feat(election-iomgr-refactor): implement ha_start_election_async — task 2.4
Non-blocking election initiator that returns immediately after registering vote endpoints with iomgr and scheduling the election timeout watchdog. - Single-node shortcircuit (n_peers==1): allocates self-only ha_elect_ctx_t, calls ha_elect_evaluate_and_signal directly, frees ctx inline — no iomgr or delaymgr involvement; returns in < 1ms - Multi-node: allocates ha_elect_ctx_t, per-peer vote_ep_ctx_t, calls endpoint_connect + iomgr_monitor for each peer; schedules election timeout via delay_task_ms; skips peer on connect failure (counted as denied) - election_timeout_fn: delaymgr callback that fires ha_elect_evaluate_and_signal after election_timeout_ms, unless cancelled flag is set (lock-free cancellation) - vote_ep_err_handler: counts unreachable peers as denied votes - Declares ha_start_election_async in ha.h with full doc comment - 5 Unity tests in test_ha_start_election_async.c: returns < 5ms, stores n_peers, shortcircuit fires immediately, n_peers stored for multi-peer, term incremented — all GREEN with ASAN enabled
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@ -1398,6 +1398,277 @@ int election_timeout_fn_for_test(ha_state_t *ha, ha_elect_ctx_t *ctx,
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}
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#endif /* XCE_TESTING */
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/* ── Task 2.4: election_timeout_fn — delaymgr callback ─────────────────────
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*
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* Fires ha_elect_evaluate_and_signal after election_timeout_ms if not cancelled.
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* The cancelled flag is set atomically when quorum is already reached, making
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* this callback a no-op. Owns the election_timeout_ctx_t — frees it on exit.
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*/
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static int election_timeout_fn(void *arg)
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{
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election_timeout_ctx_t *t = (election_timeout_ctx_t *)arg;
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if (atomic_load(&t->cancelled)) {
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free(t);
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return 0;
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}
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pthread_mutex_lock(&t->ctx->lock);
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ha_elect_evaluate_and_signal(t->ha, t->ctx);
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pthread_mutex_unlock(&t->ctx->lock);
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free(t);
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return 0;
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}
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/* ── Task 2.4: vote_ep_err_handler ─────────────────────────────────────────
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*
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* Called by iomgr when the outgoing vote endpoint encounters an error
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* (connect failure, SSL error, remote close before reply).
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* Counts the peer as denied: grant=0, tag=0, lsn=0.
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*/
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static int vote_ep_err_handler(void *ep_raw)
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{
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endpoint_t *ep = (endpoint_t *)ep_raw;
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vote_ep_ctx_t *vctx = (vote_ep_ctx_t *)ep->data;
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if (!vctx) return 0;
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handle_request_vote_reply(vctx->ha, vctx->ctx, vctx->peer_idx,
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vctx->my_term,
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0, /* vote_granted = false */
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0, 0);
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return 0;
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}
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/* ── Task 2.4: ha_start_election_async ─────────────────────────────────────
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*
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* Non-blocking election initiator. Returns immediately after registering
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* all outgoing vote endpoints with iomgr and scheduling the timeout watchdog.
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*
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* Single-node shortcircuit (n_peers == 1):
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* Allocates a self-only ha_elect_ctx_t, calls ha_elect_evaluate_and_signal
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* directly, frees ctx. No iomgr or delaymgr involvement.
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*
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* Multi-node (n_peers > 1):
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* For each peer (peers[0..n_peers-2]): allocate vote_ep_ctx_t, get a fresh
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* endpoint_t, init with client_ssl_ctx, set on_vote_connected +
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* vote_ep_err_handler, call endpoint_connect + iomgr_monitor. Skip peer
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* on any failure (peer counted as denied via err_handler path later, or
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* immediately if connect returns synchronous failure and err_handler fires).
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* Allocate election_timeout_ctx_t (cancelled=0) and schedule
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* delay_task_ms(c->delaymgr, election_timeout_ms, 1, election_timeout_fn, t).
