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/*
* (C) Copyright 1996- ECMWF.
*
* This software is licensed under the terms of the Apache Licence Version 2.0
* which can be obtained at http://www.apache.org/licenses/LICENSE-2.0.
* In applying this licence, ECMWF does not waive the privileges and immunities
* granted to it by virtue of its status as an intergovernmental organisation nor
* does it submit to any jurisdiction.
*/
#include <fcntl.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include <cerrno>
#include <cassert>
#include <cstdio>
#include <cstdlib>
#include <iostream>
#include "eckit/eckit.h"
#include "eckit/exception/Exceptions.h"
#include "eckit/log/Bytes.h"
#include "eckit/memory/MMap.h"
#include "eckit/testing/Test.h"
using namespace std;
using namespace eckit;
using namespace eckit::testing;
namespace eckit::test {
//----------------------------------------------------------------------------------------------------------------------
int get_pagesize() {
int pagesize;
errno = 0ll;
if ((pagesize = sysconf(_SC_PAGE_SIZE)) == -1) {
if (errno == 0) {
printf("PAGE_SIZE not supported by sysconf implementation\n");
}
else {
perror("sysconf error.");
}
exit(EXIT_FAILURE);
}
return pagesize;
}
// |--------------------------------|--------------------------------|
// ^2G limit ^4Gb
// ^--------^ mapped region
#define SIZE_2G 2147483648 // 2^31
#define TOTAL_SIZE 2 * SIZE_2G // 4Gb file
#define ELEMS_2G (SIZE_2G / sizeof(int))
#define NELEMS 8 * 1024
#define MAP_SIZE (NELEMS * sizeof(int))
#define ELEM_LW (ELEMS_2G - NELEMS / 2)
#define ELEM_UP (ELEM_LW + NELEMS)
#define SIZE_UP (ELEM_UP * sizeof(int))
#define SIZE_LW (ELEM_LW * sizeof(int))
//----------------------------------------------------------------------------------------------------------------------
CASE("Test memory map") {
// compute the 2GB limit and its number of pages
int pagesize = get_pagesize();
size_t nbpages_2gb = SIZE_2G / pagesize;
EXPECT(nbpages_2gb * pagesize == SIZE_2G);
std::cout << Bytes(SIZE_2G) << " are " << nbpages_2gb << " memory pages" << std::endl;
// mmapped array of int's
int* map;
// make temporary file name
int fd;
char filename[] = "mmaped.XXXXXX";
if ((fd = ::mkstemp(filename)) == -1) {
perror("cannot create temporary file"), exit(EXIT_FAILURE);
}
// file is opened in mkstemp, so this is not needed
// if( ( fd = ::open(filename, O_RDWR | O_CREAT | O_TRUNC, (mode_t)0600) ) == -1 )
// perror("Error opening file"), exit(EXIT_FAILURE);
// stretch the file size to the size of the (mmapped) array of ints
if ((long long)::lseek(fd, TOTAL_SIZE - 1, SEEK_SET) < 0) {
perror("Error calling lseek() to 'stretch' the file"), exit(EXIT_FAILURE);
}
// write something to the end of the file to actually resize it correctly
if (::write(fd, "", 1) != 1) {
close(fd), perror("Error writing last byte of the file"), exit(EXIT_FAILURE);
}
// map the file
std::cout << "mapping " << Bytes(MAP_SIZE) << " from " << Bytes(SIZE_LW) << " to " << Bytes(SIZE_UP) << std::endl;
if ((map = (int*)MMap::mmap(0, MAP_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, SIZE_LW)) == MAP_FAILED) {
close(fd), perror("Error mmapping the file"), exit(EXIT_FAILURE);
}
// write to file as if it were memory
for (int i = 0; i < NELEMS; ++i) {
map[i] = 2 * i;
}
// free the mmapped memory
if (MMap::munmap(map, MAP_SIZE) == -1) {
perror("Error un-mmapping the file"), exit(EXIT_FAILURE);
}
// close the file
if (close(fd) == -1) {
perror("Error closing file descriptot"), exit(EXIT_FAILURE);
}
// test that the contents of the file are correct
// remove the file -- its large!
if (::unlink(filename) == -1) {
perror("Error removing the file"), exit(EXIT_FAILURE);
}
}
//----------------------------------------------------------------------------------------------------------------------
} // namespace eckit::test
int main(int argc, char** argv) {
return run_tests(argc, argv);
}
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