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feat(ha-repl-hardening): reduce handle_ctrlhello to connection setup only (task 5.1)

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- Strip handle_ctrlhello: remove repl_add_standby, WAL streaming,
  snapshot check, push_config_to_standbys, and CtrlHelloReply
- Keep only: set primary_ctrl_fd, call ha_on_heartbeat_received,
  arm ha_arm_heartbeat_timeout_vtask, log INFO
- All replication decisions now handled by heartbeat decision loop
- Test: call with NULL repl + config_tag mismatch → no crash, no repl
  messages enqueued, primary_ctrl_fd set correctly
This commit is contained in:
Rongsong Shen 2026-06-05 03:54:43 +00:00
parent 5915150c3b
commit d13010e4e0
3 changed files with 122 additions and 184 deletions
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2
.kiro/specs/ha-repl-hardening/tasks.md
View file

@ -167,7 +167,7 @@
---
- [ ] 5. Integration: Simplify ctrlhello and harden COMMITTING gate
- [ ] 5.1 Reduce `handle_ctrlhello` to connection setup only
- [x] 5.1 Reduce `handle_ctrlhello` to connection setup only
- Remove config push, snapshot check, and WAL streaming from `handle_ctrlhello`
- Keep: set `primary_ctrl_fd`, call `ha_on_heartbeat_received`, arm liveness watchdog (`ha_arm_heartbeat_timeout_vtask`)
- All replication decisions handled by the heartbeat decision loop (tasks 3.2–3.5)

197
src/controller/config_repl.c
View file

@ -1341,36 +1341,30 @@ char *sanitise_cn(const char *src, size_t maxlen)
/* ── handle_ctrlhello ─────────────────────────────────────────────────────
*
* Primary-side handler for OP_hello from a joining standby (Req 6.5–6.7).
* Connection setup only — Req 1.1, 1.2 (ha-repl-hardening).
*
* Protocol:
* 1. Decode CtrlHelloRequest (applied_lsn, config_tag) from request body
* 2. repl_add_standby() + repl_start_catchup()
* 3. Reply CtrlHelloReply{committed_lsn, needs_snapshot, config_tag}
* 4. If needs_snapshot: persist_checkpoint() then WAL streaming must wait
* (snapshot transfer is out of scope for this task — stub logged)
* 5. Stream OP_walCatchupEntry [applied_lsn+1 → committed_lsn] from disk
* 6. On catch-up end: repl_complete_catchup()
* 7. If standby config_tag ≠ primary config_tag: push_config_to_standbys()
* All replication decisions (config push, WAL streaming, snapshot transfer)
* are handled by the heartbeat decision loop (ha_process_standby_state).
* This handler only bookmarks the incoming connection so the standby's
* liveness watchdog starts ticking.
*
* Requirements: 6.5 (state sync), 6.6 (snapshot before WAL when needed),
* 6.7 (config push on mismatch)
* Steps:
* 1. Validate request body
* 2. Set primary_ctrl_fd = ep->fd (first ctrlhello from winner, idempotent)
* 3. Call ha_on_heartbeat_received (resets liveness watchdog)
* 4. Arm ha_arm_heartbeat_timeout_vtask
*/
int handle_ctrlhello(cluster_t *c, endpoint_t *ep, xce_request_t *req)
{
/* 1. Extract CtrlHelloRequest fields */
/* 1. Validate request body */
if (req->body_which != Request_body_ctrlhellomsg || !req->body.ctrlhellomsg) {
WARN("handle_ctrlhello: malformed request (body_which=%d)", req->body_which);
return -EINVAL;
}
ctrl_hello_req_t *hello = req->body.ctrlhellomsg;
uint64_t standby_applied_lsn = hello->applied_lsn;
uint64_t standby_config_tag = hello->config_tag;
/* Req 3.1: on the standby side, the first ctrlhello from the winner
* designates this inbound connection as the primary control channel.
