add option to reduce dump flush buffer size to 1

src/lib/utils/rotatefile.cpp

@@ -82,7 +82,7 @@ void RotateFile::write(const unsigned char* value, const size_t size, const bool
     fwrite(value, (streamsize)size, 1, m_stream);
     m_fileSize += size;
     m_flushSize += size;
-    if (m_flushSize > 16) {
+    if (m_flushSize >= m_flushBuffer) {
       fflush(m_stream);
       m_flushSize = 0;
     }

src/lib/utils/rotatefile.h

@@ -43,10 +43,11 @@ class RotateFile {
    * @param fileName the name of the file write to.
    * @param maxSize the maximum size of the file to write to.
    * @param textMode whether to write each byte with prefixed timestamp and direction as text.
+   * @param flushBuffer the size of the flush buffer.
    */
-  RotateFile(const string fileName, const unsigned int maxSize, const bool textMode = false)
+  RotateFile(const string fileName, const unsigned int maxSize, const bool textMode = false, const unsigned int flushBuffer = 16)
     : m_enabled(false), m_fileName(fileName), m_maxSize(maxSize), m_textMode(textMode), m_stream(), m_fileSize(0),
-      m_flushSize(0) {}
+      m_flushSize(0), m_flushBuffer(flushBuffer) {}
 
   /**
    * Destructor.
@@ -98,6 +99,9 @@ class RotateFile {
 
   /** the number of bytes written to @a m_file since the last flush. */
   uint64_t m_flushSize;
+
+  /** the size of the flush buffer. */
+  const unsigned int m_flushBuffer;
 };
 
 }  // namespace ebusd