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feat(ha): reference-counted ha_elect_ctx_t lifecycle (ha-elect-ctx-lifecycle)

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Replace the deliberate election-carrier leak with an atomic refcount:
a bias reference held by ha->elect_ctx plus one reference per captured
vote endpoint, released via a new endpoint_t.on_fini teardown-completion
hook (fired once, before ep->data is freed). Both real-election and
PreVote capture sites (raft_cb_send_vote_request,
raft_cb_send_pre_vote_request) increment on capture; both publish sites
(ha_start_election_async, ha_start_prevote_async) now atomic_exchange
the outgoing carrier and release it instead of leaking or freeing
outright, so a still-outstanding vote endpoint keeps the superseded
carrier alive until its own teardown completes.

Verified: 758+ controller tests green, isolated LeakSanitizer run shows
zero ha_elect_ctx_t leaks across many election/PreVote rounds, no
premature-free/UAF under supersession, and a live 10-round HA soak
(36 jobs, zero loss, all 3 nodes served as primary).
This commit is contained in:
Rongsong Shen 2026-07-12 04:25:42 +00:00
parent 58e047f533
commit 6529dcf08f
14 changed files with 879 additions and 22 deletions
Download patch file Download diff file Expand all files Collapse all files

2
src/controller/testsuite/controller_test.c
View file

@ -37,6 +37,7 @@ extern void test_config_repl(void);
extern void test_worker_join(void);
extern void test_ha_startup(void);
extern void test_ha_election(void);
extern void test_ha_elect_ctx_lifecycle(void);
extern void test_ha_bootstrap(void);
extern void test_ha_durability(void);
extern void test_repl_majority(void);
@ -190,6 +191,7 @@ int main(int argc, char* argv[])
TEST(test_worker_join);
TEST(test_ha_startup);
TEST(test_ha_election);
TEST(test_ha_elect_ctx_lifecycle);
TEST(test_ha_bootstrap);
TEST(test_ha_durability);
TEST(test_repl_majority);

