FastBuffer::resize will not resize below 200

[Karsten1987]

Connects to ros2/demos#185

I wonder why the implementation of FastBuffer::resize can't resize an empty buffer below 200.
https://github.com/eProsima/Fast-CDR/blob/master/src/cpp/FastBuffer.cpp#L45-L81

If I have an empty buffer and want to resize it to an exact number of size - let's say I know how much data I want to copy into it - the minimum size of it is BUFFER_START_LENGTH, which is hard set to 200
https://github.com/eProsima/Fast-CDR/blob/master/src/cpp/FastBuffer.cpp#L23

why is that?

[richiware]

FastBuffer class can handle a user's buffer (char*) or an internal buffer. Usually I use the first approach. I know the length of my serialized data and I give a buffer to FastBuffer.

The second approach was useful if user doesn't know the length of the serialized data and doesn't want to precaculate it. We select to start with 200bytes. Cdr starts serializing and when the internal buffer size is insufficient, it will reallocate more and continue serializing.

[Karsten1987]

I understand. However, this requires that the memory for the buffer is managed externally. That is to alloc and de-allocate the external buffer.
With the referenced reserve function, the buffer could stay internally and the destructor of the class can conveniently cleanup the allocated memory.

[Karsten1987]

closed by e986a9e