User-configurable synchronized writes

Build.ps1

@@ -1,9 +1,9 @@
-echo "build: Build started"
+Write-Host "build: Build started"
 
 Push-Location $PSScriptRoot
 
 if(Test-Path .\artifacts) {
-	echo "build: Cleaning .\artifacts"
+    Write-Host "build: Cleaning .\artifacts"
 	Remove-Item .\artifacts -Force -Recurse
 }
 
@@ -15,13 +15,13 @@ $suffix = @{ $true = ""; $false = "$($branch.Substring(0, [math]::Min(10,$branch
 $commitHash = $(git rev-parse --short HEAD)
 $buildSuffix = @{ $true = "$($suffix)-$($commitHash)"; $false = "$($branch)-$($commitHash)" }[$suffix -ne ""]
 
-echo "build: Package version suffix is $suffix"
-echo "build: Build version suffix is $buildSuffix" 
+Write-Host "build: Package version suffix is $suffix"
+Write-Host "build: Build version suffix is $buildSuffix" 
 
-foreach ($src in ls src/*) {
+foreach ($src in Get-ChildItem src/*) {
     Push-Location $src
 
-	echo "build: Packaging project in $src"
+    Write-Host "build: Packaging project in $src"
 
     & dotnet build -c Release --version-suffix=$buildSuffix
     if ($suffix) {
@@ -34,10 +34,21 @@ foreach ($src in ls src/*) {
     Pop-Location
 }
 
+foreach ($sample in Get-ChildItem sample/*) {
+    Push-Location $sample
+
+    Write-Host "build: Testing project in $sample"
+
+    & dotnet build -c Release --version-suffix=$buildSuffix
+    if($LASTEXITCODE -ne 0) { exit 3 }
+
+    Pop-Location
+}
+
 foreach ($test in ls test/*.Tests) {
     Push-Location $test
 
-	echo "build: Testing project in $test"
+	Write-Host "build: Testing project in $test"
 
     & dotnet test -c Release
     if($LASTEXITCODE -ne 0) { exit 3 }

sample/SyncWritesDemo/Program.cs

@@ -0,0 +1,57 @@
+using Serilog;
+using Serilog.Sinks.SystemConsole.Themes;
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace SyncWritesDemo
+{
+    public static class Program
+    {
+        public static void Main(string[] args)
+        {
+            Console.WriteLine("A sample of how to sync writes to the console sink.");
+
+            if (args != null && args.Length == 1)
+            {
+                switch (args[0])
+                {
+                    case "--sync-root-default":
+                        SystemConsoleSyncTest(syncRootForLogger1: null, syncRootForLogger2: null);
+                        return;
+                    case "--sync-root-separate":
+                        SystemConsoleSyncTest(syncRootForLogger1: new object(), syncRootForLogger2: new object());
+                        return;
+                    case "--sync-root-same":
+                        var sameSyncRoot = new object();
+                        SystemConsoleSyncTest(syncRootForLogger1: sameSyncRoot, syncRootForLogger2: sameSyncRoot);
+                        return;
+                }
+            }
+
+            Console.WriteLine("Expecting one of the following arguments:{0}--sync-root-default{0}--sync-root-separate{0}--sync-root-same", Environment.NewLine);
+        }
+
+        static void SystemConsoleSyncTest(object syncRootForLogger1, object syncRootForLogger2)
+        {
+            var logger1 = new LoggerConfiguration()
+                .MinimumLevel.Verbose()
+                .Enrich.WithProperty("Logger", "logger1")
+                .WriteTo.Console(theme: SystemConsoleTheme.Literate, syncRoot: syncRootForLogger1)
+                .CreateLogger();
+
+            var logger2 = new LoggerConfiguration()
+                .MinimumLevel.Verbose()
+                .Enrich.WithProperty("Logger", "logger2")
+                .WriteTo.Console(theme: SystemConsoleTheme.Literate, syncRoot: syncRootForLogger2)
+                .CreateLogger();
+
+            var options = new ParallelOptions { MaxDegreeOfParallelism = 8 };
+            System.Threading.Tasks.Parallel.For(0, 1000, options, (i, loopState) =>
+            {
+                var logger = (i % 2 == 0) ? logger1 : logger2;
+                logger.Information("Event {Iteration} generated by {ThreadId}", i, Thread.CurrentThread.ManagedThreadId);
+            });
+        }
+    }
+}