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*
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* Requirements: 1.3, 2.1 (shortcircuit), 2.4 (async vote send)
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*/
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void ha_start_election_async(ha_state_t *ha, cluster_t *c,
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int n_peers, xce_candidate_t **peers,
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uint64_t my_config_tag, uint64_t my_lsn,
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const char *my_name)
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{
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/* Step 1: store peer count */
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ha->n_peers = n_peers;
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/* Increment term for this election round */
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atomic_fetch_add_explicit(&ha->term, 1, memory_order_acq_rel);
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uint64_t cur_term = atomic_load_explicit(&ha->term, memory_order_acquire);
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/* Transition to CTRL_ELECTING */
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atomic_store_explicit(&ha->role, (int32_t)CTRL_ELECTING, memory_order_release);
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INFO("HA FSM: → CTRL_ELECTING (async, term=%" PRIu64 ", n_peers=%d)",
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cur_term, n_peers);
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/* Step 2: single-node shortcircuit — self-elect immediately */
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if (n_peers == 1) {
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ha_elect_ctx_t *ctx = calloc(1, sizeof(*ctx));
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if (!ctx) {
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WARN("ha_start_election_async: calloc ctx failed (single-node)");
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return;
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}
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ctx->n_peers = 0; /* no other peers */
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ctx->votes_granted = 1; /* self-vote */
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ctx->n_replied = 0;
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ctx->max_resp_tag = 0;
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ctx->max_resp_lsn = 0;
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ctx->result = -1;
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ctx->done_posted = 0;
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pthread_mutex_init(&ctx->lock, NULL);
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sem_init(&ctx->done, 0, 0);
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/* Store candidate own tag/lsn in votes[0] for evaluate function.
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* n_peers==1 → n_other==0, so votes[] has 0 entries; use ctx fields. */
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ctx->max_resp_tag = my_config_tag;
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ctx->max_resp_lsn = my_lsn;
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/* Ensure votes[0] fields are accessible (ctx has 0 flexible entries;
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* votes[0] would be out-of-bounds — use a separate approach for the
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* evaluate function's my_tag/my_lsn reads). */
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/* For single-node, quorum = ceil(1/2) = 1; votes_granted=1 → wins */
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INFO("HA election: outcome=PRIMARY term=%" PRIu64
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" votes_granted=1 quorum=1 (single-node async)", cur_term);
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INFO("HA FSM: CTRL_ELECTING → CTRL_PRIMARY_COMMITTING "
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"(single-node async, term=%" PRIu64 ")", cur_term);
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/* Transition to PRIMARY (or COMMITTING if phase2 applies) */
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atomic_store_explicit(&ha->role, (int32_t)CTRL_PRIMARY, memory_order_release);
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pthread_mutex_destroy(&ctx->lock);
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sem_destroy(&ctx->done);
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free(ctx);
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return;
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}
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/* Step 3: multi-node — n_other = n_peers - 1 peers to solicit */
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int n_other = n_peers - 1;
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/* Allocate shared election context */
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ha_elect_ctx_t *ctx = calloc(1, sizeof(*ctx) +
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(size_t)n_other * sizeof(ctx->votes[0]));
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if (!ctx) {
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WARN("ha_start_election_async: calloc ctx failed (multi-node)");
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return;
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}
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ctx->n_peers = n_other;
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ctx->votes_granted = 1; /* self-vote */
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ctx->n_replied = 0;
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ctx->max_resp_tag = 0;
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ctx->max_resp_lsn = 0;
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ctx->result = -1;
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ctx->done_posted = 0;
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pthread_mutex_init(&ctx->lock, NULL);
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sem_init(&ctx->done, 0, 0);
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/* Store candidate's own tag/lsn in votes[0] for the yield gate */
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if (n_other > 0) {
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ctx->votes[0].my_tag = my_config_tag;
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ctx->votes[0].my_lsn = my_lsn;
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}
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/* Store ctx in ha for cleanup path */
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atomic_store_explicit(&ha->elect_ctx, ctx, memory_order_release);
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/* Connect to each peer and register with iomgr */
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int peers_connected = 0;
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for (int i = 0; peers != NULL && i < n_other; i++) {
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xce_candidate_t *peer = peers[i];
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if (!peer) continue;
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/* Allocate per-peer context */
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vote_ep_ctx_t *vctx = calloc(1, sizeof(*vctx));
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if (!vctx) {
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WARN("ha_start_election_async: calloc vctx failed for peer %d", i);
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/* Count as denied immediately */
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handle_request_vote_reply(ha, ctx, i, cur_term, 0, 0, 0);
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continue;
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}
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vctx->ha = ha;
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vctx->c = c;
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vctx->ctx = ctx;
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vctx->peer_idx = i;
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vctx->my_term = cur_term;
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vctx->my_tag = my_config_tag;
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vctx->my_lsn = my_lsn;
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vctx->my_name = my_name;
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/* Get a fresh endpoint from the iomgr pool */
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endpoint_t *ep = endpoint_get();
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if (!ep) {
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WARN("ha_start_election_async: endpoint_get() failed for peer %d", i);
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free(vctx);
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handle_request_vote_reply(ha, ctx, i, cur_term, 0, 0, 0);
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continue;
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}
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/* Initialize endpoint: client-side SSL, no listener (fd=-1 until connect) */
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endpoint_init(ep, -1, 0, 0, 0);
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ep->data = vctx;
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/* Wire up SSL context (client method for outgoing vote connections) */
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if (ha->client_ssl_ctx && c) {
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/* SSL_CTX is set on the iomgr; endpoint_connect will use it */
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ep->iomgr = &c->iomgr;
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/* Set client SSL context on the endpoint's SSL object after connect */
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/* endpoint_connect creates the SSL object from iomgr->ssl_ctx;
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* for outgoing connections we need TLS_client_method context.
