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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 grpc
import (
"fmt"
"strings"
"google.golang.org/grpc/grpclog"
"google.golang.org/grpc/internal/channelz"
"google.golang.org/grpc/resolver"
)
// ccResolverWrapper is a wrapper on top of cc for resolvers.
// It implements resolver.ClientConnection interface.
type ccResolverWrapper struct {
cc *ClientConn
resolver resolver.Resolver
addrCh chan []resolver.Address
scCh chan string
done chan struct{}
lastAddressesCount int
}
// split2 returns the values from strings.SplitN(s, sep, 2).
// If sep is not found, it returns ("", s, false) instead.
func split2(s, sep string) (string, string, bool) {
spl := strings.SplitN(s, sep, 2)
if len(spl) < 2 {
return "", "", false
}
return spl[0], spl[1], true
}
// parseTarget splits target into a struct containing scheme, authority and
// endpoint.
//
// If target is not a valid scheme://authority/endpoint, it returns {Endpoint:
// target}.
func parseTarget(target string) (ret resolver.Target) {
var ok bool
ret.Scheme, ret.Endpoint, ok = split2(target, "://")
if !ok {
return resolver.Target{Endpoint: target}
}
ret.Authority, ret.Endpoint, ok = split2(ret.Endpoint, "/")
if !ok {
return resolver.Target{Endpoint: target}
}
return ret
}
// newCCResolverWrapper parses cc.target for scheme and gets the resolver
// builder for this scheme and builds the resolver. The monitoring goroutine
// for it is not started yet and can be created by calling start().
//
// If withResolverBuilder dial option is set, the specified resolver will be
// used instead.
func newCCResolverWrapper(cc *ClientConn) (*ccResolverWrapper, error) {
rb := cc.dopts.resolverBuilder
if rb == nil {
return nil, fmt.Errorf("could not get resolver for scheme: %q", cc.parsedTarget.Scheme)
}
ccr := &ccResolverWrapper{
cc: cc,
addrCh: make(chan []resolver.Address, 1),
scCh: make(chan string, 1),
done: make(chan struct{}),
}
var err error
ccr.resolver, err = rb.Build(cc.parsedTarget, ccr, resolver.BuildOption{DisableServiceConfig: cc.dopts.disableServiceConfig})
if err != nil {
return nil, err
}
return ccr, nil
}
func (ccr *ccResolverWrapper) resolveNow(o resolver.ResolveNowOption) {
ccr.resolver.ResolveNow(o)
}
func (ccr *ccResolverWrapper) close() {
ccr.resolver.Close()
close(ccr.done)
}
// NewAddress is called by the resolver implemenetion to send addresses to gRPC.
func (ccr *ccResolverWrapper) NewAddress(addrs []resolver.Address) {
select {
case <-ccr.done:
return
default:
}
grpclog.Infof("ccResolverWrapper: sending new addresses to cc: %v", addrs)
if channelz.IsOn() {
ccr.addChannelzTraceEvent(addrs)
}
ccr.cc.handleResolvedAddrs(addrs, nil)
}
// NewServiceConfig is called by the resolver implemenetion to send service
// configs to gRPC.
func (ccr *ccResolverWrapper) NewServiceConfig(sc string) {
select {
case <-ccr.done:
return
default:
}
grpclog.Infof("ccResolverWrapper: got new service config: %v", sc)
ccr.cc.handleServiceConfig(sc)
}
func (ccr *ccResolverWrapper) addChannelzTraceEvent(addrs []resolver.Address) {
if len(addrs) == 0 && ccr.lastAddressesCount != 0 {
channelz.AddTraceEvent(ccr.cc.channelzID, &channelz.TraceEventDesc{
Desc: "Resolver returns an empty address list",
Severity: channelz.CtWarning,
})
} else if len(addrs) != 0 && ccr.lastAddressesCount == 0 {
var s string
for i, a := range addrs {
if a.ServerName != "" {
s += a.Addr + "(" + a.ServerName + ")"
} else {
s += a.Addr
}
if i != len(addrs)-1 {
s += " "
}
}
channelz.AddTraceEvent(ccr.cc.channelzID, &channelz.TraceEventDesc{
Desc: fmt.Sprintf("Resolver returns a non-empty address list (previous one was empty) %q", s),
Severity: channelz.CtINFO,
})
}
ccr.lastAddressesCount = len(addrs)
}