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/*
* Ouroboros - Copyright (C) 2016 - 2026
*
* Unit tests for link capacity estimation
*
* Dimitri Staessens <dimitri@ouroboros.rocks>
* Sander Vrijders <sander@ouroboros.rocks>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License
* version 2.1 as published by the Free Software Foundation.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., http://www.fsf.org/about/contact/.
*/
#include "../cap.c"
#include <test/test.h>
#include <inttypes.h>
#include <stdbool.h>
#define TICK (50 * 1000ULL) /* 50 us between packets */
#define LEN 1000ULL /* default packet size (B) */
#define QLEN (8 * LEN) /* steady backlog (bytes) */
#define RATE (LEN * BILLION / TICK) /* LEN per TICK = 20 MB/s */
#define SHP_LEN 1250ULL /* shaped-link packet (B) */
#define SHP_STEP 20 /* packets per shaped window */
#define SHP_RATE (SHP_LEN * BILLION / (SHP_STEP * TICK))
/* Draining CAP_N_MIN of these outlasts CAP_T_MAX without a gap. */
#define LOW_STEP (250 * TICK) /* 12.5 ms between packets */
#define LOW_RATE (LEN * BILLION / LOW_STEP)
/* Within the quarter-log2 band the wire code publishes. */
static bool rate_is_near(uint64_t got,
uint64_t exp)
{
return got >= exp - exp / 8 && got <= exp + exp / 8;
}
static int test_cap_est_clear(void)
{
struct cap_est e;
size_t i;
TEST_START();
cap_clear(&e);
if (cap_rate(&e) != 0) {
printf("Fresh estimator not unknown.\n");
goto fail;
}
for (i = 1; i <= 40; i++)
cap_update_at(&e, QLEN, LEN, i * TICK);
if (cap_rate(&e) == 0) {
printf("No estimate to clear.\n");
goto fail;
}
cap_clear(&e);
if (cap_rate(&e) != 0) {
printf("Clear did not drop the estimate.\n");
goto fail;
}
TEST_SUCCESS();
return TEST_RC_SUCCESS;
fail:
TEST_FAIL();
return TEST_RC_FAIL;
}
/* 1000 B every 50 us, ring steady at 8: drain = 20 MB/s. */
static int test_cap_est_busy_window(void)
{
struct cap_est e;
size_t i;
TEST_START();
cap_clear(&e);
for (i = 1; i <= 40; i++)
cap_update_at(&e, QLEN, LEN, i * TICK);
if (!rate_is_near(cap_rate(&e), RATE)) {
printf("Estimated rate: exp %" PRIu64 ", got %" PRIu64 ".\n",
(uint64_t) RATE, cap_rate(&e));
goto fail;
}
TEST_SUCCESS();
return TEST_RC_SUCCESS;
fail:
TEST_FAIL();
return TEST_RC_FAIL;
}
static int test_cap_est_idle_tolerated(void)
{
struct cap_est e;
size_t i;
TEST_START();
cap_clear(&e);
for (i = 1; i <= 40; i++)
cap_update_at(&e, i == 21 ? 0 : QLEN, LEN, i * TICK);
if (!rate_is_near(cap_rate(&e), RATE)) {
printf("Grazed window: exp %" PRIu64 ", got %" PRIu64 ".\n",
(uint64_t) RATE, cap_rate(&e));
goto fail;
}
TEST_SUCCESS();
return TEST_RC_SUCCESS;
fail:
TEST_FAIL();
return TEST_RC_FAIL;
}
static int test_cap_est_mostly_idle_rejects(void)
{
struct cap_est e;
size_t i;
TEST_START();
cap_clear(&e);
for (i = 1; i <= 100; i++)
cap_update_at(&e, 0, LEN, i * TICK);
if (cap_rate(&e) != 0) {
printf("Idle ring estimated %" PRIu64 ".\n", cap_rate(&e));
goto fail;
}
TEST_SUCCESS();
return TEST_RC_SUCCESS;
fail:
TEST_FAIL();
return TEST_RC_FAIL;
}
/* 1000 B every 100 us: 10 slots/ms closes on a 2 ms window. */
static int test_cap_est_slow_link_extends(void)
{
struct cap_est e;
size_t i;
TEST_START();
cap_clear(&e);
for (i = 1; i <= 30; i++)
cap_update_at(&e, QLEN, LEN, i * 2 * TICK);
if (!rate_is_near(cap_rate(&e), RATE / 2)) {
printf("Slow link: exp %" PRIu64 ", got %" PRIu64 ".\n",
(uint64_t) (RATE / 2), cap_rate(&e));
goto fail;
}
TEST_SUCCESS();
return TEST_RC_SUCCESS;
fail:
TEST_FAIL();
return TEST_RC_FAIL;
}
/* 1250 B every ms; one empty observation per 20 packets. */
static int test_cap_est_shaped_link(void)
{
struct cap_est e;
size_t i;
TEST_START();
cap_clear(&e);
for (i = 1; i <= 100; i++)
cap_update_at(&e, i % SHP_STEP == 0 ? 0 : 6 * SHP_LEN,
SHP_LEN, i * SHP_STEP * TICK);
if (!rate_is_near(cap_rate(&e), SHP_RATE)) {
printf("Shaped link: exp %" PRIu64 ", got %" PRIu64 ".\n",
(uint64_t) SHP_RATE, cap_rate(&e));
goto fail;
}
TEST_SUCCESS();
