| 99 | } |
| 100 | |
| 101 | int DynPartLoadBalancer::SelectServer(const SelectIn& in, SelectOut* out) { |
| 102 | butil::DoublyBufferedData<Servers>::ScopedPtr s; |
| 103 | if (_db_servers.Read(&s) != 0) { |
| 104 | return ENOMEM; |
| 105 | } |
| 106 | const size_t n = s->server_list.size(); |
| 107 | if (n == 0) { |
| 108 | return ENODATA; |
| 109 | } |
| 110 | if (n == 1) { |
| 111 | if (Socket::Address(s->server_list[0].id, out->ptr) == 0) { |
| 112 | return 0; |
| 113 | } |
| 114 | return EHOSTDOWN; |
| 115 | } |
| 116 | int64_t total_weight = 0; |
| 117 | std::pair<SocketUniquePtr, int64_t> ptrs[8]; |
| 118 | int nptr = 0; |
| 119 | bool exclusion = true; |
| 120 | do { |
| 121 | for (size_t i = 0; i < n; ++i) { |
| 122 | const SocketId id = s->server_list[i].id; |
| 123 | if ((!exclusion || !ExcludedServers::IsExcluded(in.excluded, id)) |
| 124 | && Socket::Address(id, &ptrs[nptr].first) == 0) { |
| 125 | int w = schan::GetSubChannelWeight(ptrs[nptr].first->user()); |
| 126 | total_weight += w; |
| 127 | RELEASE_ASSERT_VERBOSE(nptr < 8, "Not supported yet"); |
| 128 | ptrs[nptr].second = total_weight; |
| 129 | ++nptr; |
| 130 | } |
| 131 | } |
| 132 | if (nptr != 0) { |
| 133 | break; |
| 134 | } |
| 135 | if (!exclusion) { |
| 136 | return EHOSTDOWN; |
| 137 | } |
| 138 | exclusion = false; |
| 139 | CHECK_EQ(0, total_weight); |
| 140 | total_weight = 0; |
| 141 | } while (1); |
| 142 | |
| 143 | if (nptr == 1) { |
| 144 | out->ptr->reset(ptrs[0].first.release()); |
| 145 | return 0; |
| 146 | } |
| 147 | uint32_t r = butil::fast_rand_less_than(total_weight); |
| 148 | for (int i = 0; i < nptr; ++i) { |
| 149 | if (ptrs[i].second > r) { |
| 150 | out->ptr->reset(ptrs[i].first.release()); |
| 151 | return 0; |
| 152 | } |
| 153 | } |
| 154 | return EHOSTDOWN; |
| 155 | } |
| 156 | |
| 157 | DynPartLoadBalancer* DynPartLoadBalancer::New(const butil::StringPiece&) const { |
| 158 | return new (std::nothrow) DynPartLoadBalancer; |