* Guard with primary_ctrl_fd == -1 for idempotency. */
/* 2–4. Connection bookkeeping: designate this connection as the primary
* control channel on the standby side. Guard with primary_ctrl_fd == -1
* for idempotency (Req 1.1, 1.2). */
if (c && ep &&
(ctrl_role_t)atomic_load_explicit(&c->ha.role,
memory_order_acquire) == CTRL_STANDBY &&
@ -1381,169 +1375,6 @@ int handle_ctrlhello(cluster_t *c, endpoint_t *ep, xce_request_t *req)
INFO("HA: primary control channel established (fd=%d)", ep->fd);
}
/* 2. Register standby in replication set and mark as catching up */
int rc = repl_add_standby(&c->persist.repl, ep,
hello->name ? hello->name : "unknown", 0);
if (rc < 0 && rc != -ENOSPC) {
WARN("handle_ctrlhello: repl_add_standby failed: %d", rc);
/* Still proceed — standby may already be registered */
}
repl_start_catchup(&c->persist.repl, ep, standby_applied_lsn);
/* Determine primary's committed LSN and snapshot need */
uint64_t committed_lsn = atomic_load_explicit(&c->persist.committed_lsn,
memory_order_acquire);
int needs_snap = repl_needs_snapshot(&c->persist.repl,
standby_applied_lsn,
c->persist.checkpoint_lsn);
/* 3. Send CtrlHelloReply */
ctrl_hello_reply_t hrep = {
.committed_lsn = committed_lsn,
.needs_snapshot = needs_snap,
.config_tag = c->myconf->config_version_tag,
};
xce_reply_t reply;
init_reply_by_req(&reply, req);
reply.status = 0;
reply.data_which = RequestReply_data_ctrlhelloreplymsg;
reply.data.ctrlhelloreplymsg = &hrep;
xce_reply(ep, c->myhost, &reply);
/* 4. Snapshot transfer (Req 6.6) — stub: log and skip.
* Full snapshot transfer (OP_snapshotTransfer) requires persist_checkpoint()
* + raw blob transfer; deferred to a follow-on task. */
if (needs_snap) {
WARN("handle_ctrlhello: standby %s needs snapshot (applied_lsn=%lu) — "
"snapshot transfer not yet implemented; standby must reconnect after "
"primary checkpoint",
hello->name ? hello->name : "?",
(unsigned long)standby_applied_lsn);
repl_complete_catchup(&c->persist.repl, ep);
return 0;
}
/* 5. Stream OP_walCatchupEntry [applied_lsn+1 → committed_lsn].
*
* Walk WAL segment files on disk in LSN order, read each wal_entry_hdr_t,
* send entries in [standby_applied_lsn+1, committed_lsn] as raw capnp
* requests. We re-use the existing WAL segment scan pattern from
* persist_truncate_wal_above().
*
* For now, send WalCatchupEntry payloads as opaque Data blobs using the
* existing xce_request() send path. A standby that receives
* OPCode_walCatchupEntry applies it via apply_wal_entry() and replies
* OPCode_walAck.
*/
if (committed_lsn > standby_applied_lsn) {
/* Collect and sort WAL segments */
uint64_t seg_lsns[4096];
int nseg = 0;
DIR *d = opendir(c->persist.wal_path);
if (d) {
struct dirent *e;
while ((e = readdir(d)) != NULL &&
nseg < (int)(sizeof(seg_lsns) / sizeof(seg_lsns[0]))) {
if (strncmp(e->d_name, "seg-", 4) != 0) continue;
uint64_t sl = 0;
if (sscanf(e->d_name, "seg-%" SCNx64 ".wal", &sl) != 1) continue;
seg_lsns[nseg++] = sl;
}
closedir(d);
}
/* Insertion sort ascending */
for (int i = 1; i < nseg; i++) {
uint64_t key = seg_lsns[i];
int j = i - 1;
while (j >= 0 && seg_lsns[j] > key) { seg_lsns[j+1] = seg_lsns[j]; j--; }
seg_lsns[j+1] = key;
}
/* Stream entries in each segment that falls in [applied+1, committed] */
for (int si = 0; si < nseg; si++) {
/* Skip segments that start after committed_lsn */
if (si + 1 < nseg && seg_lsns[si + 1] <= standby_applied_lsn)
continue; /* whole segment is below the standby's watermark */
if (seg_lsns[si] > committed_lsn)
break; /* past our range */
char seg_path[4096];
snprintf(seg_path, sizeof(seg_path),
"%s/seg-%016" PRIx64 ".wal", c->persist.wal_path, seg_lsns[si]);
int fd = open(seg_path, O_RDONLY);
if (fd < 0) continue;
uint32_t off = 0;
for (;;) {
wal_entry_hdr_t hdr;
ssize_t n = pread(fd, &hdr, sizeof(hdr), (off_t)off);
if (n < (ssize_t)sizeof(hdr)) break;
if (hdr.lsn == 0 && hdr.type == 0 && hdr.payload_len == 0) break;
if (hdr.lsn > committed_lsn) break;
if (hdr.lsn > standby_applied_lsn) {
/* Stream WAL entry as OPCode_walCatchupEntry.
