[Tarantool-patches] [PATCH 2/2] box: introduce a cfg handle to become syncro leader
Vladislav Shpilevoy
v.shpilevoy at tarantool.org
Sun Jul 5 02:03:42 MSK 2020
Hi! Thanks for the patch!
I didn't review it properly yet. Just one comment.
> diff --git a/src/box/box.cc b/src/box/box.cc
> index ca24b98ca..087710383 100644
> --- a/src/box/box.cc
> +++ b/src/box/box.cc
> @@ -945,6 +946,84 @@ box_set_replication_anon(void)
>
> }
>
> +void
> +box_set_replication_synchro_leader(void)
> +{
> + bool is_leader = cfg_geti("replication_synchro_leader");
> + /*
> + * For now no actions required when an instance stops
> + * being a leader. We should probably wait until txn_limbo
> + * becomes empty.
> + */
> + if (!is_leader)
> + return;
> + uint32_t former_leader_id = txn_limbo.instance_id;
> + if (former_leader_id == REPLICA_ID_NIL ||
> + former_leader_id == instance_id) {
> + return;
> + }
> +
> + /* Wait until pending confirmations/rollbacks reach us. */
> + double timeout = 2 * txn_limbo_confirm_timeout(&txn_limbo);
> + double start_tm = fiber_time();
> + while (!txn_limbo_is_empty(&txn_limbo)) {
> + if (fiber_time() - start_tm > timeout)
> + break;
> + fiber_sleep(0.001);
> + }
> +
> + if (!txn_limbo_is_empty(&txn_limbo)) {
> + int64_t lsns[VCLOCK_MAX];
> + int len = 0;
> + const struct vclock *vclock;
> + replicaset_foreach(replica) {
> + if (replica->relay != NULL &&
> + relay_get_state(replica->relay) != RELAY_OFF &&
> + !replica->anon) {
> + assert(!tt_uuid_is_equal(&INSTANCE_UUID,
> + &replica->uuid));
> + vclock = relay_vclock(replica->relay);
> + int64_t lsn = vclock_get(vclock,
> + former_leader_id);
> + lsns[len++] = lsn;
> + }
> + }
> + lsns[len++] = vclock_get(box_vclock, former_leader_id);
> + assert(len < VCLOCK_MAX);
> +
> + int64_t confirm_lsn = 0;
> + if (len >= replication_synchro_quorum) {
> + qsort(lsns, len, sizeof(int64_t), cmp_i64);
> + confirm_lsn = lsns[len - replication_synchro_quorum];
> + }
> +
Can the code below be moved to txn_limbo.c somehow? Doesn't look
right to touch the queue here.
> + struct txn_limbo_entry *e, *last_quorum = NULL;
> + struct txn_limbo_entry *rollback = NULL;
> + rlist_foreach_entry(e, &txn_limbo.queue, in_queue) {
> + if (txn_has_flag(e->txn, TXN_WAIT_ACK)) {
> + if (e->lsn <= confirm_lsn) {
> + last_quorum = e;
> + } else {
> + rollback = e;
> + break;
> + }
> + }
> + }
> +
> + if (last_quorum != NULL) {
> + confirm_lsn = last_quorum->lsn;
> + txn_limbo_write_confirm(&txn_limbo, confirm_lsn);
> + txn_limbo_read_confirm(&txn_limbo, confirm_lsn);
> + }
> + if (rollback != NULL) {
> + txn_limbo_write_rollback(&txn_limbo, rollback->lsn);
> + txn_limbo_read_rollback(&txn_limbo, rollback->lsn - 1);
> + }
> +
> + assert(txn_limbo_is_empty(&txn_limbo));
> + }
> +}
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