[Azure.Core.Amqp] Lazy Allocation for All Sections

The focus of these changes is to enable lazy allocation for all sections
of the `AmqpAnnotatedMessage` type, to match the AMQP spec definition.
(see: http://docs.oasis-open.org/amqp/core/v1.0/os/amqp-core-messaging-v1.0-os.html#section-message-format)

In order to allow downstream consumers to test if a section is populated
without triggering allocation for the property, the `HasSection` member
has been added.

sdk/core/Azure.Core.Amqp/Azure.Core.Amqp.sln

@@ -0,0 +1,31 @@
+
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio Version 16
+VisualStudioVersion = 16.0.31205.134
+MinimumVisualStudioVersion = 10.0.40219.1
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Azure.Core.Amqp", "src\Azure.Core.Amqp.csproj", "{B5AD38C8-DAB6-40E6-AB79-41A8ED9D297B}"
+EndProject
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Azure.Core.Amqp.Tests", "tests\Azure.Core.Amqp.Tests.csproj", "{61ABA08F-FA50-4DEA-8C97-00B7B057BDEF}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|Any CPU = Debug|Any CPU
+		Release|Any CPU = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{B5AD38C8-DAB6-40E6-AB79-41A8ED9D297B}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{B5AD38C8-DAB6-40E6-AB79-41A8ED9D297B}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{B5AD38C8-DAB6-40E6-AB79-41A8ED9D297B}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{B5AD38C8-DAB6-40E6-AB79-41A8ED9D297B}.Release|Any CPU.Build.0 = Release|Any CPU
+		{61ABA08F-FA50-4DEA-8C97-00B7B057BDEF}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{61ABA08F-FA50-4DEA-8C97-00B7B057BDEF}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{61ABA08F-FA50-4DEA-8C97-00B7B057BDEF}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{61ABA08F-FA50-4DEA-8C97-00B7B057BDEF}.Release|Any CPU.Build.0 = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(SolutionProperties) = preSolution
+		HideSolutionNode = FALSE
+	EndGlobalSection
+	GlobalSection(ExtensibilityGlobals) = postSolution
+		SolutionGuid = {1DC074C7-A8F0-4778-B791-323040BDF4C5}
+	EndGlobalSection
+EndGlobal

sdk/core/Azure.Core.Amqp/CHANGELOG.md

@@ -2,14 +2,10 @@
 
 ## 1.2.0-beta.1 (Unreleased)
 
-### Features Added
-
-### Breaking Changes
-
-### Key Bugs Fixed
-
-### Fixed
-
+### Added
+- All section properties of the `AmqpAnnotatedMessage` are now lazily allocated to reflect that they are defined as optional in the AMQP specification, section 3.2.
+
+- The `HasSection` method has been added to `AmqpAnnotatedMessage` to allow inspecting the property for a section to determine if it is populated without triggering an allocation.
 
 ## 1.1.0 (2021-06-16)
 

sdk/core/Azure.Core.Amqp/api/Azure.Core.Amqp.netstandard2.0.cs

@@ -26,6 +26,7 @@ public AmqpAnnotatedMessage(Azure.Core.Amqp.AmqpMessageBody body) { }
         public Azure.Core.Amqp.AmqpMessageHeader Header { get { throw null; } }
         public System.Collections.Generic.IDictionary<string, object> MessageAnnotations { get { throw null; } }
         public Azure.Core.Amqp.AmqpMessageProperties Properties { get { throw null; } }
+        public bool HasSection(Azure.Core.Amqp.AmqpMessageSection section) { throw null; }
     }
     public partial class AmqpMessageBody
     {
@@ -87,4 +88,14 @@ internal AmqpMessageProperties() { }
         public Azure.Core.Amqp.AmqpAddress? To { get { throw null; } set { } }
         public System.ReadOnlyMemory<byte>? UserId { get { throw null; } set { } }
     }
+    public enum AmqpMessageSection
+    {
+        Header = 0,
+        DeliveryAnnotations = 1,
+        MessageAnnotations = 2,
+        Properties = 3,
+        ApplicationProperties = 4,
+        Body = 5,
+        Footer = 6,
+    }
 }

sdk/core/Azure.Core.Amqp/src/AmqpAnnotatedMessage.cs

@@ -27,7 +27,19 @@ public AmqpAnnotatedMessage(AmqpMessageBody body)
         /// Gets the header of the AMQP message.
         /// <seealso href="http://docs.oasis-open.org/amqp/core/v1.0/os/amqp-core-messaging-v1.0-os.html#type-header" />
         /// </summary>
-        public AmqpMessageHeader Header { get; } = new AmqpMessageHeader();
+        public AmqpMessageHeader Header
+        {
+            get
+            {
+                if (_header == null)
+                {
+                    _header = new AmqpMessageHeader();
+                }
+                return _header;
+            }
+        }
+
+        private AmqpMessageHeader? _header;
 