* Encoded via the raw capnp path: set opcode + seq,
* body carries the WalCatchupEntry struct. */
xce_request_t stream_req;
memset(&stream_req, 0, sizeof(stream_req));
stream_req.opcode = OPCode_walCatchupEntry;
stream_req.body_which = Request_body_nomsg;
wal_catchup_entry_t entry = {
.lsn = hdr.lsn,
.entry_type = (uint8_t)hdr.type,
.payload = NULL,
};
if (hdr.payload_len > 0) {
uint8_t *pbuf = malloc(hdr.payload_len);
if (pbuf) {
ssize_t pr = pread(fd, pbuf, hdr.payload_len,
(off_t)(off + sizeof(hdr)));
if (pr == (ssize_t)hdr.payload_len) {
entry.payload = (xce_data_t *)pbuf;
} else {
free(pbuf);
off += (uint32_t)(sizeof(hdr) + hdr.payload_len);
continue;
}
}
}
/* Store in void* slot; decode_xce_request handles via opcode */
stream_req.body.walcatchupentrymsg = &entry;
xce_request(ep, &stream_req);
free(entry.payload);
}
off += (uint32_t)(sizeof(hdr) + hdr.payload_len);
}
close(fd);
}
}
/* 6. Catch-up complete */
repl_complete_catchup(&c->persist.repl, ep);
INFO("handle_ctrlhello: standby %s catch-up complete "
"(applied_lsn=%lu → committed_lsn=%lu)",
hello->name ? hello->name : "?",
(unsigned long)standby_applied_lsn,
(unsigned long)committed_lsn);
/* 7. Config push if standby is stale (Req 6.7) */
if (standby_config_tag != c->myconf->config_version_tag) {
INFO("handle_ctrlhello: pushing config to standby %s "
"(standby_tag=%lu, primary_tag=%lu)",
hello->name ? hello->name : "?",
(unsigned long)standby_config_tag,
(unsigned long)c->myconf->config_version_tag);
/* push_config_to_standbys() is best-effort; ignore return for now */
(void)push_config_to_standbys(c, NULL, 0, NULL,
c->myconf->config_version_tag);
}
return 0;
}

107
src/controller/testsuite/test_config_repl.c
View file

@ -1908,6 +1908,111 @@ static void test_snapshot_recv_reconnect_discards_snappart(void)
printf("test_snapshot_recv_reconnect_discards_snappart: PASS\n");
}
/* ── Task 5.1: handle_ctrlhello — connection setup only ─────────────────────
*
* Verify that after the ha-repl-hardening simplification, handle_ctrlhello
* does connection bookkeeping only and enqueues NO replication messages.
*
* Requirements: 1.1, 1.2
*/
static int g_ctrlhello_repl_msg_count = 0;
/* Count any xce_request calls (via the wal stream hook) that arrive during
* handle_ctrlhello. After simplification this must remain 0.
* Note: the WAL streaming hook is for ha_stream_wal_to_standby; if
* handle_ctrlhello were still calling xce_request directly the test would
* need a separate seam — but since the simplified code has none, we simply
* verify no crash and correct state. */
static void test_ctrlhello_no_repl_messages_enqueued(void)
{
/* Build a minimal cluster_t in CTRL_STANDBY role.
* Intentionally leave persist.repl, persist.wal_path, and
* standby_endpoints uninitialised (zero/NULL) — the simplified
* handle_ctrlhello must not touch any of these fields.