sample/SyncWritesDemo/SyncWritesDemo.csproj

@@ -0,0 +1,12 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>netcoreapp2.0</TargetFramework>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\..\src\Serilog.Sinks.Console\Serilog.Sinks.Console.csproj" />
+  </ItemGroup>
+
+</Project>

serilog-sinks-console.sln

@@ -27,6 +27,8 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "sample", "sample", "{CF8176
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "ConsoleDemo", "sample\ConsoleDemo\ConsoleDemo.csproj", "{DBF4907A-63A2-4895-8DEF-59F90C20380B}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "SyncWritesDemo", "sample\SyncWritesDemo\SyncWritesDemo.csproj", "{633AE0AD-C9D4-440D-874A-C0F4632DB75F}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -45,6 +47,10 @@ Global
 		{DBF4907A-63A2-4895-8DEF-59F90C20380B}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{DBF4907A-63A2-4895-8DEF-59F90C20380B}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{DBF4907A-63A2-4895-8DEF-59F90C20380B}.Release|Any CPU.Build.0 = Release|Any CPU
+		{633AE0AD-C9D4-440D-874A-C0F4632DB75F}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{633AE0AD-C9D4-440D-874A-C0F4632DB75F}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{633AE0AD-C9D4-440D-874A-C0F4632DB75F}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{633AE0AD-C9D4-440D-874A-C0F4632DB75F}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -53,6 +59,7 @@ Global
 		{866A028E-27DB-49A0-AC78-E5FEF247C099} = {037440DE-440B-4129-9F7A-09B42D00397E}
 		{1D56534C-4009-42C2-A573-789CAE6B8AA9} = {7D0692CD-F95D-4BF9-8C63-B4A1C078DF23}
 		{DBF4907A-63A2-4895-8DEF-59F90C20380B} = {CF817664-4CEC-4B6A-9C57-A0D687757D82}
+		{633AE0AD-C9D4-440D-874A-C0F4632DB75F} = {CF817664-4CEC-4B6A-9C57-A0D687757D82}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution
 		SolutionGuid = {43C32ED4-D39A-4E27-AE99-7BB8C883833C}

src/Serilog.Sinks.Console/ConsoleLoggerConfigurationExtensions.cs

@@ -28,6 +28,7 @@ namespace Serilog
     /// </summary>
     public static class ConsoleLoggerConfigurationExtensions
     {
+        static object DefaultSyncRoot = new object();
         const string DefaultConsoleOutputTemplate = "[{Timestamp:HH:mm:ss} {Level:u3}] {Message:lj}{NewLine}{Exception}";
 
         /// <summary>
@@ -38,6 +39,9 @@ public static class ConsoleLoggerConfigurationExtensions
         /// events passed through the sink. Ignored when <paramref name="levelSwitch"/> is specified.</param>
         /// <param name="outputTemplate">A message template describing the format used to write to the sink.
         /// The default is <code>"[{Timestamp:HH:mm:ss} {Level:u3}] {Message:lj}{NewLine}{Exception}"</code>.</param>
+        /// <param name="syncRoot">An object that will be used to `lock` (sync) access to the console output. If you specify this, you
+        /// will have the ability to lock on this object, and guarantee that the console sink will not be about to output anything while
+        /// the lock is held.</param>
         /// <param name="formatProvider">Supplies culture-specific formatting information, or null.</param>
         /// <param name="levelSwitch">A switch allowing the pass-through minimum level
         /// to be changed at runtime.</param>
@@ -52,7 +56,8 @@ public static LoggerConfiguration Console(
             IFormatProvider formatProvider = null,
             LoggingLevelSwitch levelSwitch = null,
             LogEventLevel? standardErrorFromLevel = null,
-            ConsoleTheme theme = null)
+            ConsoleTheme theme = null,
+            object syncRoot = null)
         {
             if (sinkConfiguration == null) throw new ArgumentNullException(nameof(sinkConfiguration));
             if (outputTemplate == null) throw new ArgumentNullException(nameof(outputTemplate));
@@ -61,8 +66,10 @@ public static LoggerConfiguration Console(
                 ConsoleTheme.None :
                 theme ?? SystemConsoleThemes.Literate;
 