         /// <summary>
         /// Gets the footer of the AMQP message.
@@ -86,7 +98,19 @@ public IDictionary<string, object> MessageAnnotations
         /// <summary>
         /// Gets the properties of the AMQP message.
         /// </summary>
-        public AmqpMessageProperties Properties { get; } = new AmqpMessageProperties();
+        public AmqpMessageProperties Properties
+        {
+            get
+            {
+                if (_properties == null)
+                {
+                    _properties = new AmqpMessageProperties();
+                }
+                return _properties;
+            }
+        }
+
+        private AmqpMessageProperties? _properties;
 
         /// <summary>
         /// Gets the application properties of the AMQP message.
@@ -111,5 +135,23 @@ public IDictionary<string, object> ApplicationProperties
         /// <seealso href="http://docs.oasis-open.org/amqp/core/v1.0/os/amqp-core-messaging-v1.0-os.html#type-data"/>
         /// </summary>
         public AmqpMessageBody Body { get; set; }
+
+        /// <summary>
+        /// Determines whether the specified section is present for the AMQP message.
+        /// </summary>
+        /// <param name="section">The section to consider.</param>
+        /// <returns><c>true</c> if the specified <paramref name="section"/> is populated for the AMQP message; otherwise, <c>false</c>.</returns>
+        public bool HasSection(AmqpMessageSection section) =>
+            section switch
+            {
+                AmqpMessageSection.Header => (_header != null),
+                AmqpMessageSection.DeliveryAnnotations => (_deliveryAnnotations != null),
+                AmqpMessageSection.MessageAnnotations => (_messageAnnotations != null),
+                AmqpMessageSection.Properties => (_properties != null),
+                AmqpMessageSection.ApplicationProperties => (_applicationProperties != null),
+                AmqpMessageSection.Body => (Body != null),
+                AmqpMessageSection.Footer => (_footer != null),
+                _ => throw new ArgumentException($"Unknown AMQP message section: { section }.", nameof(section))
+            };
     }
 }

sdk/core/Azure.Core.Amqp/src/AmqpMessageSection.cs

@@ -0,0 +1,56 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+namespace Azure.Core.Amqp
+{
+    /// <summary>
+    /// Represents the sections of an AMQP message.
+    /// <seealso href="http://docs.oasis-open.org/amqp/core/v1.0/os/amqp-core-messaging-v1.0-os.html#section-message-format"/>
+    /// </summary>
+    public enum AmqpMessageSection
+    {
+        /// <summary>
+        /// The header section of the message.
+        /// <seealso href="http://docs.oasis-open.org/amqp/core/v1.0/os/amqp-core-messaging-v1.0-os.html#type-header"/>
+        /// <seealso cref="AmqpMessageHeader" />
+        /// </summary>
+        Header,
+
+        /// <summary>
+        /// The delivery annotations section of the message.
+        /// <seealso href="http://docs.oasis-open.org/amqp/core/v1.0/os/amqp-core-messaging-v1.0-os.html#type-delivery-annotations"/>
+        /// </summary>
+        DeliveryAnnotations,
+
+        /// <summary>
+        /// The message annotations section of the message.
+        /// <seealso href="http://docs.oasis-open.org/amqp/core/v1.0/os/amqp-core-messaging-v1.0-os.html#type-message-annotations"/>
+        /// </summary>
+        MessageAnnotations,
+
+        /// <summary>
+        /// The properties section of the message.
+        /// <seealso href="http://docs.oasis-open.org/amqp/core/v1.0/os/amqp-core-messaging-v1.0-os.html#type-properties"/>
+        /// <seealso cref="AmqpMessageProperties"/>
+        /// </summary>
+        Properties,
+
+        /// <summary>
+        /// The application properties section of the message.
+        /// <seealso href="http://docs.oasis-open.org/amqp/core/v1.0/os/amqp-core-messaging-v1.0-os.html#type-application-properties"/>
+        /// </summary>
+        ApplicationProperties,
+
+        /// <summary>
+        /// The body of the message, representing one specific <see cref="AmqpMessageBodyType" /> sections.
+        /// <seealso cref="AmqpMessageBody"/>
+        /// </summary>
+        Body,
+
+        /// <summary>
+        /// The footer section of the message.
+        /// <seealso href="http://docs.oasis-open.org/amqp/core/v1.0/os/amqp-core-messaging-v1.0-os.html#type-footer"/>
+        /// </summary>
+        Footer
+    }
+}

