consistent hash load balance

cluster/loadbalance/consistent_hash.go

@@ -0,0 +1,164 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package loadbalance
+
+import (
+	"crypto/md5"
+	"encoding/json"
+	"fmt"
+	"hash/crc32"
+	"regexp"
+	"sort"
+	"strconv"
+	"strings"
+
+	"github.com/apache/dubbo-go/cluster"
+	"github.com/apache/dubbo-go/common/constant"
+	"github.com/apache/dubbo-go/common/extension"
+	"github.com/apache/dubbo-go/protocol"
+)
+
+const (
+	ConsistentHash = "consistenthash"
+	HashNodes      = "hash.nodes"
+	HashArguments  = "hash.arguments"
+)
+
+var selectors = make(map[string]*ConsistentHashSelector)
+var re = regexp.MustCompile(constant.COMMA_SPLIT_PATTERN)
+
+func init() {
+	extension.SetLoadbalance(ConsistentHash, NewConsistentHash)
+}
+
+type ConsistentHashLoadBalance struct {
+}
+
+func NewConsistentHash() cluster.LoadBalance {
+	return &ConsistentHashLoadBalance{}
+}
+
+func (lb *ConsistentHashLoadBalance) Select(invokers []protocol.Invoker, invocation protocol.Invocation) protocol.Invoker {
+	methodName := invocation.MethodName()
+	key := invokers[0].GetUrl().ServiceKey() + "." + methodName
+
+	// hash the invokers
+	bs := make([]byte, 0)
+	for _, invoker := range invokers {
+		b, err := json.Marshal(invoker)
+		if err != nil {
+			panic(fmt.Sprintf("parse json failed:%s", err.Error()))
+		}
+		bs = append(bs, b...)
+	}
+	hashCode := crc32.ChecksumIEEE(bs)
+	selector, ok := selectors[key]
+	if !ok || selector.hashCode != hashCode {
+		selectors[key] = NewConsistentHashSelector(invokers, methodName, hashCode)
+		selector = selectors[key]
+	}
+	return selector.Select(invocation)
+}
+
+type Uint32Slice []uint32
+
+func (s Uint32Slice) Len() int {
+	return len(s)
+}
+
+func (s Uint32Slice) Less(i, j int) bool {
+	return s[i] < s[j]
+}
+
+func (s Uint32Slice) Swap(i, j int) {
+	s[i], s[j] = s[j], s[i]
+}
+
+type ConsistentHashSelector struct {
+	hashCode        uint32
+	replicaNum      int
+	virtualInvokers map[uint32]protocol.Invoker
+	keys            Uint32Slice
+	argumentIndex   []int
+}
+
+func NewConsistentHashSelector(invokers []protocol.Invoker, methodName string,
+	hashCode uint32) *ConsistentHashSelector {
+	if len(invokers) == 0 {
+		panic("none of invokers")
+	}
+
+	selector := &ConsistentHashSelector{}
+	selector.virtualInvokers = make(map[uint32]protocol.Invoker)
+	selector.hashCode = hashCode
+	url := invokers[0].GetUrl()
+	selector.replicaNum = int(url.GetMethodParamInt(methodName, HashNodes, 160))
+	indices := re.Split(url.GetMethodParam(methodName, HashArguments, "0"), -1)
+	for _, index := range indices {
+		i, err := strconv.Atoi(index)
+		if err != nil {
+			panic(err)
+		}
+		selector.argumentIndex = append(selector.argumentIndex, i)
+	}
+	for _, invoker := range invokers {
+		u := invoker.GetUrl()
+		address := u.Ip + ":" + u.Port
+		for i := 0; i < selector.replicaNum/4; i++ {
+			digest := md5.Sum([]byte(address + strconv.Itoa(i)))
+			for j := 0; j < 4; j++ {
+				key := selector.hash(digest, j)
+				selector.keys = append(selector.keys, key)
+				selector.virtualInvokers[key] = invoker
+			}
+		}
+	}
+	sort.Sort(selector.keys)
+	return selector
+}
+
+func (c *ConsistentHashSelector) Select(invocation protocol.Invocation) protocol.Invoker {
+	key := c.toKey(invocation.Arguments())
+	digest := md5.Sum([]byte(key))
+	return c.selectForKey(c.hash(digest, 0))
+}
+
+func (c *ConsistentHashSelector) toKey(args []interface{}) string {
+	var sb strings.Builder
+	for i := range c.argumentIndex {
+		if i >= 0 && i < len(args) {
+			fmt.Fprint(&sb, args[i].(string))
+		}
+	}
+	return sb.String()
+}
+
+func (c *ConsistentHashSelector) selectForKey(hash uint32) protocol.Invoker {
+	idx := sort.Search(len(c.keys), func(i int) bool {
+		return c.keys[i] >= hash
+	})
+	if idx == len(c.keys) {
+		idx = 0
+	}
+	return c.virtualInvokers[c.keys[idx]]
+}
+
+func (c *ConsistentHashSelector) hash(digest [16]byte, i int) uint32 {
+	return uint32((digest[3+i*4]&0xFF)<<24) | uint32((digest[2+i*4]&0xFF)<<16) |
+		uint32((digest[1+i*4]&0xFF)<<8) | uint32(digest[i*4]&0xFF)&0xFFFFFFF
+}

