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grpclb_remote_balancer.go 8.76 KB
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/*
*
* Copyright 2017 gRPC authors.
*
* Licensed 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 grpclb
import (
"fmt"
"io"
"net"
"reflect"
"time"
timestamppb "github.com/golang/protobuf/ptypes/timestamp"
"golang.org/x/net/context"
"google.golang.org/grpc"
"google.golang.org/grpc/balancer"
lbpb "google.golang.org/grpc/balancer/grpclb/grpc_lb_v1"
"google.golang.org/grpc/connectivity"
"google.golang.org/grpc/grpclog"
"google.golang.org/grpc/internal"
"google.golang.org/grpc/internal/channelz"
"google.golang.org/grpc/metadata"
"google.golang.org/grpc/resolver"
)
// processServerList updates balaner's internal state, create/remove SubConns
// and regenerates picker using the received serverList.
func (lb *lbBalancer) processServerList(l *lbpb.ServerList) {
grpclog.Infof("lbBalancer: processing server list: %+v", l)
lb.mu.Lock()
defer lb.mu.Unlock()
// Set serverListReceived to true so fallback will not take effect if it has
// not hit timeout.
lb.serverListReceived = true
// If the new server list == old server list, do nothing.
if reflect.DeepEqual(lb.fullServerList, l.Servers) {
grpclog.Infof("lbBalancer: new serverlist same as the previous one, ignoring")
return
}
lb.fullServerList = l.Servers
var backendAddrs []resolver.Address
for i, s := range l.Servers {
if s.Drop {
continue
}
md := metadata.Pairs(lbTokeyKey, s.LoadBalanceToken)
ip := net.IP(s.IpAddress)
ipStr := ip.String()
if ip.To4() == nil {
// Add square brackets to ipv6 addresses, otherwise net.Dial() and
// net.SplitHostPort() will return too many colons error.
ipStr = fmt.Sprintf("[%s]", ipStr)
}
addr := resolver.Address{
Addr: fmt.Sprintf("%s:%d", ipStr, s.Port),
Metadata: &md,
}
grpclog.Infof("lbBalancer: server list entry[%d]: ipStr:|%s|, port:|%d|, load balancer token:|%v|",
i, ipStr, s.Port, s.LoadBalanceToken)
backendAddrs = append(backendAddrs, addr)
}
// Call refreshSubConns to create/remove SubConns.
lb.refreshSubConns(backendAddrs)
// Regenerate and update picker no matter if there's update on backends (if
// any SubConn will be newed/removed). Because since the full serverList was
// different, there might be updates in drops or pick weights(different
// number of duplicates). We need to update picker with the fulllist.
//
// Now with cache, even if SubConn was newed/removed, there might be no
// state changes.
lb.regeneratePicker()
lb.cc.UpdateBalancerState(lb.state, lb.picker)
}
// refreshSubConns creates/removes SubConns with backendAddrs. It returns a bool
// indicating whether the backendAddrs are different from the cached
// backendAddrs (whether any SubConn was newed/removed).
// Caller must hold lb.mu.
func (lb *lbBalancer) refreshSubConns(backendAddrs []resolver.Address) bool {
lb.backendAddrs = nil
var backendsUpdated bool
// addrsSet is the set converted from backendAddrs, it's used to quick
// lookup for an address.
addrsSet := make(map[resolver.Address]struct{})
// Create new SubConns.
for _, addr := range backendAddrs {
addrWithoutMD := addr
addrWithoutMD.Metadata = nil
addrsSet[addrWithoutMD] = struct{}{}
lb.backendAddrs = append(lb.backendAddrs, addrWithoutMD)
if _, ok := lb.subConns[addrWithoutMD]; !ok {
backendsUpdated = true
// Use addrWithMD to create the SubConn.
sc, err := lb.cc.NewSubConn([]resolver.Address{addr}, balancer.NewSubConnOptions{})
if err != nil {
grpclog.Warningf("roundrobinBalancer: failed to create new SubConn: %v", err)
continue
}
lb.subConns[addrWithoutMD] = sc // Use the addr without MD as key for the map.
if _, ok := lb.scStates[sc]; !ok {
// Only set state of new sc to IDLE. The state could already be
// READY for cached SubConns.
lb.scStates[sc] = connectivity.Idle
}
sc.Connect()
}
}
for a, sc := range lb.subConns {
// a was removed by resolver.
if _, ok := addrsSet[a]; !ok {
backendsUpdated = true
lb.cc.RemoveSubConn(sc)
delete(lb.subConns, a)
// Keep the state of this sc in b.scStates until sc's state becomes Shutdown.
// The entry will be deleted in HandleSubConnStateChange.
}
}
return backendsUpdated
}
func (lb *lbBalancer) readServerList(s *balanceLoadClientStream) error {
for {
reply, err := s.Recv()
if err != nil {
if err == io.EOF {
return errServerTerminatedConnection
}
return fmt.Errorf("grpclb: failed to recv server list: %v", err)
}
if serverList := reply.GetServerList(); serverList != nil {
lb.processServerList(serverList)
}
}
}
func (lb *lbBalancer) sendLoadReport(s *balanceLoadClientStream, interval time.Duration) {
ticker := time.NewTicker(interval)
defer ticker.Stop()
for {
select {
case <-ticker.C:
case <-s.Context().Done():
return
}
stats := lb.clientStats.toClientStats()
t := time.Now()
stats.Timestamp = &timestamppb.Timestamp{
Seconds: t.Unix(),
Nanos: int32(t.Nanosecond()),
}
if err := s.Send(&lbpb.LoadBalanceRequest{
LoadBalanceRequestType: &lbpb.LoadBalanceRequest_ClientStats{
ClientStats: stats,
},
}); err != nil {
return
}
}
}
func (lb *lbBalancer) callRemoteBalancer() (backoff bool, _ error) {
lbClient := &loadBalancerClient{cc: lb.ccRemoteLB}
ctx, cancel := context.WithCancel(context.Background())
defer cancel()
stream, err := lbClient.BalanceLoad(ctx, grpc.FailFast(false))
if err != nil {
return true, fmt.Errorf("grpclb: failed to perform RPC to the remote balancer %v", err)
}
// grpclb handshake on the stream.
initReq := &lbpb.LoadBalanceRequest{
LoadBalanceRequestType: &lbpb.LoadBalanceRequest_InitialRequest{
InitialRequest: &lbpb.InitialLoadBalanceRequest{
Name: lb.target,
},
},
}
if err := stream.Send(initReq); err != nil {
return true, fmt.Errorf("grpclb: failed to send init request: %v", err)
}
reply, err := stream.Recv()
if err != nil {
return true, fmt.Errorf("grpclb: failed to recv init response: %v", err)
}
initResp := reply.GetInitialResponse()
if initResp == nil {
return true, fmt.Errorf("grpclb: reply from remote balancer did not include initial response")
}
if initResp.LoadBalancerDelegate != "" {
return true, fmt.Errorf("grpclb: Delegation is not supported")
}
go func() {
if d := convertDuration(initResp.ClientStatsReportInterval); d > 0 {
lb.sendLoadReport(stream, d)
}
}()
// No backoff if init req/resp handshake was successful.
return false, lb.readServerList(stream)
}
func (lb *lbBalancer) watchRemoteBalancer() {
var retryCount int
for {
doBackoff, err := lb.callRemoteBalancer()
select {
case <-lb.doneCh:
return
default:
if err != nil {
if err == errServerTerminatedConnection {
grpclog.Info(err)
} else {
grpclog.Error(err)
}
}
}
if !doBackoff {
retryCount = 0
continue
}
timer := time.NewTimer(lb.backoff.Backoff(retryCount))
select {
case <-timer.C:
case <-lb.doneCh:
timer.Stop()
return
}
retryCount++
}
}
func (lb *lbBalancer) dialRemoteLB(remoteLBName string) {
var dopts []grpc.DialOption
if creds := lb.opt.DialCreds; creds != nil {
if err := creds.OverrideServerName(remoteLBName); err == nil {
dopts = append(dopts, grpc.WithTransportCredentials(creds))
} else {
grpclog.Warningf("grpclb: failed to override the server name in the credentials: %v, using Insecure", err)
dopts = append(dopts, grpc.WithInsecure())
}
} else {
dopts = append(dopts, grpc.WithInsecure())
}
if lb.opt.Dialer != nil {
// WithDialer takes a different type of function, so we instead use a
// special DialOption here.
wcd := internal.WithContextDialer.(func(func(context.Context, string) (net.Conn, error)) grpc.DialOption)
dopts = append(dopts, wcd(lb.opt.Dialer))
}
// Explicitly set pickfirst as the balancer.
dopts = append(dopts, grpc.WithBalancerName(grpc.PickFirstBalancerName))
wrb := internal.WithResolverBuilder.(func(resolver.Builder) grpc.DialOption)
dopts = append(dopts, wrb(lb.manualResolver))
if channelz.IsOn() {
dopts = append(dopts, grpc.WithChannelzParentID(lb.opt.ChannelzParentID))
}
// DialContext using manualResolver.Scheme, which is a random scheme generated
// when init grpclb. The target name is not important.
cc, err := grpc.DialContext(context.Background(), "grpclb:///grpclb.server", dopts...)
if err != nil {
grpclog.Fatalf("failed to dial: %v", err)
}
lb.ccRemoteLB = cc
go lb.watchRemoteBalancer()
}

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