Open-IM-Server/pkg/discoveryregistry/zookeeper/discover.go

package zookeeper

import (
	"context"
	"fmt"
	"strings"
	"sync"

	"github.com/OpenIMSDK/Open-IM-Server/pkg/common/log"
	"github.com/pkg/errors"

	"github.com/go-zookeeper/zk"
	"google.golang.org/grpc"
	"google.golang.org/grpc/resolver"
)

var ErrConnIsNil = errors.New("conn is nil")
var ErrConnIsNilButLocalNotNil = errors.New("conn is nil, but local is not nil")

func (s *ZkClient) watch(wg *sync.WaitGroup) {
	wg.Done()
	for {
		event := <-s.eventChan
		switch event.Type {
		case zk.EventSession:
		case zk.EventNodeCreated:
		case zk.EventNodeChildrenChanged:
			log.ZDebug(context.Background(), "zk event", "event", event.Path)
			l := strings.Split(event.Path, "/")
			s.lock.Lock()
			if len(l) > 1 {
				rpcName := l[len(l)-1]
				s.flushResolver(rpcName)
				if len(s.localConns[rpcName]) != 0 {
					delete(s.localConns, rpcName)
				}
			}
			s.lock.Unlock()
		case zk.EventNodeDataChanged:
		case zk.EventNodeDeleted:
		case zk.EventNotWatching:
		}
	}

}

func (s *ZkClient) GetConnsRemote(serviceName string) (conns []resolver.Address, err error) {
	path := s.getPath(serviceName)
	childNodes, _, err := s.conn.Children(path)
	if err != nil {
		return nil, errors.Wrap(err, "get children error")
	}
	for _, child := range childNodes {
		fullPath := path + "/" + child
		data, _, err := s.conn.Get(fullPath)
		if err != nil {
			if err == zk.ErrNoNode {
				return nil, errors.Wrap(err, "this is zk ErrNoNode")
			}
			return nil, errors.Wrap(err, "get children error")
		}
		conns = append(conns, resolver.Address{Addr: string(data), ServerName: serviceName})
	}
	_, _, _, err = s.conn.ChildrenW(s.getPath(serviceName))
	if err != nil {
		return nil, errors.Wrap(err, "children watch error")
	}
	if len(conns) == 0 {
		return nil, fmt.Errorf("no conn for service %s, grpc server may not exist, local conn is %v, please check zookeeper server %v, path: %s", serviceName, s.localConns, s.zkServers, s.zkRoot)
	}
	return conns, nil
}

func (s *ZkClient) GetConns(ctx context.Context, serviceName string, opts ...grpc.DialOption) ([]*grpc.ClientConn, error) {
	s.lock.Lock()
	opts = append(s.options, opts...)
	conns := s.localConns[serviceName]
	if len(conns) == 0 {
		var err error
		conns, err = s.GetConnsRemote(serviceName)
		if err != nil {
			return nil, err
		}
		s.localConns[serviceName] = conns
	}
	s.lock.Unlock()
	var ret []*grpc.ClientConn
	for _, conn := range conns {
		c, err := grpc.DialContext(ctx, conn.Addr, append(s.options, opts...)...)
		if err != nil {
			return nil, errors.Wrap(err, fmt.Sprintf("conns dialContext error, conn: %s", conn.Addr))
		}
		ret = append(ret, c)
	}
	return ret, nil
}

//	func (s *ZkClient) GetConn(ctx context.Context, serviceName string, opts ...grpc.DialOption) (*grpc.ClientConn, error) {
//		newOpts := append(s.options, grpc.WithDefaultServiceConfig(fmt.Sprintf(`{"LoadBalancingPolicy": "%s"}`, s.balancerName)))
//		return grpc.DialContext(ctx, fmt.Sprintf("%s:///%s", s.scheme, serviceName), append(newOpts, opts...)...)
//	}
func (s *ZkClient) GetConn(ctx context.Context, serviceName string, opts ...grpc.DialOption) (*grpc.ClientConn, error) {
	conns, err := s.GetConns(ctx, serviceName, opts...)
	if err != nil {
		return nil, err
	}
	if len(conns) == 0 {
		return nil, ErrConnIsNil
	}
	return s.getConnBalance(conns)
}

func (s *ZkClient) GetFirstConn(ctx context.Context, serviceName string, opts ...grpc.DialOption) (*grpc.ClientConn, error) {
	conns, err := s.GetConns(ctx, serviceName, opts...)
	if err != nil {
		return nil, err
	}
	if len(conns) == 0 {
		return nil, ErrConnIsNil
	}
	return conns[0], nil
}