Reduce allocations caused by logging.

src/Avalonia.Base/AvaloniaObject.cs

@@ -326,8 +326,6 @@ namespace Avalonia
 
             VerifyAccess();
 
-            var description = GetDescription(source);
-
             if (property.IsDirect)
             {
                 if (property.IsReadOnly)
@@ -335,12 +333,18 @@ namespace Avalonia
                     throw new ArgumentException($"The property {property.Name} is readonly.");
                 }
 
-                Logger.Verbose(
-                    LogArea.Property, 
-                    this,
-                    "Bound {Property} to {Binding} with priority LocalValue", 
-                    property, 
-                    description);
+                if (Logger.IsEnabled(LogEventLevel.Verbose))
+                {
+                    var description = GetDescription(source);
+
+                    Logger.Log(
+                        LogEventLevel.Verbose,
+                        LogArea.Property,
+                        this,
+                        "Bound {Property} to {Binding} with priority LocalValue",
+                        property,
+                        description);
+                }
 
                 if (_directBindings == null)
                 {
@@ -351,13 +355,19 @@ namespace Avalonia
             }
             else
             {
-                Logger.Verbose(
-                    LogArea.Property,
-                    this,
-                    "Bound {Property} to {Binding} with priority {Priority}",
-                    property,
-                    description,
-                    priority);
+                if (Logger.IsEnabled(LogEventLevel.Verbose))
+                {
+                    var description = GetDescription(source);
+
+                    Logger.Log(
+                        LogEventLevel.Verbose,
+                        LogArea.Property,
+                        this,
+                        "Bound {Property} to {Binding} with priority {Priority}",
+                        property,
+                        description,
+                        priority);
+                }
 
                 return Values.AddBinding(property, source, priority);
             }
@@ -406,14 +416,18 @@ namespace Avalonia
             {
                 RaisePropertyChanged(property, oldValue, newValue, (BindingPriority)priority);
 
-                Logger.Verbose(
-                    LogArea.Property,
-                    this,
-                    "{Property} changed from {$Old} to {$Value} with priority {Priority}",
-                    property,
-                    oldValue,
-                    newValue,
-                    (BindingPriority)priority);
+                if (Logger.IsEnabled(LogEventLevel.Verbose))
+                {
+                    Logger.Log(
+                        LogEventLevel.Verbose,
+                        LogArea.Property,
+                        this,
+                        "{Property} changed from {$Old} to {$Value} with priority {Priority}",
+                        property,
+                        oldValue,
+                        newValue,
+                        (BindingPriority)priority);
+                }
             }
         }
         
@@ -812,7 +826,13 @@ namespace Avalonia
         /// <param name="priority">The priority.</param>
         private void LogPropertySet(AvaloniaProperty property, object value, BindingPriority priority)
         {
-            Logger.Verbose(
+            if (!Logger.IsEnabled(LogEventLevel.Verbose))
+            {
+                return;
+            }
+
+            Logger.Log(
+                LogEventLevel.Verbose,
                 LogArea.Property,
                 this,
                 "Set {Property} to {$Value} with priority {Priority}",

