sample TPIE filestream test

README.md

Creating a simple file I/O app using TPIE

importing tpie/tpie.h and initializing tpie subsystems for

memory and streams are required

set desired memory limit

populate data using write_stream

use the TPIE interfaces to copy one tpie stream to another

test copy by reading copied file

tear down tpie subsystems with finish

read_stream.cpp

/* core tpie configurations and initializations */
#include <tpie/tpie.h>
#include <tpie/file_stream.h>
#include <string>

using std::cerr;
using std::endl;


/* a basic struct storing a 3D segment */
struct segment_t {
	double x1, y1, x2, y2;
	float z1, z2;
};

/* make a dummy segment with given x1,y1, but 
 * setting other coordinates to 0 */
struct segment_t make_segment(double x1, double y1){
	struct segment_t s;
	s.x1=x1; s.y1=y1;
	s.x2=s.y2=s.z1=s.z2=0.f;
	return s;
}

/* print x1, y1 coords of segment */
void print_item(const struct segment_t& item){
	printf("(%6.2f %6.2f)", item.x1, item.y1);
}

/* write n segment items to tpie::file_stream with given
 * output file name fname. Overwrites any previous file */
void writestream(const std::string& fname, size_t n){

	tpie::file_stream<struct segment_t> out;
	out.open(fname, tpie::open::write_only);
	for(size_t i=0; i<n; i++){
		struct segment_t item = make_segment(i, i*2.);
		print_item(item); printf("\n");
		out.write(item);
	}
}

/* Read all segments from a tpie::file_stream with
 * file name given by fname and prints results */
void readstream(const std::string& fname){

	tpie::file_stream<struct segment_t> in;
	in.open(fname, tpie::open::read_only);
	printf("size of stream: %6ld\n\n", in.size());
	while (in.can_read()) {
		segment_t item = in.read();
		print_item(item); printf("\n");
	}
}

/* copy infile name to outfile name. Assumes infile
 * is a valid tpie::file_stream and overwrites outfile
 */
void copystream(const std::string & infile,
		const std::string & outfile) {
	tpie::file_stream<struct segment_t> in;
	tpie::file_stream<struct segment_t> out;

	in.open(infile);
	out.open(outfile, tpie::open::write_only);
	while (in.can_read()) {
		segment_t item = in.read();
		out.write(item);
	}
}


/* core subsystems needed for using file_streams */
#define SUBSYS tpie::MEMORY_MANAGER | tpie::STREAMS


int main(int /*argc*/, char ** /*argv*/) {
	size_t memory_limit_mb = 50;

	/* start up TPIE subsystems, set memory limit */
	tpie::tpie_init(SUBSYS);
	tpie::get_memory_manager().set_limit(memory_limit_mb*1024*1024);

	std::string a = "test.in";
	std::string b = "test.out";
	cerr << "Writing " << a << endl;
	writestream(a, 10);
	cerr << "Copying  " << a << " to " << b << endl;
	copystream(a, b);
	cerr << "Reading  " << b << endl;
	readstream(b);

	/* wrap up */
	tpie::tpie_finish(SUBSYS);
	return EXIT_SUCCESS;
}