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resolver.go
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resolver.go
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package redis
import (
"errors"
"github.com/kenkinsai/denny/naming"
"google.golang.org/grpc/resolver"
"strings"
"time"
)
// NewResolver is alias to New(), and also register resolver automatically
// so client does not have to call register resolver everytime
func NewResolver(redisAddr, redisPwd, serviceName string) naming.Registry {
registry := New(redisAddr, redisPwd, serviceName)
resolver.Register(registry)
return registry
}
func (r *redis) Build(target resolver.Target, cc resolver.ClientConn, opts resolver.BuildOptions) (resolver.Resolver, error) {
if r.cli == nil {
return nil, errors.New("etcd client was not initialised")
}
r.cc = cc
r.WithFields(map[string]interface{}{
"scheme": target.Scheme,
"endpoint": target.Endpoint,
})
keyPrefix := "/" + target.Scheme + "/" + target.Endpoint + "/"
go r.watch(keyPrefix)
return r, nil
}
func (r *redis) watch(keyPrefix string) {
var (
addrList []resolver.Address
ticker = time.NewTicker(time.Duration(5) * time.Second)
)
list, err := r.addressList(keyPrefix, addrList)
if err != nil {
r.Errorf("cannot get address list: %v", err)
} else {
addrList = list[:]
}
r.cc.UpdateState(resolver.State{
Addresses: addrList,
})
for {
select {
case _ = <-ticker.C:
updatedList, err := r.addressList(keyPrefix, addrList)
if err != nil {
r.Errorf("cannot get address list: %v", err)
} else {
needUpdate := false
// append to state list if it's not exist
for _, addr := range updatedList {
if !naming.Exist(addrList, addr.Addr) {
needUpdate = true
addrList = append(addrList, addr)
}
}
// remove dead peer
for _, addr := range addrList {
if !naming.Exist(updatedList, addr.Addr) {
needUpdate = true
if s, ok := naming.Remove(addrList, addr.Addr); ok {
addrList = s
}
}
}
if needUpdate {
r.cc.UpdateState(resolver.State{Addresses: addrList})
}
}
}
}
}
func (r *redis) addressList(keyPrefix string, addrList []resolver.Address) ([]resolver.Address, error) {
resp, err := r.cli.Keys(keyPrefix + "*").Result()
if err != nil {
return nil, err
}
for _, key := range resp {
addrList = append(addrList, resolver.Address{Addr: strings.TrimPrefix(key, keyPrefix)})
}
return addrList, nil
}
func (r redis) Scheme() string {
return naming.Prefix
}
func (r redis) SvcName() string {
return r.Scheme() + ":///" + r.serviceName
}
func (r *redis) ResolveNow(resolver.ResolveNowOptions) {
// TODO
}
func (r *redis) Close() {
_ = r.cli.Close()
}