dex/vendor/go.etcd.io/etcd/clientv3/balancer/resolver/endpoint/endpoint.go

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2020-01-31 15:02:00 +05:30
// Copyright 2018 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 endpoint resolves etcd entpoints using grpc targets of the form 'endpoint://<id>/<endpoint>'.
package endpoint
import (
"context"
"fmt"
"net"
"net/url"
"strings"
"sync"
"google.golang.org/grpc/resolver"
)
const scheme = "endpoint"
var (
targetPrefix = fmt.Sprintf("%s://", scheme)
bldr *builder
)
func init() {
bldr = &builder{
resolverGroups: make(map[string]*ResolverGroup),
}
resolver.Register(bldr)
}
type builder struct {
mu sync.RWMutex
resolverGroups map[string]*ResolverGroup
}
// NewResolverGroup creates a new ResolverGroup with the given id.
func NewResolverGroup(id string) (*ResolverGroup, error) {
return bldr.newResolverGroup(id)
}
// ResolverGroup keeps all endpoints of resolvers using a common endpoint://<id>/ target
// up-to-date.
type ResolverGroup struct {
mu sync.RWMutex
id string
endpoints []string
resolvers []*Resolver
}
func (e *ResolverGroup) addResolver(r *Resolver) {
e.mu.Lock()
addrs := epsToAddrs(e.endpoints...)
e.resolvers = append(e.resolvers, r)
e.mu.Unlock()
r.cc.NewAddress(addrs)
}
func (e *ResolverGroup) removeResolver(r *Resolver) {
e.mu.Lock()
for i, er := range e.resolvers {
if er == r {
e.resolvers = append(e.resolvers[:i], e.resolvers[i+1:]...)
break
}
}
e.mu.Unlock()
}
// SetEndpoints updates the endpoints for ResolverGroup. All registered resolver are updated
// immediately with the new endpoints.
func (e *ResolverGroup) SetEndpoints(endpoints []string) {
addrs := epsToAddrs(endpoints...)
e.mu.Lock()
e.endpoints = endpoints
for _, r := range e.resolvers {
r.cc.NewAddress(addrs)
}
e.mu.Unlock()
}
// Target constructs a endpoint target using the endpoint id of the ResolverGroup.
func (e *ResolverGroup) Target(endpoint string) string {
return Target(e.id, endpoint)
}
// Target constructs a endpoint resolver target.
func Target(id, endpoint string) string {
return fmt.Sprintf("%s://%s/%s", scheme, id, endpoint)
}
// IsTarget checks if a given target string in an endpoint resolver target.
func IsTarget(target string) bool {
return strings.HasPrefix(target, "endpoint://")
}
func (e *ResolverGroup) Close() {
bldr.close(e.id)
}
// Build creates or reuses an etcd resolver for the etcd cluster name identified by the authority part of the target.
func (b *builder) Build(target resolver.Target, cc resolver.ClientConn, opts resolver.BuildOption) (resolver.Resolver, error) {
if len(target.Authority) < 1 {
return nil, fmt.Errorf("'etcd' target scheme requires non-empty authority identifying etcd cluster being routed to")
}
id := target.Authority
es, err := b.getResolverGroup(id)
if err != nil {
return nil, fmt.Errorf("failed to build resolver: %v", err)
}
r := &Resolver{
endpointID: id,
cc: cc,
}
es.addResolver(r)
return r, nil
}
func (b *builder) newResolverGroup(id string) (*ResolverGroup, error) {
b.mu.RLock()
_, ok := b.resolverGroups[id]
b.mu.RUnlock()
if ok {
return nil, fmt.Errorf("Endpoint already exists for id: %s", id)
}
es := &ResolverGroup{id: id}
b.mu.Lock()
b.resolverGroups[id] = es
b.mu.Unlock()
return es, nil
}
func (b *builder) getResolverGroup(id string) (*ResolverGroup, error) {
b.mu.RLock()
es, ok := b.resolverGroups[id]
b.mu.RUnlock()
if !ok {
return nil, fmt.Errorf("ResolverGroup not found for id: %s", id)
}
return es, nil
}
func (b *builder) close(id string) {
b.mu.Lock()
delete(b.resolverGroups, id)
b.mu.Unlock()
}
func (b *builder) Scheme() string {
return scheme
}
// Resolver provides a resolver for a single etcd cluster, identified by name.
type Resolver struct {
endpointID string
cc resolver.ClientConn
sync.RWMutex
}
// TODO: use balancer.epsToAddrs
func epsToAddrs(eps ...string) (addrs []resolver.Address) {
addrs = make([]resolver.Address, 0, len(eps))
for _, ep := range eps {
addrs = append(addrs, resolver.Address{Addr: ep})
}
return addrs
}
func (*Resolver) ResolveNow(o resolver.ResolveNowOption) {}
func (r *Resolver) Close() {
es, err := bldr.getResolverGroup(r.endpointID)
if err != nil {
return
}
es.removeResolver(r)
}
// ParseEndpoint endpoint parses an endpoint of the form
// (http|https)://<host>*|(unix|unixs)://<path>)
// and returns a protocol ('tcp' or 'unix'),
// host (or filepath if a unix socket),
// scheme (http, https, unix, unixs).
func ParseEndpoint(endpoint string) (proto string, host string, scheme string) {
proto = "tcp"
host = endpoint
url, uerr := url.Parse(endpoint)
if uerr != nil || !strings.Contains(endpoint, "://") {
return proto, host, scheme
}
scheme = url.Scheme
// strip scheme:// prefix since grpc dials by host
host = url.Host
switch url.Scheme {
case "http", "https":
case "unix", "unixs":
proto = "unix"
host = url.Host + url.Path
default:
proto, host = "", ""
}
return proto, host, scheme
}
// ParseTarget parses a endpoint://<id>/<endpoint> string and returns the parsed id and endpoint.
// If the target is malformed, an error is returned.
func ParseTarget(target string) (string, string, error) {
noPrefix := strings.TrimPrefix(target, targetPrefix)
if noPrefix == target {
return "", "", fmt.Errorf("malformed target, %s prefix is required: %s", targetPrefix, target)
}
parts := strings.SplitN(noPrefix, "/", 2)
if len(parts) != 2 {
return "", "", fmt.Errorf("malformed target, expected %s://<id>/<endpoint>, but got %s", scheme, target)
}
return parts[0], parts[1], nil
}
// Dialer dials a endpoint using net.Dialer.
// Context cancelation and timeout are supported.
func Dialer(ctx context.Context, dialEp string) (net.Conn, error) {
proto, host, _ := ParseEndpoint(dialEp)
select {
case <-ctx.Done():
return nil, ctx.Err()
default:
}
dialer := &net.Dialer{}
if deadline, ok := ctx.Deadline(); ok {
dialer.Deadline = deadline
}
return dialer.DialContext(ctx, proto, host)
}