159 lines
4 KiB
Go
159 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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