Existing Facebook code sets WriteBufferManager's buffersize parameters once at database start up. The system might need to lower that value as column families and/or .sst files begin to chew up RAM. The start up value comes from db_write_buffer_size.
This modification allows an informed user to pass an application created WriteBufferManager within DBOptions and subsequently change its internal buffersize as needed.
Existing Facebook code sets WriteBufferManager's buffersize parameters once at database start up. The system might need to lower that value as column families and/or .sst files begin to chew up RAM. The start up value comes from db_write_buffer_size.
This modification allows an informed user to pass an application created WriteBufferManager within DBOptions and subsequently change its internal buffersize as needed.