src/Avalonia.Base/Logging/ILogSink.cs

@@ -8,6 +8,77 @@ namespace Avalonia.Logging
     /// </summary>
     public interface ILogSink
     {
+        /// <summary>
+        /// Checks if given log level is enabled.
+        /// </summary>
+        /// <param name="level">The log event level.</param>
+        /// <returns><see langword="true"/> if given log level is enabled.</returns>
+        bool IsEnabled(LogEventLevel level);
+
+        /// <summary>
+        /// Logs an event.
+        /// </summary>
+        /// <param name="level">The log event level.</param>
+        /// <param name="area">The area that the event originates.</param>
+        /// <param name="source">The object from which the event originates.</param>
+        /// <param name="messageTemplate">The message template.</param>
+        void Log(
+            LogEventLevel level,
+            string area,
+            object source,
+            string messageTemplate);
+
+        /// <summary>
+        /// Logs an event.
+        /// </summary>
+        /// <param name="level">The log event level.</param>
+        /// <param name="area">The area that the event originates.</param>
+        /// <param name="source">The object from which the event originates.</param>
+        /// <param name="messageTemplate">The message template.</param>
+        /// <param name="propertyValue0">Message property value.</param>
+        void Log<T0>(
+            LogEventLevel level,
+            string area,
+            object source,
+            string messageTemplate,
+            T0 propertyValue0);
+
+        /// <summary>
+        /// Logs an event.
+        /// </summary>
+        /// <param name="level">The log event level.</param>
+        /// <param name="area">The area that the event originates.</param>
+        /// <param name="source">The object from which the event originates.</param>
+        /// <param name="messageTemplate">The message template.</param>
+        /// <param name="propertyValue0">Message property value.</param>
+        /// <param name="propertyValue1">Message property value.</param>
+        void Log<T0, T1>(
+            LogEventLevel level,
+            string area,
+            object source,
+            string messageTemplate,
+            T0 propertyValue0,
+            T1 propertyValue1);
+
+        /// <summary>
+        /// Logs an event.
+        /// </summary>
+        /// <param name="level">The log event level.</param>
+        /// <param name="area">The area that the event originates.</param>
+        /// <param name="source">The object from which the event originates.</param>
+        /// <param name="messageTemplate">The message template.</param>
+        /// <param name="propertyValue0">Message property value.</param>
+        /// <param name="propertyValue1">Message property value.</param>
+        /// <param name="propertyValue2">Message property value.</param>
+        void Log<T0, T1, T2>(
+            LogEventLevel level,
+            string area,
+            object source,
+            string messageTemplate,
+            T0 propertyValue0,
+            T1 propertyValue1,
+            T2 propertyValue2);
+
         /// <summary>
         /// Logs a new event.
         /// </summary>

src/Avalonia.Base/Logging/Logger.cs

@@ -15,6 +15,96 @@ namespace Avalonia.Logging
         /// </summary>
         public static ILogSink Sink { get; set; }
 
+        /// <summary>
+        /// Checks if given log level is enabled.
+        /// </summary>
+        /// <param name="level">The log event level.</param>
+        /// <returns><see langword="true"/> if given log level is enabled.</returns>
+        public static bool IsEnabled(LogEventLevel level)
+        {
+            return Sink?.IsEnabled(level) == true;
+        }
+
+        /// <summary>
+        /// Logs an event.
+        /// </summary>
+        /// <param name="level">The log event level.</param>
+        /// <param name="area">The area that the event originates.</param>
+        /// <param name="source">The object from which the event originates.</param>
+        /// <param name="messageTemplate">The message template.</param>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static void Log(
+            LogEventLevel level,
+            string area,
+            object source,
+            string messageTemplate)
+        {
+            Sink?.Log(level, area, source, messageTemplate);
+        }
+
+        /// <summary>
+        /// Logs an event.
+        /// </summary>
+        /// <param name="level">The log event level.</param>
+        /// <param name="area">The area that the event originates.</param>
+        /// <param name="source">The object from which the event originates.</param>
+        /// <param name="messageTemplate">The message template.</param>
+        /// <param name="propertyValue0">Message property value.</param>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static void Log<T0>(
+            LogEventLevel level,
+            string area,
+            object source,
+            string messageTemplate,
+            T0 propertyValue0)
+        {
+            Sink?.Log(level, area, source, messageTemplate, propertyValue0);
+        }
+
+        /// <summary>
+        /// Logs an event.
+        /// </summary>
+        /// <param name="level">The log event level.</param>
+        /// <param name="area">The area that the event originates.</param>
+        /// <param name="source">The object from which the event originates.</param>
+        /// <param name="messageTemplate">The message template.</param>
+        /// <param name="propertyValue0">Message property value.</param>
+        /// <param name="propertyValue1">Message property value.</param>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static void Log<T0, T1>(
+            LogEventLevel level,
+            string area,
+            object source,
+            string messageTemplate,
+            T0 propertyValue0,
+            T1 propertyValue1)
+        {
+            Sink?.Log(level, area, source, messageTemplate, propertyValue0, propertyValue1);
+        }
+
+        /// <summary>
+        /// Logs an event.
+        /// </summary>
+        /// <param name="level">The log event level.</param>
+        /// <param name="area">The area that the event originates.</param>
+        /// <param name="source">The object from which the event originates.</param>
+        /// <param name="messageTemplate">The message template.</param>
+        /// <param name="propertyValue0">Message property value.</param>
+        /// <param name="propertyValue1">Message property value.</param>
+        /// <param name="propertyValue2">Message property value.</param>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static void Log<T0, T1, T2>(
+            LogEventLevel level,
+            string area,
+            object source,
+            string messageTemplate,
+            T0 propertyValue0,
+            T1 propertyValue1,
+            T2 propertyValue2)
+        {
+            Sink?.Log(level, area, source, messageTemplate, propertyValue0, propertyValue1, propertyValue2);
+        }
+
         /// <summary>
         /// Logs an event.
         /// </summary>

src/Avalonia.Controls/Primitives/TemplatedControl.cs

@@ -255,7 +255,7 @@ namespace Avalonia.Controls.Primitives
 
                 if (template != null)
                 {
-                    Logger.Verbose(LogArea.Control, this, "Creating control template");
+                    Logger.Log(LogEventLevel.Verbose, LogArea.Control, this, "Creating control template");
 
                     var (child, nameScope) = template.Build(this);
                     ApplyTemplatedParent(child);

src/Avalonia.Layout/LayoutManager.cs

@@ -2,6 +2,7 @@
 // Licensed under the MIT license. See licence.md file in the project root for full license information.
 
 using System;
+using System.Diagnostics;
 using Avalonia.Logging;
 using Avalonia.Threading;
 
@@ -69,15 +70,22 @@ namespace Avalonia.Layout
             {
                 _running = true;
 
-                Logger.Information(
-                    LogArea.Layout,
-                    this,
-                    "Started layout pass. To measure: {Measure} To arrange: {Arrange}",
-                    _toMeasure.Count,
-                    _toArrange.Count);
+                Stopwatch stopwatch = null;
 
-                var stopwatch = new System.Diagnostics.Stopwatch();
-                stopwatch.Start();
+                bool captureTiming = Logger.IsEnabled(LogEventLevel.Information);
+
+                if (captureTiming)
+                {
+                    Logger.Log(LogEventLevel.Information,
+                        LogArea.Layout,
+                        this,
+                        "Started layout pass. To measure: {Measure} To arrange: {Arrange}",
+                        _toMeasure.Count,
+                        _toArrange.Count);
+
+                    stopwatch = new Stopwatch();
+                    stopwatch.Start();
+                }
 
                 _toMeasure.BeginLoop(MaxPasses);
                 _toArrange.BeginLoop(MaxPasses);
@@ -103,8 +111,12 @@ namespace Avalonia.Layout
                 _toMeasure.EndLoop();
                 _toArrange.EndLoop();
 
-                stopwatch.Stop();
-                Logger.Information(LogArea.Layout, this, "Layout pass finished in {Time}", stopwatch.Elapsed);
+                if (captureTiming)
+                {
+                    stopwatch.Stop();
+
+                    Logger.Information(LogArea.Layout, this, "Layout pass finished in {Time}", stopwatch.Elapsed);
+                }
             }
 
             _queued = false;

src/Avalonia.Layout/Layoutable.cs

@@ -329,7 +329,7 @@ namespace Avalonia.Layout
                 DesiredSize = desiredSize;
                 _previousMeasure = availableSize;
 
-                Logger.Verbose(LogArea.Layout, this, "Measure requested {DesiredSize}", DesiredSize);
+                Logger.Log(LogEventLevel.Verbose, LogArea.Layout, this, "Measure requested {DesiredSize}", DesiredSize);
 
                 if (DesiredSize != previousDesiredSize)
                 {
@@ -356,7 +356,7 @@ namespace Avalonia.Layout
 
             if (!IsArrangeValid || _previousArrange != rect)
             {
-                Logger.Verbose(LogArea.Layout, this, "Arrange to {Rect} ", rect);
+                Logger.Log(LogEventLevel.Verbose, LogArea.Layout, this, "Arrange to {Rect} ", rect);
 
