62 lines
1.9 KiB
Go
62 lines
1.9 KiB
Go
// Copyright 2016 Google LLC
|
|
//
|
|
// 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 internal
|
|
|
|
import (
|
|
"errors"
|
|
|
|
"google.golang.org/grpc/naming"
|
|
)
|
|
|
|
// PoolResolver provides a fixed list of addresses to load balance between
|
|
// and does not provide further updates.
|
|
type PoolResolver struct {
|
|
poolSize int
|
|
dialOpt *DialSettings
|
|
ch chan []*naming.Update
|
|
}
|
|
|
|
// NewPoolResolver returns a PoolResolver
|
|
// This is an EXPERIMENTAL API and may be changed or removed in the future.
|
|
func NewPoolResolver(size int, o *DialSettings) *PoolResolver {
|
|
return &PoolResolver{poolSize: size, dialOpt: o}
|
|
}
|
|
|
|
// Resolve returns a Watcher for the endpoint defined by the DialSettings
|
|
// provided to NewPoolResolver.
|
|
func (r *PoolResolver) Resolve(target string) (naming.Watcher, error) {
|
|
if r.dialOpt.Endpoint == "" {
|
|
return nil, errors.New("no endpoint configured")
|
|
}
|
|
addrs := make([]*naming.Update, 0, r.poolSize)
|
|
for i := 0; i < r.poolSize; i++ {
|
|
addrs = append(addrs, &naming.Update{Op: naming.Add, Addr: r.dialOpt.Endpoint, Metadata: i})
|
|
}
|
|
r.ch = make(chan []*naming.Update, 1)
|
|
r.ch <- addrs
|
|
return r, nil
|
|
}
|
|
|
|
// Next returns a static list of updates on the first call,
|
|
// and blocks indefinitely until Close is called on subsequent calls.
|
|
func (r *PoolResolver) Next() ([]*naming.Update, error) {
|
|
return <-r.ch, nil
|
|
}
|
|
|
|
// Close releases resources associated with the pool and causes Next to unblock.
|
|
func (r *PoolResolver) Close() {
|
|
close(r.ch)
|
|
}
|