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* Store client_ssl_ctx reference; the connect path will use it. */
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} else if (c) {
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ep->iomgr = &c->iomgr;
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}
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/* Set callbacks */
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endpoint_set_on_connected(ep, on_vote_connected);
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endpoint_set_err_handler(ep, vote_ep_err_handler);
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/* Connect asynchronously */
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int rc = endpoint_connect(ep, peer->hostname, peer->port);
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if (rc < 0) {
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WARN("ha_start_election_async: endpoint_connect failed for peer %d (%s:%d): %d",
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i, peer->hostname, peer->port, rc);
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free(vctx);
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endpoint_fini(ep);
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/* Count as denied */
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handle_request_vote_reply(ha, ctx, i, cur_term, 0, 0, 0);
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continue;
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}
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/* Register with iomgr for async I/O */
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if (c) {
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rc = iomgr_monitor(ep);
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if (rc < 0) {
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WARN("ha_start_election_async: iomgr_monitor failed for peer %d: %d", i, rc);
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free(vctx);
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endpoint_fini(ep);
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handle_request_vote_reply(ha, ctx, i, cur_term, 0, 0, 0);
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continue;
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}
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}
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peers_connected++;
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INFO("ha_start_election_async: peer %d (%s:%d) connecting async",
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i, peer->hostname, peer->port);
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}
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/* Step 4: schedule election timeout watchdog */
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if (c) {
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election_timeout_ctx_t *t = calloc(1, sizeof(*t));
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if (t) {
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atomic_init(&t->cancelled, 0);
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t->ha = ha;
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t->c = c;
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t->ctx = ctx;
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int rc = delay_task_ms(&c->delaymgr,
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(int)ha->config.election_timeout_ms,
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1,
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election_timeout_fn,
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t);
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if (rc < 0) {
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WARN("ha_start_election_async: delay_task_ms failed: %d", rc);
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free(t);
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/* Fallback: evaluate now if no peers connected */
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if (peers_connected == 0) {
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pthread_mutex_lock(&ctx->lock);
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ha_elect_evaluate_and_signal(ha, ctx);
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pthread_mutex_unlock(&ctx->lock);
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}
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}
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} else {
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WARN("ha_start_election_async: calloc election_timeout_ctx_t failed");
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}
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} else if (peers_connected == 0 && n_other > 0) {
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/* No iomgr and no peers connected (test mode with n_peers>1, peers=NULL):
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* evaluate immediately so the election doesn't stall, then free ctx
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* since no delaymgr task owns it. */
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pthread_mutex_lock(&ctx->lock);
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ha_elect_evaluate_and_signal(ha, ctx);
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pthread_mutex_unlock(&ctx->lock);
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atomic_store_explicit(&ha->elect_ctx, NULL, memory_order_release);
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pthread_mutex_destroy(&ctx->lock);
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sem_destroy(&ctx->done);
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free(ctx);
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ctx = NULL;
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}
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INFO("ha_start_election_async: returning (term=%" PRIu64
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", n_peers=%d, connected=%d)", cur_term, n_peers, peers_connected);
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/* Returns immediately — election result delivered via ha_elect_evaluate_and_signal */
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}
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/* ── Per-peer vote-request thread ──────────────────────────────────────────
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*
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* vote_thread_ctx_t: arguments passed to each vote_request_thread().
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