Random_Access_Reader Class Reference

#include <Random_Access_Reader.h>

Public Member Functions
std::string	get_line (int local_line_nr)
void	setup (const std::string &filename, std::streampos spos)
	Random_Access_Reader (const std::string &filename, std::streampos spos)

Public Attributes
std::ifstream	ifs
	input stream: only closed on destruction:
std::streampos	startpos
	position in stream corresponding to starting point for the present thread
int	lastline
	Number of last processed line; check if we have to seek position or not.
std::string	lastline_string
	String value of last line; good for reading IA files.

Protected Attributes
bool	was_setup

Detailed Description

Reader that will we used for diagonalizing sparse matrices from files.

Solves the problem: Sparse_Matrix_Generator requires a function that allows random access to the rows of a sparse matrix. However, a naive implementation would stress the file system, because the files have to be read many times and always from the beginning.

Idea: Assume that one typically goes through the files sequentially, i.e. line by line, and make the access efficient in this case. -> Keep stream open and keep track of which line was the last in the stream.

Also: Distribute between threads -> First step: communicate position in stream where data for each thread starts. For CSR sparse matrices, we need to open 3 different files. So, let initial distribution of stream line positions handled somewhere else.

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The documentation for this class was generated from the following files:

• /home/moritz/QNANO_PRODUCTION/qnano_new/include/tools/Random_Access_Reader.h
• /home/moritz/QNANO_PRODUCTION/qnano_new/sources/tools/Random_Access_Reader.cc