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notifier.go
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notifier.go
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// Copyright (c) 2019 The Jaeger Authors.
// Copyright (c) 2017 Uber Technologies, Inc.
//
// 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 discovery
import (
"sync"
)
// Notifier listens to a service discovery system and notifies registered
// observers of changes in the resource instances. A complete set of instances
// is always provided to the observers.
type Notifier interface {
Register(chan<- []string)
Unregister(chan<- []string)
}
// Dispatcher can register/unregister observers and pass notifications to them
type Dispatcher struct {
sync.Mutex
observers []chan<- []string
}
// Register adds an observer to the list.
func (d *Dispatcher) Register(ch chan<- []string) {
d.Unregister(ch)
d.Lock()
defer d.Unlock()
d.observers = append(d.observers, ch)
}
// Unregister removes an observer from the list.
func (d *Dispatcher) Unregister(ch chan<- []string) {
d.Lock()
defer d.Unlock()
for i := range d.observers {
if ch == d.observers[i] {
d.observers = append(d.observers[0:i], d.observers[i+1:]...)
break
}
}
}
// Notify sends instances to all Observers
func (d *Dispatcher) