Merge pull request #17 from serilog/dev

3.0.1 Release

Author: nblumhardt

README.md

@@ -14,7 +14,7 @@ To avoid bringing down apps with runaway disk usage the file sink **limits file
     .WriteTo.File("log.txt", fileSizeLimitBytes: null)
 ```
 
-> **Important:** Only one process may write to a log file at a given time. For multi-process scenarios, either use separate files or one of the non-file-based sinks.
+> **Important:** By default only one process may use a log file at a given time. See _Shared log files_ below if multi-process logging is required. 
 
 ### `<appSettings>` configuration
 
@@ -36,6 +36,14 @@ To emit JSON, rather than plain text, a formatter can be specified:
 
 To configure an alternative formatter in XML `<appSettings>`, specify the formatter's assembly-qualified type name as the setting `value`.
 
+### Shared log files
+
+Multiple processes can concurrently write to the same log file if the `shared` parameter is set to `true`:
+
+```csharp
+    .WriteTo.File("log.txt", shared: true)
+```
+
 ### Performance
 
 By default, the file sink will flush each event written through it to disk. To improve write performance, specifying `buffered: true` will permit the underlying stream to buffer writes.

src/Serilog.Sinks.File/FileLoggerConfigurationExtensions.cs

@@ -178,12 +178,12 @@ static LoggerConfiguration ConfigureFile(
 
             if (shared)
             {
-#if !ATOMIC_APPEND
-                throw new NotSupportedException("File sharing is not supported on this platform.");
-#endif
-
+#if ATOMIC_APPEND
                 if (buffered)
                     throw new ArgumentException("Buffered writes are not available when file sharing is enabled.", nameof(buffered));
+#else
+                throw new NotSupportedException("File sharing is not supported on this platform.");
+#endif
             }
 
             ILogEventSink sink;
@@ -215,4 +215,4 @@ static LoggerConfiguration ConfigureFile(
             return addSink(sink, restrictedToMinimumLevel, levelSwitch);
         }
     }  
-}
+}

src/Serilog.Sinks.File/Sinks/File/FileSink.cs

@@ -14,9 +14,6 @@
 
 using System;
 using System.IO;
-#if ATOMIC_APPEND
-using System.Security.AccessControl;
-#endif
 using System.Text;
 using Serilog.Core;
 using Serilog.Events;
@@ -64,13 +61,7 @@ public FileSink(string path, ITextFormatter textFormatter, long? fileSizeLimitBy
                 Directory.CreateDirectory(directory);
             }
 
-#if ATOMIC_APPEND
-            // FileSystemRights.AppendData improves performance substantially (~30%) when available.
-            Stream file = new FileStream(path, FileMode.Append, FileSystemRights.AppendData, FileShare.Read, 4096, FileOptions.None);
-#else
             Stream file = System.IO.File.Open(path, FileMode.Append, FileAccess.Write, FileShare.Read);
-#endif
-
             if (_fileSizeLimitBytes != null)
             {
                 file = _countingStreamWrapper = new WriteCountingStream(file);

src/Serilog.Sinks.File/Sinks/File/SharedFileSink.cs

@@ -75,7 +75,7 @@ public SharedFileSink(string path, ITextFormatter textFormatter, long? fileSizeL
                 path, 
                 FileMode.Append,
                 FileSystemRights.AppendData,
-                FileShare.Write,
+                FileShare.ReadWrite,
                 _fileStreamBufferLength,
                 FileOptions.None);
 
@@ -118,7 +118,7 @@ public void Emit(LogEvent logEvent)
                             _path,
                             FileMode.Append,
                             FileSystemRights.AppendData,
-                            FileShare.Write,
+                            FileShare.ReadWrite,
                             length,
                             FileOptions.None);
                         _fileStreamBufferLength = length;

src/Serilog.Sinks.File/project.json

@@ -1,5 +1,5 @@
 {
-  "version": "3.0.0-*",
+  "version": "3.0.1-*",
   "description": "Write Serilog events to a text file in plain or JSON format.",
   "authors": [ "Serilog Contributors" ],
   "packOptions": {