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