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raft: transfer information about group0 liveness in direct_fd_ping

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Add a new variant of the reply to the direct_fd_ping which specifies
whether the local group0 is alive or not, and start actively using it.

There is no need to introduce a cluster feature. Due to how our
serialization framework works, nodes which do not recognize the new
variant will treat it as the existing std::monostate. The std::monostate
means "the node and group0 is alive"; nodes before the changes in this
commit would send a std::monostate anyway, so this is completely
transparent for the old nodes.
This commit is contained in:
Piotr Dulikowski
2023-10-30 16:05:11 +01:00
parent a1ebfcf006
commit a8ee4d543a
3 changed files with 29 additions and 7 deletions
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6
idl/raft.idl.hh
View File

@@ -121,8 +121,12 @@ struct wrong_destination {
raft::server_id reached_id;
};
struct group_liveness_info {
bool group0_alive;
};
struct direct_fd_ping_reply {
std::variant<std::monostate, service::wrong_destination> result;
std::variant<std::monostate, service::wrong_destination, service::group_liveness_info> result;
};
verb [[with_client_info, cancellable]] direct_fd_ping (raft::server_id dst_id) -> service::direct_fd_ping_reply;

6
service/raft/group0_fwd.hh
View File

@@ -75,8 +75,12 @@ struct wrong_destination {
raft::server_id reached_id;
};
struct group_liveness_info {
bool group0_alive;
};
struct direct_fd_ping_reply {
std::variant<std::monostate, wrong_destination> result;
std::variant<std::monostate, wrong_destination, group_liveness_info> result;
};
} // namespace service

24
service/raft/raft_group_registry.cc
View File

@@ -297,15 +297,27 @@ void raft_group_registry::init_rpc_verbs() {
// XXX: update address map here as well?
if (_my_id != dst) {
co_return direct_fd_ping_reply {
return make_ready_future<direct_fd_ping_reply>(direct_fd_ping_reply {
.result = wrong_destination {
.reached_id = _my_id,
},
};
});
}
co_return direct_fd_ping_reply {
.result = std::monostate{},
};
return container().invoke_on(0, [] (raft_group_registry& me) -> future<direct_fd_ping_reply> {
bool group0_alive = false;
if (me._group0_id) {
auto* group0_server = me.find_server(*me._group0_id);
if (group0_server && group0_server->is_alive()) {
group0_alive = true;
}
}
co_return direct_fd_ping_reply {
.result = service::group_liveness_info{
.group0_alive = group0_alive,
}
};
});
});
}
@@ -513,6 +525,8 @@ future<bool> direct_fd_pinger::ping(direct_failure_detector::pinger::endpoint_id
rslog.trace("ping(id = {}, ip_addr = {}): wrong destination (reached {})",
dst_id, *addr, wrong_dst->reached_id);
co_return false;
} else if (auto* info = std::get_if<group_liveness_info>(&reply.result)) {
co_return info->group0_alive;
}
} catch (seastar::rpc::closed_error&) {
co_return false;