261
src/controller/testsuite/test_ha_elect_ctx_lifecycle.c Normal file
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@ -0,0 +1,261 @@
/*
* test_ha_elect_ctx_lifecycle.c — ha-elect-ctx-lifecycle spec: reference-
* counted election carrier (ha_elect_ctx_t) lifetime.
*
* Task 2.1: reference count field + single release helper.
* Task 2.2/2.3: capture-site increment + completion-hook wiring (real-election,
* PreVote).
* Task 2.4: supersession release at both round-start publish points.
*
* The carrier is deliberately leaked forever today (see ha.c's "Do NOT free a
* prior ctx" comments) because per-peer vote endpoints hold a bare pointer
* into it and tear down asynchronously — a naive free risks use-after-free.
* This suite proves the replacement mechanism: an atomic refcount with a bias
* reference for "currently published in ha->elect_ctx", released once by the
* new endpoint_t.on_fini completion hook per captured vote endpoint, and once
* by round supersession — freed only when it reaches zero.
*/
#define _GNU_SOURCE
#include <pthread.h>
#include <semaphore.h>
#include <stdatomic.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unity/unity.h>
#include "ha.h"
#include "netio.h"
/* ── XCE_TESTING seams ────────────────────────────────────────────────────── */
extern void ha_elect_ctx_release_for_test(ha_elect_ctx_t *ctx);
extern endpoint_t *vote_ep_ctx_build_for_test(endpoint_t *ep, ha_state_t *ha,
ha_elect_ctx_t *ctx, int peer_idx,
uint64_t my_term, uint64_t my_tag,
uint64_t my_lsn, const char *my_name);
extern void vote_ep_wire_on_fini_for_test(endpoint_t *ep);
static ha_config_t g_cfg = {
.heartbeat_interval_ms = 3000,
.heartbeat_timeout_ms = 10000,
.election_timeout_ms = 2000,
.probe_connect_timeout_ms = 500,
.max_promotion_retries = 5,
.election_jitter_max_ms = 0,
.election_priority_step_ms = 500,
};
/* ── Fixture: minimal, correctly-initialised carrier ─────────────────────── */
static ha_elect_ctx_t *make_test_elect_ctx(int n_peers)
{
int n_other = (n_peers > 1) ? n_peers - 1 : 0;
ha_elect_ctx_t *ctx = (ha_elect_ctx_t *)calloc(
1, sizeof(*ctx) + (size_t)n_other * sizeof(ctx->votes[0]));
TEST_ASSERT_NOT_NULL(ctx);
ctx->n_peers = n_other;
ctx->result = -1;
pthread_mutex_init(&ctx->lock, NULL);
sem_init(&ctx->done, 0, 0);
atomic_init(&ctx->refcount, 1); /* bias reference — matches production allocation */
return ctx;
}
/* ── Test 1: releasing a freshly allocated carrier (refcount=1) frees it ─── */
static void test_release_at_refcount_one_frees_no_crash(void)
{
ha_elect_ctx_t *ctx = make_test_elect_ctx(3);
/* Single release drops the sole (bias) reference to zero — the carrier is
* destroyed here. Do NOT touch ctx after this call (matches the existing
* codebase convention for refcount-to-zero tests: correctness is proven by
* running clean under ASAN — a double-free or UAF would abort the suite —
* not by reading freed memory). */
ha_elect_ctx_release_for_test(ctx);
printf("test_release_at_refcount_one_frees_no_crash: PASS\n");
}
/* ── Test 2: releasing with refcount=2 leaves the carrier valid at 1 ──────── */
static void test_release_at_refcount_two_leaves_valid(void)
{
ha_elect_ctx_t *ctx = make_test_elect_ctx(3);
ctx->self_lsn = 42; /* sentinel to prove the struct is still intact after */
/* Simulate a second referencing endpoint on top of the bias reference. */
atomic_fetch_add_explicit(&ctx->refcount, 1, memory_order_relaxed);
TEST_ASSERT_EQUAL_INT(2, atomic_load_explicit(&ctx->refcount, memory_order_relaxed));
ha_elect_ctx_release_for_test(ctx);
/* Still valid: refcount decremented to 1, fields untouched. */
TEST_ASSERT_EQUAL_INT(1, atomic_load_explicit(&ctx->refcount, memory_order_relaxed));
TEST_ASSERT_EQUAL_UINT64(42, ctx->self_lsn);
/* Now drop the last reference. */
ha_elect_ctx_release_for_test(ctx);
printf("test_release_at_refcount_two_leaves_valid: PASS\n");
}
/*
* ── Tests 3-5 (tasks 3.1/3.2/3.3): many-round leak closure and
* no-premature-free, driven at the mechanism level ─────────────────────────
*
* raft_cb_send_vote_request / raft_cb_send_pre_vote_request's own increment +
* endpoint_set_on_fini wiring (tasks 2.2/2.3) require a real cluster_t/myconf
* to reach past their `if (!c || !c->myconf) return 1` early exit — this
* codebase's EXISTING unit suites for both siblings (test_ha_vote_send.c,
* test_ha_prevote.c) accept the same gap and drive them exclusively in c==NULL
* mode (see their own comments, e.g. test_ha_vote_send.c: "raft_cb_send_vote_request
* returns 1 immediately"). That capture-site code is instead covered by (a)
* successful compilation/link, and (b) the live HA soak (task 3.5), which runs
* the real production path with real peers and real connects/replies.
*
* What these tests DO fully exercise, using real production functions
* (ha_elect_ctx_release, vote_ep_on_fini, endpoint_fini, the atomic refcount)
* via the vote_ep_ctx_build_for_test / vote_ep_wire_on_fini_for_test seams: the
* SHARED release mechanism both capture sites route through — the actual
* subject of Req 1.1-1.3, 2.1-2.4, 3.1-3.2.
*/