                 IsArrangeValid = true;
                 ArrangeCore(rect);
@@ -381,7 +381,7 @@ namespace Avalonia.Layout
         {
             if (IsMeasureValid)
             {
-                Logger.Verbose(LogArea.Layout, this, "Invalidated measure");
+                Logger.Log(LogEventLevel.Verbose, LogArea.Layout, this, "Invalidated measure");
 
                 IsMeasureValid = false;
                 IsArrangeValid = false;
@@ -402,7 +402,7 @@ namespace Avalonia.Layout
         {
             if (IsArrangeValid)
             {
-                Logger.Verbose(LogArea.Layout, this, "Invalidated arrange");
+                Logger.Log(LogEventLevel.Verbose, LogArea.Layout, this, "Invalidated arrange");
 
                 IsArrangeValid = false;
                 (VisualRoot as ILayoutRoot)?.LayoutManager?.InvalidateArrange(this);

src/Avalonia.Logging.Serilog/SerilogLogger.cs

@@ -34,6 +34,76 @@ namespace Avalonia.Logging.Serilog
             Logger.Sink = new SerilogLogger(output);
         }
 
+        public bool IsEnabled(LogEventLevel level)
+        {
+            return _output.IsEnabled((SerilogLogEventLevel)level);
+        }
+
+        public void Log(
+            LogEventLevel level,
+            string area,
+            object source,
+            string messageTemplate)
+        {
+            Contract.Requires<ArgumentNullException>(area != null);
+            Contract.Requires<ArgumentNullException>(messageTemplate != null);
+
+            using (PushLogContextProperties(area, source))
+            {
+                _output.Write((SerilogLogEventLevel)level, messageTemplate);
+            }
+        }
+
+        public void Log<T0>(
+            LogEventLevel level, 
+            string area, object source,
+            string messageTemplate, 
+            T0 propertyValue0)
+        {
+            Contract.Requires<ArgumentNullException>(area != null);
+            Contract.Requires<ArgumentNullException>(messageTemplate != null);
+
+            using (PushLogContextProperties(area, source))
+            {
+                _output.Write((SerilogLogEventLevel)level, messageTemplate, propertyValue0);
+            }
+        }
+
+        public void Log<T0, T1>(
+            LogEventLevel level, 
+            string area,
+            object source,
+            string messageTemplate,
+            T0 propertyValue0,
+            T1 propertyValue1)
+        {
+            Contract.Requires<ArgumentNullException>(area != null);
+            Contract.Requires<ArgumentNullException>(messageTemplate != null);
+
+            using (PushLogContextProperties(area, source))
+            {
+                _output.Write((SerilogLogEventLevel)level, messageTemplate, propertyValue0, propertyValue1);
+            }
+        }
+
+        public void Log<T0, T1, T2>(
+            LogEventLevel level, 
+            string area, 
+            object source, 
+            string messageTemplate, 
+            T0 propertyValue0,
+            T1 propertyValue1, 
+            T2 propertyValue2)
+        {
+            Contract.Requires<ArgumentNullException>(area != null);
+            Contract.Requires<ArgumentNullException>(messageTemplate != null);
+
+            using (PushLogContextProperties(area, source))
+            {
+                _output.Write((SerilogLogEventLevel)level, messageTemplate, propertyValue0, propertyValue1, propertyValue2);
+            }
+        }
+
         /// <inheritdoc/>
         public void Log(
             AvaloniaLogEventLevel level,
@@ -45,12 +115,40 @@ namespace Avalonia.Logging.Serilog
             Contract.Requires<ArgumentNullException>(area != null);
             Contract.Requires<ArgumentNullException>(messageTemplate != null);
 
