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POWhy ReadDirectoryChangesW, with only FILE_NOTIFY_CHANGE_LAST_WRITE filter, does signal more than one event on file editing?
 

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  1. POWhy ReadDirectoryChangesW, with only FILE_NOTIFY_CHANGE_LAST_WRITE filter, does signal more than one event on file editing?
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    <p>I am monitoring in separate thread application configuration file, which in some cases may be INI in another XML or another. Code of thread monitoring directory (in Delphi) is something like this:</p> <pre><code>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 &lt;&gt; 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; </code></pre> <p>Why it signals at least 2 times and how to get correct signal when some flag in config file was changed and was saved?</p>
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      1. POWhy ReadDirectoryChangesW, with only FILE_NOTIFY_CHANGE_LAST_WRITE filter, does signal more than one event on file editing?
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      1. POWhy ReadDirectoryChangesW, with only FILE_NOTIFY_CHANGE_LAST_WRITE filter, does signal more than one event on file editing?
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      1. POWhy ReadDirectoryChangesW, with only FILE_NOTIFY_CHANGE_LAST_WRITE filter, does signal more than one event on file editing?
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    1. COBy the way: the FILE_NOTIFY_CHANGE_LAST_ACCESS only filter is signaling only once - WHAT is the difference?
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      1. POWhy ReadDirectoryChangesW, with only FILE_NOTIFY_CHANGE_LAST_WRITE filter, does signal more than one event on file editing?
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