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/* SPDX-License-Identifier: LGPL-2.1+ */
#include <fcntl.h>
#include <math.h>
#include <pthread.h>
#include <stdio.h>
#include "time-util.h"
#include "util.h"
#include "cachunker.h"
#define BUFFER_SIZE (64*1024)
#define CHUNKS_MAX 1000000
#define THREADS_MAX 16
#define RUNTIME_NSEC UINT64_C(2000000000)
struct thread_info {
pthread_t id;
CaChunker chunker;
unsigned *histogram;
unsigned n_chunks;
int random_fd;
uint64_t until;
};
static void* process(void *q) {
struct thread_info *t = q;
size_t previous = 0;
for (;;) {
uint8_t buffer[BUFFER_SIZE], *p;
ssize_t l;
if (t->until < now(CLOCK_MONOTONIC))
return NULL;
l = read(t->random_fd, buffer, sizeof(buffer));
assert_se(l == sizeof(buffer));
p = buffer;
for (;;) {
size_t n;
n = ca_chunker_scan(&t->chunker, p, l);
if (n == (size_t) -1) {
previous += l;
break;
}
assert_se(n <= (size_t) l);
assert_se(previous + n >= t->chunker.chunk_size_min);
assert_se(previous + n <= t->chunker.chunk_size_max);
t->histogram[previous + n] ++;
t->n_chunks ++;
p += n;
l -= n;
previous = 0;
}
}
}
static void draw(unsigned *histogram, size_t n) {
#define N_BUCKETS 30
#define N_HEIGHT 69
unsigned buckets[N_BUCKETS] = {};
unsigned highest = 0;
size_t i;
for (i = 0; i < n; i++)
buckets[i * N_BUCKETS / n] += histogram[i];
for (i = 0; i < N_BUCKETS; i++)
if (buckets[i] > highest)
highest = buckets[i];
for (i = 0; i < N_BUCKETS; i++) {
unsigned k, j;
k = buckets[i] * N_HEIGHT / highest;
printf("%10zu ", (i+1) * n / N_BUCKETS -1);
for (j = 0; j < k; j++)
putchar('#');
putchar('\n');
}
}
static void run(size_t pick, size_t *ret_avg) {
CaChunker chunker = CA_CHUNKER_INIT;
unsigned *histogram, n_chunks = 0;
struct thread_info threads[THREADS_MAX] = {};
uint64_t until, sum = 0;
size_t i;
int fd, r;
ca_chunker_set_size(&chunker, 0, pick, 0);
histogram = new0(unsigned, chunker.chunk_size_max+1);
assert_se(histogram);
log_info("Min/Avg/Max = %zu/%zu/%zu (discriminator=%zu)",
chunker.chunk_size_min,
chunker.chunk_size_avg,
chunker.chunk_size_max,
chunker.discriminator);
fd = open("/dev/urandom", O_CLOEXEC|O_RDONLY);
assert_se(fd >= 0);
until = now(CLOCK_MONOTONIC) + RUNTIME_NSEC;
for (i = 0; i < THREADS_MAX; i++) {
threads[i].chunker = chunker;
threads[i].histogram = new0(unsigned, chunker.chunk_size_max+1);
assert_se(threads[i].histogram);
threads[i].random_fd = fd;
threads[i].until = until;
r = pthread_create(&threads[i].id, NULL, process, threads + i);
assert_se(r == 0);
}
for (i = 0; i < THREADS_MAX; i++) {
size_t j;
r = pthread_join(threads[i].id, NULL);
assert_se(r == 0);
for (j = 0; j <= chunker.chunk_size_max; j++) {
histogram[j] += threads[i].histogram[j];
sum += threads[i].histogram[j] * j;
}
n_chunks += threads[i].n_chunks;
free(threads[i].histogram);
}
log_info("Generated %u chunks.", n_chunks);
log_info("Effective average is %" PRIu64 ".", sum / n_chunks);
*ret_avg = sum / n_chunks;
draw(histogram, chunker.chunk_size_max+1);
free(histogram);
safe_close(fd);
return;
}
int main(int argc, char* argv[]) {
size_t avg, start, end, step;
if (argc > 1) {
start = 4096;
end = 1024*1024;
step = 4*1024;
} else {
start = CA_CHUNK_SIZE_AVG_DEFAULT;
end = CA_CHUNK_SIZE_AVG_DEFAULT+1;
step = 1;
}
for (avg = start; avg < end; avg += step) {
size_t effective_avg;
double factor;
run(avg, &effective_avg);
factor = (double) effective_avg / (double) avg;
printf("%zu\t%zu\t%g\n", avg, effective_avg, factor);
log_error("Asked for average: %zu — Got average: %zu — Factor: %g", avg, effective_avg, factor);
}
return 0;
}
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