Developers can employ EventSource APIs when publishing for AOT targets to be able to use .NET tracing capabilities

EventSource is a common logging abstraction in .NET but it uses reflection to generate the schema for an EventSource definition. The source generator would do this at build time and make using EventSources reflection free.

EventSource used to have a hookup point for this that was used in .NET Native. It looked like this:

runtime/src/libraries/System.Private.CoreLib/src/System/Diagnostics/Tracing/EventSource.cs

Lines 646 to 663 in dbcea6b

    
           internal virtual void GetMetadata(out Guid eventSourceGuid, out string eventSourceName, out EventMetadata[] eventData, out byte[] manifestBytes) 
        
           { 
        
               // 
        
               // In ProjectN subclasses need to override this method, and return the data from their EventSourceAttribute and EventAttribute annotations. 
        
               // On other architectures it is a no-op. 
        
               // 
        
               // eventDescriptors needs to contain one EventDescriptor for each event; the event's ID should be the same as its index in this array. 
        
               // manifestBytes is a UTF-8 encoding of the ETW manifest for the type. 
        
               // 
        
               // This will be implemented by an IL rewriter, so we can't make this method abstract or the initial build of the subclass would fail. 
        
               // 
        
               eventSourceGuid = Guid.Empty; 
        
               eventSourceName = null; 
        
               eventData = null; 
        
               manifestBytes = null; 
        
               return; 
        
           }

It was nuked in the meantime (latest sources don't have it anymore).

How would this be consumed by non C# languages?

A whole lot of startup going into generating EventSource manifests and Guids etc for a standardish ASP.NET Core app with ApplicationInsights, e.g. this is https://themesof.net/

Couldn't fit it all on one screen, here's the rest

For https://themesof.net/ looks like 27 EventSources are created on startup, most of them probably just to check .Log.IsEnabled() and get false back... 😅

With any not in System.Private.CoreLib.dll doing reflection to get the Guid to use

It is an issue for PowerShell startup too.

@LakshanF

@LakshanF @davmason do you know of any unresolved issues related to using EventSource on NativeAOT?

Any payload that uses complex data types in EventSource, that in turn depends on unbound reflection for serialization, will be problematic for NativeAOT applications (primarily due to trimming). The long-term solution is to use a source generator for such cases. These scenarios would cause both Roslyn analyzer (when the application project file indicate intention to use NativeAOT) and ILCompiler to generate warnings, and developers should not ignore these warnings.

All Framework EventSource providers should work without problems, as well as payloads with primitive data types.

Navigation Menu

Repository navigation

Developers can employ EventSource APIs when publishing for AOT targets to be able to use .NET tracing capabilities #43390

6 remaining items

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

	internal virtual void GetMetadata(out Guid eventSourceGuid, out string eventSourceName, out EventMetadata[] eventData, out byte[] manifestBytes)
	{
	//
	// In ProjectN subclasses need to override this method, and return the data from their EventSourceAttribute and EventAttribute annotations.
	// On other architectures it is a no-op.
	//
	// eventDescriptors needs to contain one EventDescriptor for each event; the event's ID should be the same as its index in this array.
	// manifestBytes is a UTF-8 encoding of the ETW manifest for the type.
	//
	// This will be implemented by an IL rewriter, so we can't make this method abstract or the initial build of the subclass would fail.
	//
	eventSourceGuid = Guid.Empty;
	eventSourceName = null;
	eventData = null;
	manifestBytes = null;

	return;
	}

Developers can employ EventSource APIs when publishing for AOT targets to be able to use .NET tracing capabilities #43390

Description

Activity

MichalStrehovsky commented on Oct 14, 2020

7sharp9 commented on Nov 17, 2020

6 remaining items

benaadams commented on Mar 10, 2021

benaadams commented on Mar 10, 2021

iSazonov commented on Mar 10, 2021

tommcdon commented on Jul 23, 2023

LakshanF commented on Jul 23, 2023

Metadata

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

Issue actions