[Group 4] Enable nullable annotations for `Microsoft.Extensions.Logging.EventSource` (#66802)

* Annotate src

* Annotate ref

* Make internal parameters non-nullable if they never receive null

src/libraries/Microsoft.Extensions.Logging.EventSource/ref/Microsoft.Extensions.Logging.EventSource.csproj

 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <TargetFrameworks>$(NetCoreAppCurrent);$(NetCoreAppMinimum);netstandard2.0;$(NetFrameworkMinimum)</TargetFrameworks>
+    <Nullable>enable</Nullable>
   </PropertyGroup>
 
   <ItemGroup>

src/libraries/Microsoft.Extensions.Logging.EventSource/src/EventLogFiltersConfigureOptionsChangeSource.cs

@@ -7,7 +7,7 @@
 
 namespace Microsoft.Extensions.Logging
 {
-    internal sealed class EventLogFiltersConfigureOptionsChangeSource: IOptionsChangeTokenSource<LoggerFilterOptions>
+    internal sealed class EventLogFiltersConfigureOptionsChangeSource : IOptionsChangeTokenSource<LoggerFilterOptions>
     {
         private readonly LoggingEventSource _eventSource;
 
@@ -18,6 +18,6 @@ public EventLogFiltersConfigureOptionsChangeSource(LoggingEventSource eventSourc
 
         public IChangeToken GetChangeToken() => _eventSource.GetFilterChangeToken();
 
-        public string Name { get; }
+        public string? Name { get; }
     }
 }

src/libraries/Microsoft.Extensions.Logging.EventSource/src/EventSourceLogger.cs

@@ -26,7 +26,7 @@ internal sealed class EventSourceLogger : ILogger
         private readonly LoggingEventSource _eventSource;
         private readonly int _factoryID;
 
-        public EventSourceLogger(string categoryName, int factoryID, LoggingEventSource eventSource, EventSourceLogger next)
+        public EventSourceLogger(string categoryName, int factoryID, LoggingEventSource eventSource, EventSourceLogger? next)
         {
             CategoryName = categoryName;
 
@@ -43,20 +43,20 @@ public EventSourceLogger(string categoryName, int factoryID, LoggingEventSource
         public LogLevel Level { get; set; }
 
         // Loggers created by a single provider form a linked list
-        public EventSourceLogger Next { get; }
+        public EventSourceLogger? Next { get; }
 
         public bool IsEnabled(LogLevel logLevel)
         {
             return logLevel != LogLevel.None && logLevel >= Level;
         }
 
-        public void Log<TState>(LogLevel logLevel, EventId eventId, TState state, Exception exception, Func<TState, Exception, string> formatter)
+        public void Log<TState>(LogLevel logLevel, EventId eventId, TState state, Exception? exception, Func<TState, Exception?, string> formatter)
         {
             if (!IsEnabled(logLevel))
             {
                 return;
             }
-            string message = null;
+            string? message = null;
 
             // See if they want the formatted message
             if (_eventSource.IsEnabled(EventLevel.Critical, LoggingEventSource.Keywords.FormattedMessage))
@@ -75,7 +75,7 @@ public void Log<TState>(LogLevel logLevel, EventId eventId, TState state, Except
             if (_eventSource.IsEnabled(EventLevel.Critical, LoggingEventSource.Keywords.Message))
             {
                 ExceptionInfo exceptionInfo = GetExceptionInfo(exception);
-                IReadOnlyList<KeyValuePair<string, string>> arguments = GetProperties(state);
+                IReadOnlyList<KeyValuePair<string, string?>> arguments = GetProperties(state);
 
