Sources/Linq2DynamoDb.DataContext/IEntityWrapper.cs

@@ -7,5 +7,6 @@ public interface IEntityWrapper
         object Entity { get; }
         Document GetDocumentIfDirty();
         void Commit();
+        Document AsDocument();
     }
 }