With CoreDNS now supporting etcdv3 as the DNS backend, we can update our federation target to etcdv3. Users will now be able to use etcdv3 server as the federation backbone. Minio will update bucket data to etcdv3 and CoreDNS can pick that data up and serve it as bucket style DNS path.
158 lines
4 KiB
Go
158 lines
4 KiB
Go
/*
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*
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* Copyright 2017 gRPC authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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*/
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package grpc
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import (
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"fmt"
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"strings"
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"google.golang.org/grpc/grpclog"
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"google.golang.org/grpc/resolver"
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)
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// ccResolverWrapper is a wrapper on top of cc for resolvers.
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// It implements resolver.ClientConnection interface.
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type ccResolverWrapper struct {
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cc *ClientConn
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resolver resolver.Resolver
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addrCh chan []resolver.Address
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scCh chan string
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done chan struct{}
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}
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// split2 returns the values from strings.SplitN(s, sep, 2).
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// If sep is not found, it returns ("", s, false) instead.
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func split2(s, sep string) (string, string, bool) {
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spl := strings.SplitN(s, sep, 2)
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if len(spl) < 2 {
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return "", "", false
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}
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return spl[0], spl[1], true
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}
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// parseTarget splits target into a struct containing scheme, authority and
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// endpoint.
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//
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// If target is not a valid scheme://authority/endpoint, it returns {Endpoint:
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// target}.
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func parseTarget(target string) (ret resolver.Target) {
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var ok bool
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ret.Scheme, ret.Endpoint, ok = split2(target, "://")
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if !ok {
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return resolver.Target{Endpoint: target}
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}
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ret.Authority, ret.Endpoint, ok = split2(ret.Endpoint, "/")
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if !ok {
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return resolver.Target{Endpoint: target}
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}
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return ret
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}
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// newCCResolverWrapper parses cc.target for scheme and gets the resolver
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// builder for this scheme and builds the resolver. The monitoring goroutine
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// for it is not started yet and can be created by calling start().
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//
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// If withResolverBuilder dial option is set, the specified resolver will be
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// used instead.
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func newCCResolverWrapper(cc *ClientConn) (*ccResolverWrapper, error) {
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rb := cc.dopts.resolverBuilder
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if rb == nil {
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return nil, fmt.Errorf("could not get resolver for scheme: %q", cc.parsedTarget.Scheme)
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}
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ccr := &ccResolverWrapper{
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cc: cc,
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addrCh: make(chan []resolver.Address, 1),
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scCh: make(chan string, 1),
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done: make(chan struct{}),
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}
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var err error
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ccr.resolver, err = rb.Build(cc.parsedTarget, ccr, resolver.BuildOption{DisableServiceConfig: cc.dopts.disableServiceConfig})
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if err != nil {
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return nil, err
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}
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return ccr, nil
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}
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func (ccr *ccResolverWrapper) start() {
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go ccr.watcher()
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}
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// watcher processes address updates and service config updates sequentially.
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// Otherwise, we need to resolve possible races between address and service
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// config (e.g. they specify different balancer types).
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func (ccr *ccResolverWrapper) watcher() {
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for {
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select {
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case <-ccr.done:
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return
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default:
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}
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select {
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case addrs := <-ccr.addrCh:
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select {
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case <-ccr.done:
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return
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default:
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}
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grpclog.Infof("ccResolverWrapper: sending new addresses to cc: %v", addrs)
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ccr.cc.handleResolvedAddrs(addrs, nil)
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case sc := <-ccr.scCh:
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select {
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case <-ccr.done:
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return
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default:
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}
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grpclog.Infof("ccResolverWrapper: got new service config: %v", sc)
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ccr.cc.handleServiceConfig(sc)
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case <-ccr.done:
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return
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}
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}
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}
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func (ccr *ccResolverWrapper) resolveNow(o resolver.ResolveNowOption) {
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ccr.resolver.ResolveNow(o)
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}
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func (ccr *ccResolverWrapper) close() {
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ccr.resolver.Close()
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close(ccr.done)
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}
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// NewAddress is called by the resolver implemenetion to send addresses to gRPC.
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func (ccr *ccResolverWrapper) NewAddress(addrs []resolver.Address) {
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select {
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case <-ccr.addrCh:
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default:
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}
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ccr.addrCh <- addrs
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}
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// NewServiceConfig is called by the resolver implemenetion to send service
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// configs to gRPC.
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func (ccr *ccResolverWrapper) NewServiceConfig(sc string) {
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select {
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case <-ccr.scCh:
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default:
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}
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ccr.scCh <- sc
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}
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