Added some reentry checks to try and prevent overlapping io calls.

Author: niemyjski

src/Exceptionless/Logging/FileExceptionlessLog.cs

@@ -1,4 +1,4 @@
-#if !PORTABLE && !NETSTANDARD1_2
+#if !PORTABLE && !NETSTANDARD1_2
 using System;
 using System.Collections.Concurrent;
 using System.IO;
@@ -13,6 +13,7 @@ public class FileExceptionlessLog : IExceptionlessLog, IDisposable {
         private readonly bool _append;
         private bool _firstWrite = true;
         private bool _isFlushing = false;
+        private bool _isCheckingFileSize = false;
 
         public FileExceptionlessLog(string filePath, bool append = false) {
             if (String.IsNullOrEmpty(filePath))
@@ -66,7 +67,7 @@ protected internal virtual long GetFileSize() {
             try {
                 if (File.Exists(FilePath))
                     return new FileInfo(FilePath).Length;
-            } catch (IOException ex) {
+            } catch (Exception ex) {
                 System.Diagnostics.Trace.WriteLine("Exceptionless: Error getting size of file: {0}", ex.Message);
             }
 
@@ -119,9 +120,12 @@ public void Flush() {
             if (_isFlushing || _buffer.Count == 0)
                 return;
 
-            if (DateTime.Now.Subtract(_lastSizeCheck).TotalSeconds > 120)
+            if (DateTime.UtcNow.Subtract(_lastSizeCheck).TotalSeconds > 120)
                 CheckFileSize();
 
+            if (_isFlushing)
+                return;
+            
             try {
                 _isFlushing = true;
 
@@ -189,14 +193,20 @@ private void WriteEntry(LogLevel level, string entry) {
             _buffer.Enqueue(new LogEntry(level, entry));
         }
 
-        private DateTime _lastSizeCheck = DateTime.Now;
+        private DateTime _lastSizeCheck = DateTime.UtcNow;
         protected const long FIVE_MB = 5 * 1024 * 1024;
 
         internal void CheckFileSize() {
-            _lastSizeCheck = DateTime.Now;
+            if (_isCheckingFileSize)
+                return;
 
-            if (GetFileSize() <= FIVE_MB)
+            _isCheckingFileSize = true;
+            _lastSizeCheck = DateTime.UtcNow;
+
+            if (GetFileSize() <= FIVE_MB) {
+                _isCheckingFileSize = false;
                 return;
+            }
 
             // get the last X lines from the current file
             string lastLines = String.Empty;
@@ -212,8 +222,10 @@ internal void CheckFileSize() {
                 System.Diagnostics.Trace.WriteLine("Exceptionless: Error getting last X lines from the log file: {0}", ex.Message);
             }
 
-            if (String.IsNullOrEmpty(lastLines))
+            if (String.IsNullOrEmpty(lastLines)) {
+                _isCheckingFileSize = false;
                 return;
+            }
 
             // overwrite the log file and initialize it with the last X lines it had
             try {
@@ -226,6 +238,8 @@ internal void CheckFileSize() {
             } catch (Exception ex) {
                 System.Diagnostics.Trace.WriteLine("Exceptionless: Error rewriting the log file after trimming it: {0}", ex.Message);
             }
+            
+            _isCheckingFileSize = false;
         }
 
         private void OnFlushTimer(object state) {