爲什麼只有FILE_NOTIFY_CHANGE_LAST_WRITE過濾器的ReadDirectoryChangesW會在文件編輯時發出多個事件信號？

Question

我正在監視單獨的線程應用程序配置文件，在某些情況下，這可能是另一個XML或另一個XML中的INI。 （在Delphi）線程監控目錄的 代碼是這樣的：

procedure TWatcherThread.Execute; 
type 
    PFileNotifyInformation = ^TFileNotifyInformation; 
    TFileNotifyInformation = record 
    NextEntryOffset: DWORD; 
    Action: DWORD; 
    FileNameLength: DWORD; 
    FileName: WideChar; 
    end; 
const 
    BufferLength = 65536; 
var 
    Filter, BytesRead: DWORD; 
    InfoPointer: PFileNotifyInformation; 
    Offset, NextOffset: DWORD; 
    Buffer: array[0..BufferLength - 1] of byte; 
    Overlap: TOverlapped; 
    Events: array[0..1] of THandle; 
    WaitResult: DWORD; 
    FileName, s: string; 
begin 
    if fDirHandle <> INVALID_HANDLE_VALUE then begin 
    Filter := FILE_NOTIFY_CHANGE_LAST_WRITE; 

    FillChar(Overlap, SizeOf(TOverlapped), 0); 
    Overlap.hEvent := fChangeHandle; 

    Events[0] := fChangeHandle; 
    Events[1] := fShutdownHandle; 

    while not Terminated do begin 
     FillChar(Buffer,SizeOf(Buffer),0); 
     if ReadDirectoryChangesW (fDirHandle, @Buffer[0], BufferLength, TRUE, 
     Filter, @BytesRead, @Overlap, nil) 
     then begin 
     WaitResult := WaitForMultipleObjects(2, @Events[0], FALSE, INFINITE); 
     if WaitResult = WAIT_OBJECT_0 then begin 
      InfoPointer := @Buffer[0]; 
      Offset := 0; 
      repeat 
      NextOffset := InfoPointer.NextEntryOffset; 
      FileName := WideCharToString(@InfoPointer.FileName); 

      if (InfoPointer.Action = FILE_ACTION_MODIFIED) and (CompareText(FileName, 'MyConfig.ini') = 0) then begin //read changes in config or INI file 
       // Do Action.. refresh runtime flags 
      end; 
      PByte(InfoPointer) := PByte(DWORD(InfoPointer) + NextOffset); 
      Offset := Offset + NextOffset; 
      until NextOffset = 0; 
     end; 
     end; 
    end; 
    end; 
end; 

爲什麼它的信號的至少2倍，以及如何當配置文件中的一些標誌改爲得到正確的信號，並保存？

Answer 1

雷蒙德陳解釋說這很好地在他的博客：http://blogs.msdn.com/b/oldnewthing/archive/2014/05/07/10523172.aspx

簡稱「因爲多事情進行了修改。」