NLog.Targets.FileTarget.TryArchiveFile C# (CSharp) Method

        private void TryArchiveFile(string fileName, LogEventInfo ev, int upcomingWriteSize)
        {
            string archiveFile = string.Empty;

            try
            {
#if !SILVERLIGHT && !__IOS__ && !__ANDROID__
                this.fileAppenderCache.InvalidateAppendersForInvalidFiles();
#endif
                archiveFile = this.GetArchiveFileName(fileName, ev, upcomingWriteSize);
                if (!string.IsNullOrEmpty(archiveFile))
                {
                    // Close possible stale file handles, before doing extra check
                    if (archiveFile != fileName)
                        this.fileAppenderCache.InvalidateAppender(fileName);
                    this.fileAppenderCache.InvalidateAppender(archiveFile);
                }
            }
            catch (Exception exception)
            {
                InternalLogger.Warn(exception, "Failed to check archive for file '{0}'.", fileName);
                if (exception.MustBeRethrown())
                {
                    throw;
                }
            }

            if (!string.IsNullOrEmpty(archiveFile))
            {
#if SupportsMutex
                Mutex archiveMutex = this.fileAppenderCache.GetArchiveMutex(fileName);
                try
                {
                    if (archiveMutex != null)
                        archiveMutex.WaitOne();
                }
                catch (AbandonedMutexException)
                {
                    // ignore the exception, another process was killed without properly releasing the mutex
                    // the mutex has been acquired, so proceed to writing
                    // See: http://msdn.microsoft.com/en-us/library/system.threading.abandonedmutexexception.aspx
                }
#endif
                try
                {
                    // Check again if archive is needed. We could have been raced by another process
                    var validatedArchiveFile = this.GetArchiveFileName(fileName, ev, upcomingWriteSize);
                    if (string.IsNullOrEmpty(validatedArchiveFile))
                    {
                        if (archiveFile != fileName)
                            this.initializedFiles.Remove(fileName);
                        this.initializedFiles.Remove(archiveFile);
                        return;
                    }

                    archiveFile = validatedArchiveFile;
                    this.DoAutoArchive(archiveFile, ev);
                }
                catch (Exception exception)
                {
                    InternalLogger.Warn(exception, "Failed to archive file '{0}'.", archiveFile);
                    if (exception.MustBeRethrown())
                    {
                        throw;
                    }
                }
                finally
                {
#if SupportsMutex
                    if (archiveMutex != null)
                        archiveMutex.ReleaseMutex();
#endif
                }
            }
        }