+++ /dev/null
-/*
- *
- * 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 resolver defines APIs for name resolution in gRPC.
-// All APIs in this package are experimental.
-package resolver
-
-var (
- // m is a map from scheme to resolver builder.
- m = make(map[string]Builder)
- // defaultScheme is the default scheme to use.
- defaultScheme = "passthrough"
-)
-
-// TODO(bar) install dns resolver in init(){}.
-
-// Register registers the resolver builder to the resolver map.
-// b.Scheme will be used as the scheme registered with this builder.
-func Register(b Builder) {
- m[b.Scheme()] = b
-}
-
-// Get returns the resolver builder registered with the given scheme.
-// If no builder is register with the scheme, the default scheme will
-// be used.
-// If the default scheme is not modified, "dns" will be the default
-// scheme, and the preinstalled dns resolver will be used.
-// If the default scheme is modified, and a resolver is registered with
-// the scheme, that resolver will be returned.
-// If the default scheme is modified, and no resolver is registered with
-// the scheme, nil will be returned.
-func Get(scheme string) Builder {
- if b, ok := m[scheme]; ok {
- return b
- }
- if b, ok := m[defaultScheme]; ok {
- return b
- }
- return nil
-}
-
-// SetDefaultScheme sets the default scheme that will be used.
-// The default default scheme is "dns".
-func SetDefaultScheme(scheme string) {
- defaultScheme = scheme
-}
-
-// AddressType indicates the address type returned by name resolution.
-type AddressType uint8
-
-const (
- // Backend indicates the address is for a backend server.
- Backend AddressType = iota
- // GRPCLB indicates the address is for a grpclb load balancer.
- GRPCLB
-)
-
-// Address represents a server the client connects to.
-// This is the EXPERIMENTAL API and may be changed or extended in the future.
-type Address struct {
- // Addr is the server address on which a connection will be established.
- Addr string
- // Type is the type of this address.
- Type AddressType
- // ServerName is the name of this address.
- // It's the name of the grpc load balancer, which will be used for authentication.
- ServerName string
- // Metadata is the information associated with Addr, which may be used
- // to make load balancing decision.
- Metadata interface{}
-}
-
-// BuildOption includes additional information for the builder to create
-// the resolver.
-type BuildOption struct {
-}
-
-// ClientConn contains the callbacks for resolver to notify any updates
-// to the gRPC ClientConn.
-type ClientConn interface {
- // NewAddress is called by resolver to notify ClientConn a new list
- // of resolved addresses.
- // The address list should be the complete list of resolved addresses.
- NewAddress(addresses []Address)
- // NewServiceConfig is called by resolver to notify ClientConn a new
- // service config. The service config should be provided as a json string.
- NewServiceConfig(serviceConfig string)
-}
-
-// Target represents a target for gRPC, as specified in:
-// https://github.com/grpc/grpc/blob/master/doc/naming.md.
-type Target struct {
- Scheme string
- Authority string
- Endpoint string
-}
-
-// Builder creates a resolver that will be used to watch name resolution updates.
-type Builder interface {
- // Build creates a new resolver for the given target.
- //
- // gRPC dial calls Build synchronously, and fails if the returned error is
- // not nil.
- Build(target Target, cc ClientConn, opts BuildOption) (Resolver, error)
- // Scheme returns the scheme supported by this resolver.
- // Scheme is defined at https://github.com/grpc/grpc/blob/master/doc/naming.md.
- Scheme() string
-}
-
-// ResolveNowOption includes additional information for ResolveNow.
-type ResolveNowOption struct{}
-
-// Resolver watches for the updates on the specified target.
-// Updates include address updates and service config updates.
-type Resolver interface {
- // ResolveNow will be called by gRPC to try to resolve the target name again.
- // It's just a hint, resolver can ignore this if it's not necessary.
- ResolveNow(ResolveNowOption)
- // Close closes the resolver.
- Close()
-}
-
-// UnregisterForTesting removes the resolver builder with the given scheme from the
-// resolver map.
-// This function is for testing only.
-func UnregisterForTesting(scheme string) {
- delete(m, scheme)
-}
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