                 _eventSource.Message(
                     logLevel,
@@ -94,16 +94,16 @@ public void Log<TState>(LogLevel logLevel, EventId eventId, TState state, Except
                 if (exception != null)
                 {
                     ExceptionInfo exceptionInfo = GetExceptionInfo(exception);
-                    KeyValuePair<string, string>[] exceptionInfoData = new[]
+                    KeyValuePair<string, string?>[] exceptionInfoData = new[]
                     {
-                        new KeyValuePair<string, string>("TypeName", exceptionInfo.TypeName),
-                        new KeyValuePair<string, string>("Message", exceptionInfo.Message),
-                        new KeyValuePair<string, string>("HResult", exceptionInfo.HResult.ToString()),
-                        new KeyValuePair<string, string>("VerboseMessage", exceptionInfo.VerboseMessage),
+                        new KeyValuePair<string, string?>("TypeName", exceptionInfo.TypeName),
+                        new KeyValuePair<string, string?>("Message", exceptionInfo.Message),
+                        new KeyValuePair<string, string?>("HResult", exceptionInfo.HResult.ToString()),
+                        new KeyValuePair<string, string?>("VerboseMessage", exceptionInfo.VerboseMessage),
                     };
                     exceptionJson = ToJson(exceptionInfoData);
                 }
-                IReadOnlyList<KeyValuePair<string, string>> arguments = GetProperties(state);
+                IReadOnlyList<KeyValuePair<string, string?>> arguments = GetProperties(state);
                 message ??= formatter(state, exception);
                 _eventSource.MessageJson(
                     logLevel,
@@ -129,7 +129,7 @@ public IDisposable BeginScope<TState>(TState state)
             // If JsonMessage is on, use JSON format
             if (_eventSource.IsEnabled(EventLevel.Critical, LoggingEventSource.Keywords.JsonMessage))
             {
-                IReadOnlyList<KeyValuePair<string, string>> arguments = GetProperties(state);
+                IReadOnlyList<KeyValuePair<string, string?>> arguments = GetProperties(state);
                 _eventSource.ActivityJsonStart(id, _factoryID, CategoryName, ToJson(arguments));
                 return new ActivityScope(_eventSource, CategoryName, id, _factoryID, true);
             }
@@ -137,7 +137,7 @@ public IDisposable BeginScope<TState>(TState state)
             if (_eventSource.IsEnabled(EventLevel.Critical, LoggingEventSource.Keywords.Message) ||
                 _eventSource.IsEnabled(EventLevel.Critical, LoggingEventSource.Keywords.FormattedMessage))
             {
-                IReadOnlyList<KeyValuePair<string, string>> arguments = GetProperties(state);
+                IReadOnlyList<KeyValuePair<string, string?>> arguments = GetProperties(state);
                 _eventSource.ActivityStart(id, _factoryID, CategoryName, arguments);
                 return new ActivityScope(_eventSource, CategoryName, id, _factoryID, false);
             }
@@ -185,7 +185,7 @@ public void Dispose()
         /// <param name="exception">The exception to get information for.</param>
         /// <returns>ExceptionInfo object represending a .NET Exception</returns>
         /// <remarks>ETW does not support a concept of a null value. So we use an un-initialized object if there is no exception in the event data.</remarks>
-        private ExceptionInfo GetExceptionInfo(Exception exception)
+        private ExceptionInfo GetExceptionInfo(Exception? exception)
         {
             return exception != null ? new ExceptionInfo(exception) : ExceptionInfo.Empty;
         }
@@ -193,29 +193,29 @@ private ExceptionInfo GetExceptionInfo(Exception exception)
         /// <summary>
         /// Converts an ILogger state object into a set of key-value pairs (That can be send to a EventSource)
         /// </summary>
-        private IReadOnlyList<KeyValuePair<string, string>> GetProperties(object state)
+        private IReadOnlyList<KeyValuePair<string, string?>> GetProperties(object? state)
         {
-            if (state is IReadOnlyList<KeyValuePair<string, object>> keyValuePairs)
+            if (state is IReadOnlyList<KeyValuePair<string, object?>> keyValuePairs)
             {
-                var arguments = new KeyValuePair<string, string>[keyValuePairs.Count];
+                var arguments = new KeyValuePair<string, string?>[keyValuePairs.Count];
                 for (int i = 0; i < keyValuePairs.Count; i++)
                 {
-                    KeyValuePair<string, object> keyValuePair = keyValuePairs[i];
-                    arguments[i] = new KeyValuePair<string, string>(keyValuePair.Key, keyValuePair.Value?.ToString());
+                    KeyValuePair<string, object?> keyValuePair = keyValuePairs[i];
+                    arguments[i] = new KeyValuePair<string, string?>(keyValuePair.Key, keyValuePair.Value?.ToString());
                 }
                 return arguments;
             }
 
-            return Array.Empty<KeyValuePair<string, string>>();
+            return Array.Empty<KeyValuePair<string, string?>>();
         }
 
-        private string ToJson(IReadOnlyList<KeyValuePair<string, string>> keyValues)
+        private string ToJson(IReadOnlyList<KeyValuePair<string, string?>> keyValues)
         {
             using var stream = new MemoryStream();
             using var writer = new Utf8JsonWriter(stream);
 
             writer.WriteStartObject();
-            foreach (KeyValuePair<string, string> keyValue in keyValues)
+            foreach (KeyValuePair<string, string?> keyValue in keyValues)
             {
                 writer.WriteString(keyValue.Key, keyValue.Value);
             }
@@ -228,7 +228,7 @@ private string ToJson(IReadOnlyList<KeyValuePair<string, string>> keyValues)
                 buffer = new ArraySegment<byte>(stream.ToArray());
             }
 