return TEST_RC_SUCCESS;
fail:
TEST_FAIL();
return TEST_RC_FAIL;
}
/* Open a window, trickle 4 slots, then ~200 ms of silence. */
static int test_cap_est_stale_discard(void)
{
struct cap_est e;
uint64_t t;
size_t i;
TEST_START();
cap_clear(&e);
for (i = 1; i <= 5; i++)
cap_update_at(&e, QLEN, LEN, i * CAP_T_MIN);
t = 205 * CAP_T_MIN;
cap_update_at(&e, QLEN, LEN, t);
if (cap_rate(&e) != 0) {
printf("Gap window estimated %" PRIu64 ".\n", cap_rate(&e));
goto fail;
}
for (i = 1; i <= 40; i++)
cap_update_at(&e, QLEN, LEN, t + i * TICK);
if (!rate_is_near(cap_rate(&e), RATE)) {
printf("Post-gap: exp %" PRIu64 ", got %" PRIu64 ".\n",
(uint64_t) RATE, cap_rate(&e));
goto fail;
}
TEST_SUCCESS();
return TEST_RC_SUCCESS;
fail:
TEST_FAIL();
return TEST_RC_FAIL;
}
static int test_cap_est_empty_start_no_raise(void)
{
struct cap_est e;
size_t i;
TEST_START();
cap_clear(&e);
cap_update_at(&e, 0, LEN, CAP_T_MIN);
for (i = 1; i <= 40; i++)
cap_update_at(&e, QLEN, LEN, CAP_T_MIN + i * TICK);
if (cap_rate(&e) != 0) {
printf("Empty-start window raised to %" PRIu64 ".\n",
cap_rate(&e));
goto fail;
}
for (i = 41; i <= 60; i++)
cap_update_at(&e, QLEN, LEN, CAP_T_MIN + i * TICK);
if (!rate_is_near(cap_rate(&e), RATE)) {
printf("Backlogged window: exp %" PRIu64 ", got %" PRIu64
".\n", (uint64_t) RATE, cap_rate(&e));
goto fail;
}
TEST_SUCCESS();
return TEST_RC_SUCCESS;
fail:
TEST_FAIL();
return TEST_RC_FAIL;
}
/*
* Max filter: fast attack on a high sample, slow release on the
* lower samples from a halved packet size (10 MB/s).
*/
static int test_cap_est_max_filter(void)
{
struct cap_est e;
uint64_t high;
size_t i;
TEST_START();
cap_clear(&e);
for (i = 1; i <= 40; i++)
cap_update_at(&e, QLEN, LEN, i * TICK);
high = cap_rate(&e);
if (!rate_is_near(high, RATE)) {
printf("Attack missed: exp %" PRIu64 ", got %" PRIu64 ".\n",
(uint64_t) RATE, high);
goto fail;
}
for (i = 41; i <= 80; i++)
cap_update_at(&e, QLEN, LEN / 2, i * TICK);
if (cap_rate(&e) >= high) {
printf("Release did not decay: %" PRIu64 ".\n", cap_rate(&e));
goto fail;
}
if (cap_rate(&e) <= RATE / 2) {
printf("Release collapsed to %" PRIu64 ".\n", cap_rate(&e));
goto fail;
}
TEST_SUCCESS();
return TEST_RC_SUCCESS;
fail:
TEST_FAIL();
return TEST_RC_FAIL;
}
/* No window close within CAP_T_MIN of the last one. */
static int test_cap_est_gate(void)
{
struct cap_est e;
size_t i;
TEST_START();
cap_clear(&e);
cap_update_at(&e, QLEN, LEN, CAP_T_MIN);
for (i = 0; i < 5; i++)
cap_update_at(&e, QLEN, LEN, CAP_T_MIN + CAP_T_MIN / 2);
if (e.t_gate != CAP_T_MIN) {
printf("Window closed inside the gate.\n");
goto fail;
}
if (LOAD_RELAXED(&e.c_pkt) != 6) {
printf("Gated packets not counted.\n");
goto fail;
}
TEST_SUCCESS();
return TEST_RC_SUCCESS;
fail:
TEST_FAIL();
return TEST_RC_FAIL;
}
/*
* A link slow enough that CAP_N_MIN packets take longer than
* CAP_T_MAX to drain still publishes, as long as the sender keeps
* offering: only silence voids a window.
*/
static int test_cap_est_low_rate_publishes(void)
{
struct cap_est e;
size_t i;
TEST_START();
cap_clear(&e);
for (i = 1; i <= 20; i++)
cap_update_at(&e, QLEN, LEN, i * LOW_STEP);
if (!rate_is_near(cap_rate(&e), LOW_RATE)) {
printf("Low rate: exp %" PRIu64 ", got %" PRIu64 ".\n",
(uint64_t) LOW_RATE, cap_rate(&e));
goto fail;
}
TEST_SUCCESS();
return TEST_RC_SUCCESS;
fail:
TEST_FAIL();
return TEST_RC_FAIL;
}
int cap_test(int argc,
char ** argv)
{
int ret = 0;
(void) argc;
(void) argv;
ret |= test_cap_est_clear();
ret |= test_cap_est_busy_window();
ret |= test_cap_est_idle_tolerated();
ret |= test_cap_est_mostly_idle_rejects();
ret |= test_cap_est_slow_link_extends();
ret |= test_cap_est_shaped_link();
ret |= test_cap_est_stale_discard();
ret |= test_cap_est_empty_start_no_raise();
ret |= test_cap_est_max_filter();
ret |= test_cap_est_gate();
ret |= test_cap_est_low_rate_publishes();
return ret;
}
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