Serilog dupe stackframe fix (#1076)

* Checks if the log message is a duplicate using StackFrames

* Handle additional stackframe case

* Adds Serilog Asp.NET Core integration test covering duplicate log event

* Update CHANGELOG.md

src/Agent/CHANGELOG.md

@@ -5,6 +5,10 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased] changes
+
+### APM logs in context
+Automatic application log forwarding is now enabled by default. This version of the agent will automatically send enriched application logs to New Relic. To learn more about about this feature see [here](https://docs.newrelic.com/docs/apm/new-relic-apm/getting-started/get-started-logs-context/), and additional configuration options are available [here](https://docs.newrelic.com/docs/logs/logs-context/net-configure-logs-context-all). To learn about how to toggle log ingestion on or off by account see [here](https://docs.newrelic.com/docs/logs/logs-context/disable-automatic-logging).
+
 ### New Features
 * Error messages in error traces and error events now retain up to 1023 characters instead of 255 characters. [#1058](https://github.com/newrelic/newrelic-dotnet-agent/pull/1058)
 * New environment variables have been added for AllowAllHeaders and Attributes configuration settings. See our [documentation](https://docs.newrelic.com/docs/apm/agents/net-agent/configuration/net-agent-configuration/#optional-environment-variables) for more details. [#1059](https://github.com/newrelic/newrelic-dotnet-agent/pull/1059)
@@ -14,6 +18,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Fixes
 * Fixes Agent fails to execute explain plan for parameterized stored procedure. ([#1066](https://github.com/newrelic/newrelic-dotnet-agent/pull/1066)) 
+* Fixes getting duplicate logs using log forwarding and Serilog. [#1076](https://github.com/newrelic/newrelic-dotnet-agent/pull/1076)
+
+### Deprecations
+Microsoft has officially EOL .NET Framework versions 4.5.1, 4.5.2, and 4.6.1 on  Apr 26, 2022.
+The informational blog can be found [here](https://devblogs.microsoft.com/dotnet/net-framework-4-5-2-4-6-4-6-1-will-reach-end-of-support-on-april-26-2022).  The official product lifecycle start and end dates can be found [here](https://docs.microsoft.com/en-us/lifecycle/products/microsoft-net-framework).  The dotnet agent support of these framework versions is will continue as is with the released versions.  In a future major release, we will target .NET framework 4.6.2 onwards.
 
 ## [9.7.1] - 2022-04-13
 ### Fixes

src/Agent/NewRelic/Agent/Extensions/Providers/Wrapper/Logging/SerilogWrapper.cs

@@ -24,6 +24,7 @@ public class SerilogWrapper : IWrapper
         public bool IsTransactionRequired => false;
 
         private const string WrapperName = "serilog";
+        private const string DispatchName = "Dispatch";
 
         public CanWrapResponse CanWrap(InstrumentedMethodInfo methodInfo)
         {
@@ -37,6 +38,29 @@ public CanWrapResponse CanWrap(InstrumentedMethodInfo methodInfo)
 
         public AfterWrappedMethodDelegate BeforeWrappedMethod(InstrumentedMethodCall instrumentedMethodCall, IAgent agent, ITransaction transaction)
         {
+            // This block works around an issue we are seeing in Serilog where Dispatch is called up to 3 times for each log message
+            // When looking at a stack trace for the problem, the you will see up to 3 Dispatch methods one after the other
+            // This detects the duplicates and noops.
+            var frame7 = new System.Diagnostics.StackFrame(7, false).GetMethod().Name;
+            string potentialDispatchFrame;
+            if (frame7 != DispatchName)
+            {
+                // Frame 7 is not Dispatch. This means that an extra frame was in the stack called "UnsafeInvokeInternal" at frame 6
+                // Look at frame 9 for duplicates instead of at frame 8
+                potentialDispatchFrame = new System.Diagnostics.StackFrame(9, false).GetMethod().Name;
+            }
+            else
+            {
+                // Frame 7 is Dispatch, no extra frames
+                // Look at frame 8 for duplicates
+                potentialDispatchFrame = new System.Diagnostics.StackFrame(8, false).GetMethod().Name;
+            }
+
+            if (potentialDispatchFrame == DispatchName)
+            {
+                return Delegates.NoOp;
+            }
+
             var logEvent = instrumentedMethodCall.MethodCall.MethodArguments[0];
 
             RecordLogMessage(logEvent, agent);

tests/Agent/IntegrationTests/IntegrationTests/Logging/Common.cs

@@ -7,6 +7,7 @@ public enum LoggingFramework
     {
         Log4net,
         Serilog,
-        MicrosoftLogging
+        MicrosoftLogging,
+        SerilogWeb
     }
 }