-            return Encoding.UTF8.GetString(buffer.Array, buffer.Offset, buffer.Count);
+            return Encoding.UTF8.GetString(buffer.Array!, buffer.Offset, buffer.Count);
         }
     }
 }

src/libraries/Microsoft.Extensions.Logging.EventSource/src/EventSourceLoggerProvider.cs

@@ -17,7 +17,7 @@ public class EventSourceLoggerProvider : ILoggerProvider
         // A small integer that uniquely identifies the LoggerFactory associated with this LoggingProvider.
         private readonly int _factoryID;
 
-        private EventSourceLogger _loggers; // Linked list of loggers that I have created
+        private EventSourceLogger? _loggers; // Linked list of loggers that I have created
         private readonly LoggingEventSource _eventSource;
 
         public EventSourceLoggerProvider(LoggingEventSource eventSource!!)
@@ -36,7 +36,7 @@ public ILogger CreateLogger(string categoryName)
         public void Dispose()
         {
             // Turn off any logging
-            for (EventSourceLogger logger = _loggers; logger != null; logger = logger.Next)
+            for (EventSourceLogger? logger = _loggers; logger != null; logger = logger.Next)
             {
                 logger.Level = LogLevel.None;
             }

src/libraries/Microsoft.Extensions.Logging.EventSource/src/ExceptionInfo.cs

@@ -8,7 +8,7 @@ namespace Microsoft.Extensions.Logging.EventSource
     /// <summary>
     /// Represents information about exceptions that is captured by EventSourceLogger
     /// </summary>
-    [System.Diagnostics.Tracing.EventData(Name ="ExceptionInfo")]
+    [System.Diagnostics.Tracing.EventData(Name = "ExceptionInfo")]
     internal sealed class ExceptionInfo
     {
         public static ExceptionInfo Empty { get; } = new ExceptionInfo();
@@ -25,9 +25,9 @@ public ExceptionInfo(Exception exception)
             VerboseMessage = exception.ToString();
         }
 
-        public string TypeName { get; }
-        public string Message { get; }
+        public string? TypeName { get; }
+        public string? Message { get; }
         public int HResult { get; }
-        public string VerboseMessage { get; } // This is the ToString() of the Exception
+        public string? VerboseMessage { get; } // This is the ToString() of the Exception
     }
 }

