通过Watcher监听和更新服务，避免每次重新获取OnlineMessageRelay服务，减少请求ETCD次数，解决下面的warn

{"level":"warn","ts":"2022-04-22T17:37:26.375+0800","logger":"etcd-client","caller":"v3@v3.5.2/retry_interceptor.go:62","msg":"retrying of unary invoker failed","target":"etcd-endpoints://0xc00cf55c00/127.0.0.1:2379","attempt":0,"error":"rpc error: code = DeadlineExceeded desc = latest balancer error: last connection error: connection closed before server preface received"}

internal/push/logic/init.go

@@ -10,11 +10,13 @@ import (
 	"Open_IM/pkg/common/config"
 	"Open_IM/pkg/common/constant"
 	"Open_IM/pkg/common/kafka"
+	"Open_IM/pkg/grpc-etcdv3/getcdv3"
 	"Open_IM/pkg/statistics"
 	"fmt"
 )
 
 var (
+	watcher      *getcdv3.Watcher
 	rpcServer    RPCServer
 	pushCh       PushConsumerHandler
 	pushTerminal []int32
@@ -23,7 +25,7 @@ var (
 )
 
 func Init(rpcPort int) {
-
+	watcher = getcdv3.NewWatcher()
 	rpcServer.Init(rpcPort)
 	pushCh.Init()
 	pushTerminal = []int32{constant.IOSPlatformID, constant.AndroidPlatformID}

internal/push/logic/push_to_client.go

@@ -13,13 +13,11 @@ import (
 	"Open_IM/pkg/common/config"
 	"Open_IM/pkg/common/constant"
 	"Open_IM/pkg/common/log"
-	"Open_IM/pkg/grpc-etcdv3/getcdv3"
 	pbPush "Open_IM/pkg/proto/push"
 	pbRelay "Open_IM/pkg/proto/relay"
 	"Open_IM/pkg/utils"
 	"context"
 	"encoding/json"
-	"strings"
 )
 
 type OpenIMContent struct {
@@ -38,7 +36,8 @@ func MsgToUser(pushMsg *pbPush.PushMsgReq) {
 	var wsResult []*pbRelay.SingleMsgToUser
 	isOfflinePush := utils.GetSwitchFromOptions(pushMsg.MsgData.Options, constant.IsOfflinePush)
 	log.Debug("Get msg from msg_transfer And push msg", pushMsg.OperationID, "PushData", pushMsg.String())
-	grpcCons := getcdv3.GetConn4Unique(config.Config.Etcd.EtcdSchema, strings.Join(config.Config.Etcd.EtcdAddr, ","), config.Config.RpcRegisterName.OpenImOnlineMessageRelayName)
+	//grpcCons := getcdv3.GetConn4Unique(config.Config.Etcd.EtcdSchema, strings.Join(config.Config.Etcd.EtcdAddr, ","), config.Config.RpcRegisterName.OpenImOnlineMessageRelayName)
+	grpcCons := watcher.GetAllConns()
 	//Online push message
 	log.Debug("test", pushMsg.OperationID, "len  grpc", len(grpcCons), "data", pushMsg.String())
 	for _, v := range grpcCons {

