xce_failover_rotate reconnected with endpoint_fini+endpoint_init+endpoint_connect
but never re-bound ep->iomgr (reset by endpoint_init) nor re-armed the owner/
msg/err handlers + iomgr_monitor. endpoint_connect then dereferenced a NULL
iomgr (->ssl_ctx) → SEGV at netio.c:672 during live master failover. Added
xce_ctx_reconnect() in xcectx.c that mirrors xcecli_start's establishment
(without restarting iomgr/vtaskmgr or touching ctx->state); rotate delegates to
it. Found via live 3-node E2E. bug-610.
Four bugs fixed:
1. persist.c: array job WAL loop aborted after index [0] when replication
returned -ENODEV (no standbys). Loop guard now uses the return value of
persist_wal_sync_append() which is 0 on local-disk success regardless of
replication status.
2. join.c: WAL-recovered worker slot (status=UNAVAIL) caused add_worker() to
return -EEXIST on reconnect. New EEXIST path in handle_worker_join() looks
up the existing slot by name, updates its endpoint, and clears UNAVAIL so
the normal hook/reply/on_worker_join flow proceeds.
3. xcectx.c: cbuf_get() in xce_hello() blocked indefinitely when the TCP
connection dropped because no error handler was registered. Added
handle_disconnect() which sets ctx->state=XCE_CTX_ERR and calls
cbuf_tryput(-ECONNRESET) to unblock the waiter, allowing
checking_connection() to detect the failure and rejoin.
4. cluster.c: persist_recover() was called before cluster_build_resources()
populated resmgr, causing restore_worker() → add_hostattrs_resvals() to
fail with EEXIST noise. Moved persist_recover() to after HOOK_AFTER_EVENT
so resmgr is fully populated before WAL replay.
