Method SelectServer

src/brpc/policy/round_robin_load_balancer.cpp:96–133

}

int RoundRobinLoadBalancer::SelectServer(const SelectIn& in, SelectOut* out) {
    butil::DoublyBufferedData<Servers, TLS>::ScopedPtr s;
    if (_db_servers.Read(&s) != 0) {
        return ENOMEM;
    }
    const size_t n = s->server_list.size();
    if (n == 0) {
        return ENODATA;
    }
    if (_cluster_recover_policy && _cluster_recover_policy->StopRecoverIfNecessary()) {
        if (_cluster_recover_policy->DoReject(s->server_list)) {
            return EREJECT;
        }
    }
    TLS tls = s.tls();
    if (tls.stride == 0) {
        tls.stride = bthread::prime_offset();
        // use random at first time, for the case of
        // use rr lb every time in new thread
        tls.offset = butil::fast_rand_less_than(n);
    }

    for (size_t i = 0; i < n; ++i) {
        tls.offset = (tls.offset + tls.stride) % n;
        const SocketId id = s->server_list[tls.offset].id;
        if (((i + 1) == n  // always take last chance
             || !ExcludedServers::IsExcluded(in.excluded, id))
            && IsServerAvailable(id, out->ptr)) {
            s.tls() = tls;
            return 0;
        }
    }
    if (_cluster_recover_policy) {
        _cluster_recover_policy->StartRecover();
    }
    s.tls() = tls;
    return EHOSTDOWN;
}

RoundRobinLoadBalancer* RoundRobinLoadBalancer::New(
    const butil::StringPiece& params) const {