pkg/grpc-etcdv3/getcdv3/watcher.go

@@ -0,0 +1,170 @@
+package getcdv3
+
+import (
+	cfg "Open_IM/pkg/common/config"
+	"context"
+	"go.etcd.io/etcd/api/v3/mvccpb"
+	clientv3 "go.etcd.io/etcd/client/v3"
+	"google.golang.org/grpc"
+	"strings"
+	"sync"
+	"time"
+)
+
+type Watcher struct {
+	rwLock     sync.RWMutex
+	client     *clientv3.Client
+	kv         clientv3.KV
+	watcher    clientv3.Watcher
+	catalog    string
+	kvs        map[string]string
+	allService []string
+	schema     string
+	address    []string
+}
+
+func NewWatcher() (w *Watcher) {
+	var (
+		catalog string
+		config  clientv3.Config
+		client  *clientv3.Client
+		kv      clientv3.KV
+		watcher clientv3.Watcher
+		err     error
+	)
+	catalog = cfg.Config.Etcd.EtcdSchema + ":///" + cfg.Config.RpcRegisterName.OpenImOnlineMessageRelayName
+
+	config = clientv3.Config{
+		Endpoints:   cfg.Config.Etcd.EtcdAddr,               // 集群地址
+		DialTimeout: time.Duration(5000) * time.Millisecond, // 连接超时
+	}
+	// 1、建立连接
+	if client, err = clientv3.New(config); err != nil {
+		panic(err.Error())
+		return
+	}
+	// 2、得到KV和观察者
+	kv = clientv3.NewKV(client)
+	watcher = clientv3.NewWatcher(client)
+
+	w = &Watcher{
+		client:     client,
+		kv:         kv,
+		watcher:    watcher,
+		catalog:    catalog,
+		kvs:        make(map[string]string),
+		allService: make([]string, 0),
+		schema:     cfg.Config.Etcd.EtcdSchema,
+		address:    cfg.Config.Etcd.EtcdAddr,
+	}
+	return
+}
+
+// 监听变化
+func (w *Watcher) Run() (err error) {
+	var (
+		resp               *clientv3.GetResponse
+		kvpair             *mvccpb.KeyValue
+		watchStartRevision int64
+		watchChan          clientv3.WatchChan
+		watchResp          clientv3.WatchResponse
+		watchEvent         *clientv3.Event
+		key                string
+		value              string
+	)
+
+	// 1、get目录下的所有键值对，并且获知当前集群的revision
+	if resp, err = w.kv.Get(context.TODO(), w.catalog, clientv3.WithPrefix()); err != nil {
+		return
+	}
+	for _, kvpair = range resp.Kvs {
+		key = string(kvpair.Key)
+		value = string(kvpair.Value)
+		w.kvs[key] = value
+	}
+	w.updateServices()
+
+	// 2、从该revision向后监听变化事件
+	go func() {
+		// 从GET时刻的后续版本开始监听变化
+		watchStartRevision = resp.Header.Revision + 1
+		// 监听目录的后续变化
+		watchChan = w.watcher.Watch(context.TODO(), w.catalog, clientv3.WithRev(watchStartRevision), clientv3.WithPrefix())
+		// 处理监听事件
+		for watchResp = range watchChan {
+			for _, watchEvent = range watchResp.Events {
+				switch watchEvent.Type {
+				case mvccpb.PUT: // 任务保存事件
+					w.rwLock.Lock()
+
+					key = string(watchEvent.Kv.Key)
+					value = string(watchEvent.Kv.Value)
+					w.kvs[key] = value
+					w.updateServices()
+
+					w.rwLock.Unlock()
+				case mvccpb.DELETE: // 任务被删除了
+					w.rwLock.Lock()
+
+					key = string(watchEvent.Kv.Key)
+					delete(w.kvs, key)
+					w.updateServices()
+
+					w.rwLock.Unlock()
+				}
+			}
+		}
+	}()
+	return
+}
+
+func (w *Watcher) updateServices() {
+	var (
+		maps        map[string]string
+		key         string
+		serviceName string
+	)
+	w.allService = make([]string, 0)
+	maps = make(map[string]string)
+	for key, _ = range w.kvs {
+		serviceName = getServiceName(key)
+		if _, ok := maps[serviceName]; ok == true {
+			continue
+		}
+		maps[serviceName] = serviceName
+		w.allService = append(w.allService, serviceName)
+	}
+}
+
+func getServiceName(key string) (name string) {
+	var (
+		index int
+		str   string
+	)
+	index = strings.LastIndex(key, "///")
+	str = key[index+len("///"):]
+	index = strings.Index(str, "/")
+	name = str[:index]
+	return
+}
+
+func (w *Watcher) GetAllConns() (conns []*grpc.ClientConn) {
+	var (
+		services   []string
+		service    string
+		clientConn *grpc.ClientConn
+	)
+	w.rwLock.RLock()
+	services = w.allService
+	w.rwLock.RUnlock()
+
+	conns = make([]*grpc.ClientConn, 0)
+	for _, service = range services {
+		clientConn = GetConn(w.schema, strings.Join(w.address, ","), service)
+		if clientConn == nil {
+			continue
+		}
+		conns = append(conns, clientConn)
+	}
+	return
+}