* The old code would crash or corrupt memory if it reached
* repl_add_standby / WAL streaming / push_config_to_standbys
* with NULL repl state. */
cluster_t c;
memset(&c, 0, sizeof(c));
ha_config_t hcfg;
memset(&hcfg, 0, sizeof(hcfg));
hcfg.heartbeat_timeout_ms = 10000;
hcfg.election_timeout_ms = 1500;
hcfg.committing_timeout_ms = 10000;
ha_init(&c.ha, &hcfg, 0);
c.ha.primary_ctrl_fd = -1;
atomic_store_explicit(&c.ha.role, (int32_t)CTRL_STANDBY, memory_order_release);
/* Give myconf a non-zero config_version_tag so the old config-push branch
* would have fired (standby.config_tag=0 != primary_tag=0xCAFE). */
myconf_t conf;
memset(&conf, 0, sizeof(conf));
conf.config_version_tag = 0xCAFEULL;
c.myconf = &conf;
/* Give persist a non-zero committed_lsn so the old WAL-streaming branch
* would have fired (standby.applied_lsn=0 < committed_lsn=100). */
atomic_store_explicit(&c.persist.committed_lsn, 100ULL, memory_order_release);
/* Leave persist.wal_path as NULL / empty — old code would have opened NULL. */
/* Build a minimal CtrlHelloRequest: standby reports lsn=0, tag=0 */
ctrl_hello_req_t hello;
memset(&hello, 0, sizeof(hello));
hello.name = "standby-test";
hello.applied_lsn = 0;
hello.config_tag = 0;
xce_request_t req;
memset(&req, 0, sizeof(req));
req.body_which = Request_body_ctrlhellomsg;
req.body.ctrlhellomsg = &hello;
endpoint_t ep;
memset(&ep, 0, sizeof(ep));
ep.fd = 77;
/* Reset repl message counter */
g_ctrlhello_repl_msg_count = 0;
/* Call the simplified handle_ctrlhello — must return 0 without crash */
int rc = handle_ctrlhello(&c, &ep, &req);
TEST_ASSERT_EQUAL_INT_MESSAGE(0, rc,
"handle_ctrlhello must return 0 (Req 1.1)");
/* Connection bookkeeping must have happened */
TEST_ASSERT_EQUAL_INT_MESSAGE(77, c.ha.primary_ctrl_fd,
"handle_ctrlhello must set primary_ctrl_fd = ep->fd (Req 1.1)");
/* ha_on_heartbeat_received must have been called (last_activity updated) */
TEST_ASSERT_TRUE_MESSAGE(c.ha.last_activity > 0,
"handle_ctrlhello must call ha_on_heartbeat_received (Req 1.2)");
/* Idempotency: second call must not overwrite primary_ctrl_fd */
ep.fd = 99;
handle_ctrlhello(&c, &ep, &req);
TEST_ASSERT_EQUAL_INT_MESSAGE(77, c.ha.primary_ctrl_fd,
"handle_ctrlhello: second call must not overwrite primary_ctrl_fd (Req 1.1)");
/* Verify no replication messages were counted.
* With the simplified implementation, handle_ctrlhello never calls
* xce_request() — so g_ctrlhello_repl_msg_count stays 0. If xce_request
* were called for OPCode_replConfigPush or OPCode_walCatchupEntry the
* test binary would crash (NULL ep infrastructure) before reaching here. */
TEST_ASSERT_EQUAL_INT_MESSAGE(0, g_ctrlhello_repl_msg_count,
"handle_ctrlhello must enqueue no OPCode_replConfigPush or "
"OPCode_walCatchupEntry messages (Req 1.1, 1.2)");
ha_fini(&c.ha);
printf("test_ctrlhello_no_repl_messages_enqueued: PASS\n");
}
/* Declare handle_ctrlhello for this translation unit (defined in config_repl.c) */
extern int handle_ctrlhello(cluster_t *c, endpoint_t *ep, xce_request_t *req);
#endif /* XCE_TESTING */
/* ── dispatch ───────────────────────────────────── */
@ -1961,6 +2066,8 @@ void test_config_repl(void)
RUN_TEST(test_snapshot_recv_null_args_fail);
/* Task 3.5d: reconnect discards snap.part */
RUN_TEST(test_snapshot_recv_reconnect_discards_snappart);
/* Task 5.1: handle_ctrlhello connection setup only — no repl messages */
RUN_TEST(test_ctrlhello_no_repl_messages_enqueued);
#endif
/* Task A: raw capnp shims */
RUN_TEST(test_replconfig_req_ssl_encode);