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// Copyright 2016 Google Inc. All Rights Reserved.
//
// 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
}
func (r *PoolResolver) Close() {
close(r.ch)
}
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