-            using (LogContext.PushProperty("Area", area))
-            using (LogContext.PushProperty("SourceType", source?.GetType()))
-            using (LogContext.PushProperty("SourceHash", source?.GetHashCode()))
+            using (PushLogContextProperties(area, source))
             {
                 _output.Write((SerilogLogEventLevel)level, messageTemplate, propertyValues);
             }
         }
+
+        private static LogContextDisposable PushLogContextProperties(string area, object source)
+        {
+            return new LogContextDisposable(
+                LogContext.PushProperty("Area", area),
+                LogContext.PushProperty("SourceType", source?.GetType()),
+                LogContext.PushProperty("SourceHash", source?.GetHashCode())
+                );
+        }
+        
+        private readonly struct LogContextDisposable : IDisposable
+        {
+            private readonly IDisposable _areaDisposable;
+            private readonly IDisposable _sourceTypeDisposable;
+            private readonly IDisposable _sourceHashDisposable;
+
+            public LogContextDisposable(IDisposable areaDisposable, IDisposable sourceTypeDisposable, IDisposable sourceHashDisposable)
+            {
+                _areaDisposable = areaDisposable;
+                _sourceTypeDisposable = sourceTypeDisposable;
+                _sourceHashDisposable = sourceHashDisposable;
+            }
+
+            public void Dispose()
+            {
+                _areaDisposable.Dispose();
+                _sourceTypeDisposable.Dispose();
+                _sourceHashDisposable.Dispose();
+            }
+        }
     }
 }

src/Avalonia.Visuals/Visual.cs

@@ -359,7 +359,7 @@ namespace Avalonia
         /// <param name="e">The event args.</param>
         protected virtual void OnAttachedToVisualTreeCore(VisualTreeAttachmentEventArgs e)
         {
-            Logger.Verbose(LogArea.Visual, this, "Attached to visual tree");
+            Logger.Log(LogEventLevel.Verbose, LogArea.Visual, this, "Attached to visual tree");
 
             _visualRoot = e.Root;
 
@@ -388,7 +388,7 @@ namespace Avalonia
         /// <param name="e">The event args.</param>
         protected virtual void OnDetachedFromVisualTreeCore(VisualTreeAttachmentEventArgs e)
         {
-            Logger.Verbose(LogArea.Visual, this, "Detached from visual tree");
+            Logger.Log(LogEventLevel.Verbose, LogArea.Visual, this, "Detached from visual tree");
 
             _visualRoot = null;
 

tests/Avalonia.UnitTests/TestLogSink.cs

@@ -16,7 +16,7 @@ namespace Avalonia.UnitTests
 
     public class TestLogSink : ILogSink
     {
-        private LogCallback _callback;
+        private readonly LogCallback _callback;
 
         public TestLogSink(LogCallback callback)
         {
@@ -30,7 +30,35 @@ namespace Avalonia.UnitTests
             return Disposable.Create(() => Logger.Sink = null);
         }
 
-        public void Log(LogEventLevel level, string area, object source, string messageTemplate, params object[] propertyValues)
+        public bool IsEnabled(LogEventLevel level)
+        {
+            return true;
+        }
+
+        public void Log(LogEventLevel level, string area, object source, string messageTemplate)
+        {
+            _callback(level, area, source, messageTemplate);
+        }
+
+        public void Log<T0>(LogEventLevel level, string area, object source, string messageTemplate, T0 propertyValue0)
+        {
+            _callback(level, area, source, messageTemplate, propertyValue0);
+        }
+
+        public void Log<T0, T1>(LogEventLevel level, string area, object source, string messageTemplate,
+            T0 propertyValue0, T1 propertyValue1)
+        {
+            _callback(level, area, source, messageTemplate, propertyValue0, propertyValue1);
+        }
+
+        public void Log<T0, T1, T2>(LogEventLevel level, string area, object source, string messageTemplate,
+            T0 propertyValue0, T1 propertyValue1, T2 propertyValue2)
+        {
+            _callback(level, area, source, messageTemplate, propertyValue0, propertyValue1, propertyValue2);
+        }
+
+        public void Log(LogEventLevel level, string area, object source, string messageTemplate,
+            params object[] propertyValues)
         {
             _callback(level, area, source, messageTemplate, propertyValues);
         }