LogFile has different implementations for Windows using Win32 API and STD for other platforms where Poco::FileOutputStream is used. Poco::FileOutputStream has Windows and Posix implementations.

LogFile calls FlushFileBuffers on Windows which forcefully flushes buffers to disk. Posix equivalent would be fsync.

• New function fsync (or flushToDisk) shall be added to FileStream_POSIX and FileStream_WIN32.
• Implementation of LogFile shall be unified to use FileOutputStream

Related: #2443, #4429.