cluster/loadbalance/consistent_hash_test.go

@@ -0,0 +1,106 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package loadbalance
+
+import (
+	"context"
+	"testing"
+
+	"github.com/stretchr/testify/suite"
+
+	"github.com/apache/dubbo-go/cluster"
+	"github.com/apache/dubbo-go/common"
+	"github.com/apache/dubbo-go/protocol"
+	"github.com/apache/dubbo-go/protocol/invocation"
+)
+
+func TestConsistentHashSelectorSuite(t *testing.T) {
+	suite.Run(t, new(consistentHashSelectorSuite))
+}
+
+type consistentHashSelectorSuite struct {
+	suite.Suite
+	selector *ConsistentHashSelector
+}
+
+func (s *consistentHashSelectorSuite) SetupTest() {
+	var invokers []protocol.Invoker
+	url, _ := common.NewURL(context.TODO(),
+		"dubbo://192.168.1.0:20000/org.apache.demo.HelloService?methods.echo.hash.arguments=0,1")
+	invokers = append(invokers, protocol.NewBaseInvoker(url))
+	s.selector = NewConsistentHashSelector(invokers, "echo", 999944)
+}
+
+func (s *consistentHashSelectorSuite) TestToKey() {
+	result := s.selector.toKey([]interface{}{"username", "age"})
+	s.Equal(result, "usernameage")
+}
+
+func (s *consistentHashSelectorSuite) TestSelectForKey() {
+	url1, _ := common.NewURL(context.TODO(), "dubbo://192.168.1.0:8080")
+	url2, _ := common.NewURL(context.TODO(), "dubbo://192.168.1.0:8081")
+	s.selector.virtualInvokers = make(map[uint32]protocol.Invoker)
+	s.selector.virtualInvokers[99874] = protocol.NewBaseInvoker(url1)
+	s.selector.virtualInvokers[9999945] = protocol.NewBaseInvoker(url2)
+	s.selector.keys = []uint32{99874, 9999945}
+	result := s.selector.selectForKey(9999944)
+	s.Equal(result.GetUrl().String(), "dubbo://192.168.1.0:8081?")
+}
+
+func TestConsistentHashLoadBalanceSuite(t *testing.T) {
+	suite.Run(t, new(consistentHashLoadBalanceSuite))
+}
+
+type consistentHashLoadBalanceSuite struct {
+	suite.Suite
+	url1     common.URL
+	url2     common.URL
+	url3     common.URL
+	invokers []protocol.Invoker
+	invoker1 protocol.Invoker
+	invoker2 protocol.Invoker
+	invoker3 protocol.Invoker
+	lb       cluster.LoadBalance
+}
+
+func (s *consistentHashLoadBalanceSuite) SetupTest() {
+	var err error
+	s.url1, err = common.NewURL(context.TODO(), "dubbo://192.168.1.0:8080/org.apache.demo.HelloService?methods.echo.hash.arguments=0,1")
+	s.NoError(err)
+	s.url2, err = common.NewURL(context.TODO(), "dubbo://192.168.1.0:8081/org.apache.demo.HelloService?methods.echo.hash.arguments=0,1")
+	s.NoError(err)
+	s.url3, err = common.NewURL(context.TODO(), "dubbo://192.168.1.0:8082/org.apache.demo.HelloService?methods.echo.hash.arguments=0,1")
+	s.NoError(err)
+
+	s.invoker1 = protocol.NewBaseInvoker(s.url1)
+	s.invoker2 = protocol.NewBaseInvoker(s.url2)
+	s.invoker3 = protocol.NewBaseInvoker(s.url3)
+
+	s.invokers = append(s.invokers, s.invoker1, s.invoker2, s.invoker3)
+	s.lb = NewConsistentHash()
+}
+
+func (s *consistentHashLoadBalanceSuite) TestSelect() {
+	args := []interface{}{"name", "password", "age"}
+	invoker := s.lb.Select(s.invokers, invocation.NewRPCInvocation("echo", args, nil))
+	s.Equal(invoker.GetUrl().Location, "192.168.1.0:8080")
+
+	args = []interface{}{"ok", "abc"}
+	invoker = s.lb.Select(s.invokers, invocation.NewRPCInvocation("echo", args, nil))
+	s.Equal(invoker.GetUrl().Location, "192.168.1.0:8082")
+}

common/constant/default.go

@@ -67,3 +67,7 @@ const (
 	APP_DYNAMIC_CONFIGURATORS_CATEGORY = "appdynamicconfigurators"
 	PROVIDER_CATEGORY                  = "providers"
 )
+
+const (
+	COMMA_SPLIT_PATTERN = "\\s*[,]+\\s*"
+)

go.mod

@@ -51,3 +51,5 @@ require (
 	google.golang.org/grpc v1.22.1
 	gopkg.in/yaml.v2 v2.2.2
 )
+
+go 1.13