DM-3905 Quick hackfix to showcase how we could make distribution fair…

config/gobetween.toml

@@ -92,6 +92,7 @@ bind = "0.0.0.0:3000"
 [servers.udpsample]
 bind = "localhost:4000"
 protocol = "udp"
+balance="ipporthash1"
 
   [servers.udpsample.udp]
   max_responses = 1
@@ -115,7 +116,7 @@ protocol = "udp"
 #
 #bind = "localhost:3000"     #  (required) "<host>:<port>"
 #protocol = "tcp"            #  (required) "tcp" | "tls" | "udp"
-#balance = "weight"          #  (optional [weight]) "weight" | "leastconn" | "roundrobin" | "iphash" | "iphash1" | "leastbandwidth"
+#balance = "weight"          #  (optional [weight]) "weight" | "leastconn" | "roundrobin" | "iphash" | "iphash1" | "leastbandwidth" | "ipporthash1"
 #
 #max_connections = 0
 #client_idle_timeout = "10m"

src/balance/ipporthash1.go

@@ -0,0 +1,58 @@
+package balance
+
+/**
+ * ipporthash1.go - semi-consistent iphash balance impl also using the source prot
+ *
+ * Patched by Elias Weingärtner (elias.weingaertner@cumulocity.com)
+ */
+
+import (
+	"errors"
+	"hash/fnv"
+	"strconv"
+	"github.com/yyyar/gobetween/core"
+)
+
+/**
+ * Iphash balancer
+ */
+type IpPorthash1Balancer struct {
+}
+
+/**
+ * Elect backend using semi-consistent iphash strategy. This is naive implementation
+ * using Key+Node Hash Algorithm for stable sharding described at http://kennethxu.blogspot.com/2012/11/sharding-algorithm.html
+ * It survives removing nodes (removing stability), so that clients connected to backends that have not been removed stay
+ * untouched.
+
+
+ *
+ */
+func (b *IpPorthash1Balancer) Elect(context core.Context, backends []*core.Backend) (*core.Backend, error) {
+
+	if len(backends) == 0 {
+		return nil, errors.New("Can't elect backend, Backends empty")
+	}
+
+	var result *core.Backend
+	{
+		var bestHash uint32
+
+		for i, backend := range backends {
+			hasher := fnv.New32a()
+			hasher.Write(context.Ip())
+
+			portbytes := []byte(strconv.Itoa(context.Port()))
+			hasher.Write(portbytes)
+
+			hasher.Write([]byte(backend.Address()))
+			s32 := hasher.Sum32()
+			if s32 > bestHash {
+				bestHash = s32
+				result = backends[i]
+			}
+		}
+	}
+
+	return result, nil
+}

src/balance/registry.go

@@ -29,6 +29,8 @@ func init() {
 	typeRegistry["iphash"] = reflect.TypeOf(IphashBalancer{})
 	typeRegistry["iphash1"] = reflect.TypeOf(Iphash1Balancer{})
 	typeRegistry["leastbandwidth"] = reflect.TypeOf(LeastbandwidthBalancer{})
+	typeRegistry["ipporthash1"] = reflect.TypeOf(IpPorthash1Balancer{})
+
 }
 
 /**

src/manager/manager.go

@@ -483,7 +483,8 @@ func prepareConfig(name string, server config.Server, defaults config.Connection
 		"roundrobin",
 		"leastbandwidth",
 		"iphash1",
-		"iphash":
+		"iphash",
+		"ipporthash1":
 	case "":
 		server.Balance = "weight"
 	default: