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// Copyright 2016 The etcd 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 grpcproxy
import (
"fmt"
"os"
"sync"
"github.com/coreos/etcd/clientv3"
"github.com/coreos/etcd/clientv3/naming"
pb "github.com/coreos/etcd/etcdserver/etcdserverpb"
"golang.org/x/net/context"
"golang.org/x/time/rate"
"google.golang.org/grpc"
gnaming "google.golang.org/grpc/naming"
)
// allow maximum 1 retry per second
const resolveRetryRate = 1
type clusterProxy struct {
clus clientv3.Cluster
ctx context.Context
gr *naming.GRPCResolver
// advertise client URL
advaddr string
prefix string
umu sync.RWMutex
umap map[string]gnaming.Update
}
// NewClusterProxy takes optional prefix to fetch grpc-proxy member endpoints.
// The returned channel is closed when there is grpc-proxy endpoint registered
// and the client's context is canceled so the 'register' loop returns.
func NewClusterProxy(c *clientv3.Client, advaddr string, prefix string) (pb.ClusterServer, <-chan struct{}) {
cp := &clusterProxy{
clus: c.Cluster,
ctx: c.Ctx(),
gr: &naming.GRPCResolver{Client: c},
advaddr: advaddr,
prefix: prefix,
umap: make(map[string]gnaming.Update),
}
donec := make(chan struct{})
if advaddr != "" && prefix != "" {
go func() {
defer close(donec)
cp.resolve(prefix)
}()
return cp, donec
}
close(donec)
return cp, donec
}
func (cp *clusterProxy) resolve(prefix string) {
rm := rate.NewLimiter(rate.Limit(resolveRetryRate), resolveRetryRate)
for rm.Wait(cp.ctx) == nil {
wa, err := cp.gr.Resolve(prefix)
if err != nil {
plog.Warningf("failed to resolve %q (%v)", prefix, err)
continue
}
cp.monitor(wa)
}
}
func (cp *clusterProxy) monitor(wa gnaming.Watcher) {
for cp.ctx.Err() == nil {
ups, err := wa.Next()
if err != nil {
plog.Warningf("clusterProxy watcher error (%v)", err)
if grpc.ErrorDesc(err) == naming.ErrWatcherClosed.Error() {
return
}
}
cp.umu.Lock()
for i := range ups {
switch ups[i].Op {
case gnaming.Add:
cp.umap[ups[i].Addr] = *ups[i]
case gnaming.Delete:
delete(cp.umap, ups[i].Addr)
}
}
cp.umu.Unlock()
}
}
func (cp *clusterProxy) MemberAdd(ctx context.Context, r *pb.MemberAddRequest) (*pb.MemberAddResponse, error) {
mresp, err := cp.clus.MemberAdd(ctx, r.PeerURLs)
if err != nil {
return nil, err
}
resp := (pb.MemberAddResponse)(*mresp)
return &resp, err
}
func (cp *clusterProxy) MemberRemove(ctx context.Context, r *pb.MemberRemoveRequest) (*pb.MemberRemoveResponse, error) {
mresp, err := cp.clus.MemberRemove(ctx, r.ID)
if err != nil {
return nil, err
}
resp := (pb.MemberRemoveResponse)(*mresp)
return &resp, err
}
func (cp *clusterProxy) MemberUpdate(ctx context.Context, r *pb.MemberUpdateRequest) (*pb.MemberUpdateResponse, error) {
mresp, err := cp.clus.MemberUpdate(ctx, r.ID, r.PeerURLs)
if err != nil {
return nil, err
}
resp := (pb.MemberUpdateResponse)(*mresp)
return &resp, err
}
func (cp *clusterProxy) membersFromUpdates() ([]*pb.Member, error) {
cp.umu.RLock()
defer cp.umu.RUnlock()
mbs := make([]*pb.Member, 0, len(cp.umap))
for addr, upt := range cp.umap {
m, err := decodeMeta(fmt.Sprint(upt.Metadata))
if err != nil {
return nil, err
}
mbs = append(mbs, &pb.Member{Name: m.Name, ClientURLs: []string{addr}})
}
return mbs, nil
}
// MemberList wraps member list API with following rules:
// - If 'advaddr' is not empty and 'prefix' is not empty, return registered member lists via resolver
// - If 'advaddr' is not empty and 'prefix' is not empty and registered grpc-proxy members haven't been fetched, return the 'advaddr'
// - If 'advaddr' is not empty and 'prefix' is empty, return 'advaddr' without forcing it to 'register'
// - If 'advaddr' is empty, forward to member list API
func (cp *clusterProxy) MemberList(ctx context.Context, r *pb.MemberListRequest) (*pb.MemberListResponse, error) {
if cp.advaddr != "" {
if cp.prefix != "" {
mbs, err := cp.membersFromUpdates()
if err != nil {
return nil, err
}
if len(mbs) > 0 {
return &pb.MemberListResponse{Members: mbs}, nil
}
}
// prefix is empty or no grpc-proxy members haven't been registered
hostname, _ := os.Hostname()
return &pb.MemberListResponse{Members: []*pb.Member{{Name: hostname, ClientURLs: []string{cp.advaddr}}}}, nil
}
mresp, err := cp.clus.MemberList(ctx)
if err != nil {
return nil, err
}
resp := (pb.MemberListResponse)(*mresp)
return &resp, err
}
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