src/libraries/Microsoft.Extensions.Logging.EventSource/src/LoggingEventSource.cs

@@ -113,7 +113,7 @@ public static class Keywords
         // base ctor might call OnEventCommand and set filter spec
         // having assignment in ctor would overwrite the value
         private LoggerFilterRule[] _filterSpec = Array.Empty<LoggerFilterRule>();
-        private CancellationTokenSource _cancellationTokenSource;
+        private CancellationTokenSource? _cancellationTokenSource;
         private const string UseAppFilters = "UseAppFilters";
         private const string WriteEventCoreSuppressionJustification = "WriteEventCore is safe when eventData object is a primitive type which is in this case.";
         private const string WriteEventDynamicDependencySuppressionJustification = "DynamicDependency attribute will ensure that the required properties are not trimmed.";
@@ -129,7 +129,7 @@ private LoggingEventSource() : base(EventSourceSettings.EtwSelfDescribingEventFo
         [Event(1, Keywords = Keywords.FormattedMessage, Level = EventLevel.LogAlways)]
         [UnconditionalSuppressMessage("ReflectionAnalysis", "IL2026:RequiresUnreferencedCode",
             Justification = WriteEventCoreSuppressionJustification)]
-        internal unsafe void FormattedMessage(LogLevel Level, int FactoryID, string LoggerName, int EventId, string EventName, string FormattedMessage)
+        internal unsafe void FormattedMessage(LogLevel Level, int FactoryID, string LoggerName, int EventId, string? EventName, string FormattedMessage)
         {
             if (IsEnabled())
             {
@@ -164,7 +164,7 @@ internal unsafe void FormattedMessage(LogLevel Level, int FactoryID, string Logg
         [DynamicDependency(DynamicallyAccessedMemberTypes.PublicProperties, typeof(KeyValuePair<string, string>))]
         [UnconditionalSuppressMessage("ReflectionAnalysis", "IL2026:RequiresUnreferencedCode",
             Justification = WriteEventDynamicDependencySuppressionJustification)]
-        internal void Message(LogLevel Level, int FactoryID, string LoggerName, int EventId, string EventName, ExceptionInfo Exception, IEnumerable<KeyValuePair<string, string>> Arguments)
+        internal void Message(LogLevel Level, int FactoryID, string LoggerName, int EventId, string? EventName, ExceptionInfo Exception, IEnumerable<KeyValuePair<string, string?>> Arguments)
         {
             if (IsEnabled())
             {
@@ -179,7 +179,7 @@ internal void Message(LogLevel Level, int FactoryID, string LoggerName, int Even
         [DynamicDependency(DynamicallyAccessedMemberTypes.PublicProperties, typeof(KeyValuePair<string, string>))]
         [UnconditionalSuppressMessage("ReflectionAnalysis", "IL2026:RequiresUnreferencedCode",
             Justification = WriteEventDynamicDependencySuppressionJustification)]
-        internal void ActivityStart(int ID, int FactoryID, string LoggerName, IEnumerable<KeyValuePair<string, string>> Arguments)
+        internal void ActivityStart(int ID, int FactoryID, string LoggerName, IEnumerable<KeyValuePair<string, string?>> Arguments)
         {
             if (IsEnabled())
             {
@@ -213,7 +213,7 @@ internal unsafe void ActivityStop(int ID, int FactoryID, string LoggerName)
         [Event(5, Keywords = Keywords.JsonMessage, Level = EventLevel.LogAlways)]
         [UnconditionalSuppressMessage("ReflectionAnalysis", "IL2026:RequiresUnreferencedCode",
             Justification = WriteEventCoreSuppressionJustification)]
-        internal unsafe void MessageJson(LogLevel Level, int FactoryID, string LoggerName, int EventId, string EventName, string ExceptionJson, string ArgumentsJson, string FormattedMessage)
+        internal unsafe void MessageJson(LogLevel Level, int FactoryID, string LoggerName, int EventId, string? EventName, string ExceptionJson, string ArgumentsJson, string FormattedMessage)
         {
             if (IsEnabled())
             {
@@ -298,9 +298,9 @@ internal unsafe void ActivityJsonStop(int ID, int FactoryID, string LoggerName)
         /// <inheritdoc />
         protected override void OnEventCommand(EventCommandEventArgs command)
         {
-            if (command.Command == EventCommand.Update || command.Command == EventCommand.Enable)
+            if (command.Command is EventCommand.Update or EventCommand.Enable)
             {
-                if (!command.Arguments.TryGetValue("FilterSpecs", out string filterSpec))
+                if (!command.Arguments!.TryGetValue("FilterSpecs", out string? filterSpec))
                 {
                     filterSpec = string.Empty; // This means turn on everything.
                 }
@@ -318,7 +318,7 @@ protected override void OnEventCommand(EventCommandEventArgs command)
         /// </summary>
         /// <param name="filterSpec">The filter specification to set.</param>
         [NonEvent]
-        private void SetFilterSpec(string filterSpec)
+        private void SetFilterSpec(string? filterSpec)
         {
             _filterSpec = ParseFilterSpec(filterSpec, GetDefaultLevel());
 
@@ -335,7 +335,7 @@ internal IChangeToken GetFilterChangeToken()
         [NonEvent]
         private void FireChangeToken()
         {
-            CancellationTokenSource tcs = Interlocked.Exchange(ref _cancellationTokenSource, null);
+            CancellationTokenSource? tcs = Interlocked.Exchange(ref _cancellationTokenSource, null);
             tcs?.Cancel();
         }
 
@@ -351,7 +351,7 @@ private void FireChangeToken()
         /// The first specification that 'loggers' Name matches is used.
         /// </summary>
         [NonEvent]
-        private static LoggerFilterRule[] ParseFilterSpec(string filterSpec, LogLevel defaultLevel)
+        private static LoggerFilterRule[] ParseFilterSpec(string? filterSpec, LogLevel defaultLevel)
         {
             if (filterSpec == string.Empty)
             {
@@ -501,7 +501,7 @@ private static unsafe void SetEventData<T>(ref EventData eventData, ref T value,
         {
             if (typeof(T) == typeof(string))
             {
-                string str = value as string;
+                string str = (value as string)!;
 #if DEBUG
                 fixed (char* rePinnedString = str)
                 {

src/libraries/Microsoft.Extensions.Logging.EventSource/src/Microsoft.Extensions.Logging.EventSource.csproj

@@ -2,6 +2,7 @@
 
   <PropertyGroup>
     <TargetFrameworks>$(NetCoreAppCurrent);$(NetCoreAppMinimum);netstandard2.0;$(NetFrameworkMinimum)</TargetFrameworks>
+    <Nullable>enable</Nullable>
     <EnableDefaultItems>true</EnableDefaultItems>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <!-- Use targeting pack references instead of granular ones in the project file. -->