+            syncRoot = syncRoot ?? DefaultSyncRoot;
+
             var formatter = new OutputTemplateRenderer(appliedTheme, outputTemplate, formatProvider);
-            return sinkConfiguration.Sink(new ConsoleSink(appliedTheme, formatter, standardErrorFromLevel), restrictedToMinimumLevel, levelSwitch);
+            return sinkConfiguration.Sink(new ConsoleSink(appliedTheme, formatter, standardErrorFromLevel, syncRoot), restrictedToMinimumLevel, levelSwitch);
         }
 
         /// <summary>
@@ -71,6 +78,9 @@ public static LoggerConfiguration Console(
         /// <param name="sinkConfiguration">Logger sink configuration.</param>
         /// <param name="formatter">Controls the rendering of log events into text, for example to log JSON. To
         /// control plain text formatting, use the overload that accepts an output template.</param>
+        /// <param name="syncRoot">An object that will be used to `lock` (sync) access to the console output. If you specify this, you
+        /// will have the ability to lock on this object, and guarantee that the console sink will not be about to output anything while
+        /// the lock is held.</param>
         /// <param name="restrictedToMinimumLevel">The minimum level for
         /// events passed through the sink. Ignored when <paramref name="levelSwitch"/> is specified.</param>
         /// <param name="levelSwitch">A switch allowing the pass-through minimum level
@@ -82,12 +92,14 @@ public static LoggerConfiguration Console(
             ITextFormatter formatter,
             LogEventLevel restrictedToMinimumLevel = LevelAlias.Minimum,
             LoggingLevelSwitch levelSwitch = null,
-            LogEventLevel? standardErrorFromLevel = null)
+            LogEventLevel? standardErrorFromLevel = null,
+            object syncRoot = null)
         {
             if (sinkConfiguration == null) throw new ArgumentNullException(nameof(sinkConfiguration));
             if (formatter == null) throw new ArgumentNullException(nameof(formatter));
 
-            return sinkConfiguration.Sink(new ConsoleSink(ConsoleTheme.None, formatter, standardErrorFromLevel), restrictedToMinimumLevel, levelSwitch);
+            syncRoot = syncRoot ?? DefaultSyncRoot;
+            return sinkConfiguration.Sink(new ConsoleSink(ConsoleTheme.None, formatter, standardErrorFromLevel, syncRoot), restrictedToMinimumLevel, levelSwitch);
         }
     }
 }

src/Serilog.Sinks.Console/Sinks/SystemConsole/ConsoleSink.cs

@@ -28,7 +28,7 @@ class ConsoleSink : ILogEventSink
         readonly LogEventLevel? _standardErrorFromLevel;
         readonly ConsoleTheme _theme;
         readonly ITextFormatter _formatter;
-        readonly object _syncRoot = new object();
+        readonly object _syncRoot;
 
         const int DefaultWriteBufferCapacity = 256;
 
@@ -40,11 +40,13 @@ static ConsoleSink()
         public ConsoleSink(
             ConsoleTheme theme,
             ITextFormatter formatter,
-            LogEventLevel? standardErrorFromLevel)
+            LogEventLevel? standardErrorFromLevel,
+            object syncRoot)
         {
             _standardErrorFromLevel = standardErrorFromLevel;
             _theme = theme ?? throw new ArgumentNullException(nameof(theme));
             _formatter = formatter;
+            _syncRoot = syncRoot ?? throw new ArgumentNullException(nameof(syncRoot));
         }
 
         public void Emit(LogEvent logEvent)