Update to newer version of Serilog that supports flushing (#499)

Author: pakrym

src/Microsoft.Extensions.Logging.AzureAppServices/AzureAppServicesDiagnosticsSettings.cs

@@ -41,7 +41,14 @@ public class AzureAppServicesDiagnosticsSettings
         /// </summary>
         public string BlobName { get; set; } = "applicationLog.txt";
 
+        /// <summary>
         /// Gets of sets the maximum size of the background log message queue.
+        /// </summary>
         public int BackgroundQueueSize { get; set; }
+
+        /// <summary>
+        /// Gets or sets the period after which logs will be flushed to disk.
+        /// </summary>
+        public TimeSpan? FileFlushPeriod { get; set; } = TimeSpan.FromSeconds(1);
     }
 }

src/Microsoft.Extensions.Logging.AzureAppServices/Internal/AzureAppServicesDiagnosticsLoggerProvider.cs

@@ -38,7 +38,8 @@ public AzureAppServicesDiagnosticsLoggerProvider(WebAppContext context, AzureApp
                     settings.FileSizeLimit,
                     settings.RetainedFileCountLimit,
                     settings.BackgroundQueueSize,
-                    settings.OutputTemplate);
+                    settings.OutputTemplate,
+                    settings.FileFlushPeriod);
 
                 _loggerFactory.AddSerilog(fileLoggerProvider.ConfigureLogger(_configurationReader));
                 if (!string.IsNullOrEmpty(config.BlobContainerUrl))

src/Microsoft.Extensions.Logging.AzureAppServices/Internal/FileLoggerProvider.cs

@@ -6,6 +6,7 @@
 using Serilog;
 using Serilog.Core;
 using Serilog.Formatting.Display;
+using Serilog.Sinks.File;
 using Serilog.Sinks.RollingFile;
 
 namespace Microsoft.Extensions.Logging.AzureAppServices.Internal
@@ -19,6 +20,7 @@ public class FileLoggerProvider
         private readonly int _retainedFileCountLimit;
         private readonly int _backgroundQueueSize;
         private readonly string _outputTemplate;
+        private readonly TimeSpan? _flushPeriod;
 
         private const string FileNamePattern = "diagnostics-{Date}.txt";
 
@@ -29,7 +31,8 @@ public class FileLoggerProvider
         /// <param name="retainedFileCountLimit">A strictly positive value representing the maximum retained file count</param>
         /// <param name="backgroundQueueSize">The maximum size of the background queue</param>
         /// <param name="outputTemplate">A message template describing the output messages</param>
-        public FileLoggerProvider(int fileSizeLimit, int retainedFileCountLimit, int backgroundQueueSize, string outputTemplate)
+        /// <param name="flushPeriod">A period after which logs will be flushed to disk</param>
+        public FileLoggerProvider(int fileSizeLimit, int retainedFileCountLimit, int backgroundQueueSize, string outputTemplate, TimeSpan? flushPeriod)
         {
             if (outputTemplate == null)
             {
@@ -48,6 +51,7 @@ public FileLoggerProvider(int fileSizeLimit, int retainedFileCountLimit, int bac
             _retainedFileCountLimit = retainedFileCountLimit;
             _backgroundQueueSize = backgroundQueueSize;
             _outputTemplate = outputTemplate;
+            _flushPeriod = flushPeriod;
         }
 
         /// <inheritdoc />
@@ -69,7 +73,17 @@ public Logger ConfigureLogger(IWebAppLogConfigurationReader reader)
 
             var messageFormatter = new MessageTemplateTextFormatter(_outputTemplate, null);
             var rollingFileSink = new RollingFileSink(logsFilePattern, messageFormatter, _fileSizeLimit, _retainedFileCountLimit);
-            var backgroundSink = new BackgroundSink(rollingFileSink, _backgroundQueueSize);
+
+            ILogEventSink flushingSink;
+            if (_flushPeriod != null)
+            {
+                flushingSink = new PeriodicFlushToDiskSink(rollingFileSink, _flushPeriod.Value);
+            }
+            else
+            {
+                flushingSink = rollingFileSink;
+            }
+            var backgroundSink = new BackgroundSink(flushingSink, _backgroundQueueSize);
 
             var loggerConfiguration = new LoggerConfiguration();
             loggerConfiguration.WriteTo.Sink(backgroundSink);

src/Microsoft.Extensions.Logging.AzureAppServices/project.json

@@ -19,7 +19,7 @@
     "NETStandard.Library": "1.6.1-*",
     "Serilog.Extensions.Logging": "1.0.0",
     "Serilog.Sinks.PeriodicBatching": "2.0.0",
-    "Serilog.Sinks.RollingFile": "2.1.0",
+    "Serilog.Sinks.RollingFile": "3.1.0",
     "WindowsAzure.Storage": "7.2.0"
   },
   "frameworks": {