sdk/core/Azure.Core.Amqp/tests/AmqpAnnotatedMessageTests.cs

@@ -11,6 +11,8 @@ namespace Azure.Core.Amqp.Tests
 {
     public class AmqpAnnotatedMessageTests
     {
+        private static readonly AmqpMessageBody EmptyDataBody = AmqpMessageBody.FromData(new ReadOnlyMemory<byte>[] { Array.Empty<byte>() });
+
         [Test]
         public void CanCreateAnnotatedMessage()
         {
@@ -65,5 +67,92 @@ public void CanCreateAnnotatedMessage()
             Assert.AreEqual("to", message.Properties.To.ToString());
             Assert.AreEqual("userId", Encoding.UTF8.GetString(message.Properties.UserId.Value.ToArray()));
         }
+
+        [Test]
+        public void HeaderIsCreatedOnDemand()
+        {
+            var message = new AmqpAnnotatedMessage(EmptyDataBody);
+            Assert.False(message.HasSection(AmqpMessageSection.Header));
+
+            message.Header.DeliveryCount = 99;
+            Assert.True(message.HasSection(AmqpMessageSection.Header));
+            Assert.NotNull(message.Header);
+        }
+
+        [Test]
+        public void DeliveryAnnotationsAreCreatedOnDemand()
+        {
+            var message = new AmqpAnnotatedMessage(EmptyDataBody);
+            Assert.False(message.HasSection(AmqpMessageSection.DeliveryAnnotations));
+
+            message.DeliveryAnnotations.Add("test", new object());
+            Assert.True(message.HasSection(AmqpMessageSection.DeliveryAnnotations));
+            Assert.NotNull(message.DeliveryAnnotations);
+        }
+
+        [Test]
+        public void MessageAnnotationsAreCreatedOnDemand()
+        {
+            var message = new AmqpAnnotatedMessage(EmptyDataBody);
+            Assert.False(message.HasSection(AmqpMessageSection.MessageAnnotations));
+
+            message.MessageAnnotations.Add("test", new object());
+            Assert.True(message.HasSection(AmqpMessageSection.MessageAnnotations));
+            Assert.NotNull(message.MessageAnnotations);
+        }
+
+        [Test]
+        public void PropertiesAreCreatedOnDemand()
+        {
+            var message = new AmqpAnnotatedMessage(EmptyDataBody);
+            Assert.False(message.HasSection(AmqpMessageSection.Properties));
+
+            message.Properties.ContentType = "test/unit";
+            Assert.True(message.HasSection(AmqpMessageSection.Properties));
+            Assert.NotNull(message.Properties);
+        }
+
+        [Test]
+        public void ApplicationPropertiesAreCreatedOnDemand()
+        {
+            var message = new AmqpAnnotatedMessage(EmptyDataBody);
+            Assert.False(message.HasSection(AmqpMessageSection.ApplicationProperties));
+
+            message.ApplicationProperties.Add("test", new object());
+            Assert.True(message.HasSection(AmqpMessageSection.ApplicationProperties));
+            Assert.NotNull(message.ApplicationProperties);
+        }
+
+        [Test]
+        public void FooterIsCreatedOnDemand()
+        {
+            var message = new AmqpAnnotatedMessage(EmptyDataBody);
+            Assert.False(message.HasSection(AmqpMessageSection.Footer));
+
+            message.Footer.Add("test", new object());
+            Assert.True(message.HasSection(AmqpMessageSection.Footer));
+            Assert.NotNull(message.Footer);
+        }
+
+        [Test]
+        public void BodyIsDetectedByHasSection()
+        {
+            var message = new AmqpAnnotatedMessage(EmptyDataBody);
+
+            message.Body = null;
+            Assert.False(message.HasSection(AmqpMessageSection.Body));
+
+            message.Body = AmqpMessageBody.FromValue("this is a string value");
+            Assert.True(message.HasSection(AmqpMessageSection.Body));
+        }
+
+        [Test]
+        public void HasSectionValidatesTheSection()
+        {
+            var invalidSection = (AmqpMessageSection)int.MinValue;
+            var message = new AmqpAnnotatedMessage(EmptyDataBody);
+
+            Assert.Throws<ArgumentException>(() => message.HasSection(invalidSection));
+        }
     }
 }