waitForDistribution makes RPC's on the greeter client until 3 RPC's follow the same 1:1:1 address ratio for the peer. Returns an error if fails to do so before context timeout.
(ctx context.Context, client hwpb.GreeterClient)
| 132 | // the same 1:1:1 address ratio for the peer. Returns an error if fails to do so |
| 133 | // before context timeout. |
| 134 | func waitForDistribution(ctx context.Context, client hwpb.GreeterClient) error { |
| 135 | wantPeers := []string{ |
| 136 | // Server 1 is listening on both IPv4 and IPv6 loopback addresses. |
| 137 | // Since the IPv6 address comes first in the resolver list, it will be |
| 138 | // given higher priority. |
| 139 | fmt.Sprintf("[::1]:%d", port1), |
| 140 | // Server 2 is listening only on the IPv4 loopback address. |
| 141 | fmt.Sprintf("127.0.0.1:%d", port2), |
| 142 | // Server 3 is listening only on the IPv6 loopback address. |
| 143 | fmt.Sprintf("[::1]:%d", port3), |
| 144 | } |
| 145 | const iterationsToVerify = 3 |
| 146 | const backendCount = 3 |
| 147 | requestCounter := 0 |
| 148 | |
| 149 | for ctx.Err() == nil { |
| 150 | result := make(map[string]int) |
| 151 | badRatioSeen := false |
| 152 | for i := 1; i <= iterationsToVerify && !badRatioSeen; i++ { |
| 153 | for j := 0; j < backendCount; j++ { |
| 154 | var peer peer.Peer |
| 155 | resp, err := client.SayHello(ctx, &hwpb.HelloRequest{ |
| 156 | Name: fmt.Sprintf("request:%d", requestCounter), |
| 157 | }, grpc.Peer(&peer)) |
| 158 | requestCounter++ |
| 159 | if err != nil { |
| 160 | return fmt.Errorf("RPC failed: %v", err) |
| 161 | } |
| 162 | log.Print("Greeting:", resp.GetMessage()) |
| 163 | |
| 164 | peerAddr := peer.Addr.String() |
| 165 | if !slices.Contains(wantPeers, peerAddr) { |
| 166 | return fmt.Errorf("peer address was not one of %q, got: %v", strings.Join(wantPeers, ", "), peerAddr) |
| 167 | } |
| 168 | result[peerAddr]++ |
| 169 | time.Sleep(time.Millisecond) |
| 170 | } |
| 171 | |
| 172 | // Verify the results of this iteration. |
| 173 | for _, count := range result { |
| 174 | if count == i { |
| 175 | continue |
| 176 | } |
| 177 | badRatioSeen = true |
| 178 | break |
| 179 | } |
| 180 | if !badRatioSeen { |
| 181 | log.Print("Got iteration with 1:1:1 distribution between addresses.") |
| 182 | } |
| 183 | } |
| 184 | if !badRatioSeen { |
| 185 | return nil |
| 186 | } |
| 187 | } |
| 188 | return fmt.Errorf("timeout waiting for 1:1:1 distribution between addresses %v", wantPeers) |
| 189 | } |