/* See LICENSE file for copyright and license details. */
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <unistd.h>
#ifndef CAPACITY
# define CAPACITY (1 << 20)
#endif
int
main(int argc, const char *argv[])
{
static char buf[1 << 16];
int rw1[2], rw2[2], n = 0;
ssize_t r, p, w;
size_t sum = 0, totsum = 0;
struct timespec start, end;
double rate;
int capacity, flags;
if (!argc)
*argv = "limit";
dprintf(STDERR_FILENO, "Requested capacity: %i\n", CAPACITY);
if (pipe(rw1) || pipe(rw2))
goto fail;
capacity = fcntl(*rw1, F_SETPIPE_SZ, CAPACITY);
if (capacity < 0 || fcntl(*rw2, F_SETPIPE_SZ, capacity) != capacity)
goto fail;
dprintf(STDERR_FILENO, "Configured capacity: %i\n", capacity);
flags = fcntl(rw1[1], F_GETFL);
if (flags < 0 || fcntl(rw1[1], F_SETFL, flags |= O_NONBLOCK) < 0)
goto fail;
for (n = capacity, capacity = 0; n; n -= (int)r, capacity += (int)r) {
if ((r = write(rw1[1], buf, (size_t)n)) < 0) {
if (errno != EAGAIN)
goto fail;
n -= 1;
r = 0;
}
}
dprintf(STDERR_FILENO, "Supported capacity: %i\n", capacity);
if (fcntl(rw1[1], F_SETFL, flags ^= O_NONBLOCK) < 0)
goto fail;
if (clock_gettime(CLOCK_MONOTONIC, &start))
goto fail;
for (;;) {
r = splice(rw1[0], NULL, rw2[1], NULL, (size_t)capacity, 0);
if (r <= 0) {
if (r < 0)
goto fail;
goto done;
}
for (p = 0; p < r; p += w) {
w = splice(rw2[0], NULL, rw1[1], NULL, (size_t)(r - p), 0);
if (w <= 0) {
if (w < 0)
goto fail;
goto done;
}
}
sum += (size_t)r << 1;
if (++n == 100000) {
if (clock_gettime(CLOCK_MONOTONIC, &end))
goto fail;
n = 0;
start.tv_sec = end.tv_sec - start.tv_sec;
start.tv_nsec = end.tv_nsec - start.tv_nsec;
rate = (double)start.tv_nsec;
rate /= (double)1000000000.f;
rate += (double)start.tv_sec;
rate = (double)sum / rate;
rate /= (double)1000000000.f;
totsum += sum;
sum = 0;
dprintf(STDERR_FILENO, " %lf GB/s\033[K\n\033[A", rate);
start = end;
}
}
done:
return 0;
fail:
perror(*argv);
return 1;
}
