[BC] FileLoggerProcessor.LogFileInfo: encapsulation revised (setters …

…of AppendStream, EnsurePreambleAsync hidden)

+ minor optimization for LogFileAccessMode.OpenTemporarily

source/FileLogger/FileLoggerProcessor.cs

@@ -56,13 +56,23 @@ protected class LogFileInfo
 
  public int Counter { get; set; }
  public string CurrentPath { get; set; }
- public Func<LogFileInfo, CancellationToken, ValueTask> EnsurePreambleAsync { get; set; }
- public Stream AppendStream { get; set; }
+
+ public Stream AppendStream { get; private set; }
+ public Func<LogFileInfo, CancellationToken, ValueTask> EnsurePreambleAsync { get; private set; }
 
  public void OpenAppendStream(IFileInfo fileInfo)
  {
  AppendStream = FileAppender.CreateAppendStream(fileInfo);
- EnsurePreambleAsync = FileLoggerProcessor.EnsurePreambleAsync;
+
+ // the compiler creates a cached delegate for non-capturing lambda expressions,
+ // so frequent allocation in the case of LogFileAccessMode.OpenTemporarily can be avoided this way
+ EnsurePreambleAsync = async (logFile, cancellationToken) =>
+ {
+ if (logFile.AppendStream.Length == 0)
+ await WriteBytesAsync(logFile, logFile.Encoding.GetPreamble(), cancellationToken).ConfigureAwait(false);
+
+ logFile.EnsurePreambleAsync = (lf, ct) => default;
+ };
  }
 
  public void CloseAppendStream()
@@ -325,23 +335,11 @@ protected virtual bool UpdateFilePath(LogFileInfo logFile, FileLogEntry entry, C
  return true;
  }
 
- private static async ValueTask EnsurePreambleAsync(LogFileInfo logFile, CancellationToken cancellationToken)
- {
- if (logFile.AppendStream.Length == 0)
- {
- var preamble = logFile.Encoding.GetPreamble();
- await WriteBytesAsync(logFile, preamble, cancellationToken).ConfigureAwait(false);
- }
-
- logFile.EnsurePreambleAsync = (lf, ct) => default;
- }
-
  protected virtual async ValueTask WriteEntryCoreAsync(LogFileInfo logFile, FileLogEntry entry, CancellationToken cancellationToken)
  {
  await logFile.EnsurePreambleAsync(logFile, cancellationToken).ConfigureAwait(false);
 
- var data = logFile.Encoding.GetBytes(entry.Text);
- await WriteBytesAsync(logFile, data, cancellationToken).ConfigureAwait(false);
+ await WriteBytesAsync(logFile, logFile.Encoding.GetBytes(entry.Text), cancellationToken).ConfigureAwait(false);
  }
 
  private async ValueTask WriteEntryAsync(LogFileInfo logFile, FileLogEntry entry, CancellationToken cancellationToken)