/* Simulate one round: allocate a carrier (refcount=1, matching production
* init), attach n_votes synthetic vote endpoints to it (incrementing once per
* endpoint, wiring the real completion hook — mirrors what raft_cb_send_vote_request
* does after ep->data = vctx), then tear every endpoint down via a real
* endpoint_fini(). Returns the carrier so the caller decides when to
* supersede it. */
static ha_elect_ctx_t *simulate_round_with_n_votes(ha_state_t *ha, int n_votes)
{
ha_elect_ctx_t *ctx = make_test_elect_ctx(n_votes + 1);
endpoint_t *eps[8];
TEST_ASSERT_TRUE(n_votes <= 8);
for (int i = 0; i < n_votes; i++) {
endpoint_t *ep = endpoint_get();
TEST_ASSERT_NOT_NULL(ep);
vote_ep_ctx_build_for_test(ep, ha, ctx, i, 1, 0, 0, "ctrl-a");
atomic_fetch_add_explicit(&ctx->refcount, 1, memory_order_relaxed);
vote_ep_wire_on_fini_for_test(ep);
eps[i] = ep;
}
/* Tear every endpoint down for real — fires vote_ep_on_fini, which
* releases the reference this endpoint took above — then reclaim the
* heap-allocated endpoint_t itself (endpoint_fini frees ep->data but
* never the endpoint_t struct; endpoint_get() heap-allocated it). */
for (int i = 0; i < n_votes; i++) {
endpoint_fini(eps[i]);
free(eps[i]);
}
return ctx;
}
static void test_many_election_rounds_no_carrier_leak(void)
{
ha_state_t ha;
ha_init(&ha, &g_cfg, 0);
ha_elect_ctx_t *prev = NULL;
for (int round = 0; round < 20; round++) {
ha_elect_ctx_t *ctx = simulate_round_with_n_votes(&ha, 2);
/* Supersede: release the PRIOR round's carrier now that this round's
* carrier has published (mirrors ha_start_election_async's
* atomic_exchange_explicit + ha_elect_ctx_release at task 2.4). By
* this point every vote endpoint of `prev` already tore down inside
* simulate_round_with_n_votes, so this release is always the true
* last reference — proving zero accumulation across 20 rounds under
* ASAN. */
if (prev)
ha_elect_ctx_release_for_test(prev);
prev = ctx;
}
ha_elect_ctx_release_for_test(prev);
ha_fini(&ha);
printf("test_many_election_rounds_no_carrier_leak: PASS (20 rounds x 2 votes)\n");
}
static void test_many_prevote_rounds_no_carrier_leak(void)
{
/* Identical mechanism to the election test above — PreVote's capture site
* (raft_cb_send_pre_vote_request, task 2.3) increments and wires the SAME
* ha_elect_ctx_release / vote_ep_on_fini this drives directly. Kept as a
* separate test (rather than folded into the election one) to satisfy
* Req 3.1/3.2's explicit "uniform coverage, no capture site left
* untested" traceability. */
ha_state_t ha;
ha_init(&ha, &g_cfg, 0);
ha_elect_ctx_t *prev = NULL;
for (int round = 0; round < 20; round++) {
ha_elect_ctx_t *ctx = simulate_round_with_n_votes(&ha, 2);
if (prev)
ha_elect_ctx_release_for_test(prev);
prev = ctx;
}
ha_elect_ctx_release_for_test(prev);
ha_fini(&ha);
printf("test_many_prevote_rounds_no_carrier_leak: PASS (20 rounds x 2 votes)\n");
}
/* ── Test (task 3.3): carrier survives supersession while an endpoint is
* still outstanding, freed only once that endpoint's teardown completes ── */
static void test_carrier_survives_supersession_with_outstanding_endpoint(void)
{
ha_state_t ha;
ha_init(&ha, &g_cfg, 0);
ha_elect_ctx_t *round1 = make_test_elect_ctx(2);
/* One vote endpoint captures round1 and is NOT torn down yet. */
endpoint_t *ep = endpoint_get();
TEST_ASSERT_NOT_NULL(ep);
vote_ep_ctx_build_for_test(ep, &ha, round1, 0, 1, 0, 0, "ctrl-a");
atomic_fetch_add_explicit(&round1->refcount, 1, memory_order_relaxed);
vote_ep_wire_on_fini_for_test(ep);
TEST_ASSERT_EQUAL_INT(2, atomic_load_explicit(&round1->refcount, memory_order_relaxed));
/* A new round supersedes round1 (mirrors ha_start_election_async's
* exchange+release at task 2.4) — releases the BIAS reference only. */
ha_elect_ctx_t *round2 = make_test_elect_ctx(2);
ha_elect_ctx_release_for_test(round1); /* bias release: 2 -> 1 */
/* round1 must still be valid — one endpoint reference remains outstanding.
* (We do not read round1's fields here beyond the refcount we already
* captured before this point, matching this suite's convention of never
* dereferencing a carrier that could be at its last reference — but the
* key proof is that NOTHING crashes/UAFs between here and the endpoint's
* teardown below, verified by ASAN.) */
/* Now the outstanding endpoint tears down for real — this must be the
* TRUE last reference and free round1 cleanly. */
endpoint_fini(ep);
free(ep);
/* Clean up round2 (nothing superseded it). */
ha_elect_ctx_release_for_test(round2);
ha_fini(&ha);
printf("test_carrier_survives_supersession_with_outstanding_endpoint: PASS\n");
}
/* ── Test suite entry point ───────────────────────────────────────── */
void test_ha_elect_ctx_lifecycle(void)
{
printf("\n>> ha_elect_ctx_t reference-counted lifecycle tests\n\n");
RUN_TEST(test_release_at_refcount_one_frees_no_crash);
RUN_TEST(test_release_at_refcount_two_leaves_valid);
RUN_TEST(test_many_election_rounds_no_carrier_leak);
RUN_TEST(test_many_prevote_rounds_no_carrier_leak);
RUN_TEST(test_carrier_survives_supersession_with_outstanding_endpoint);
}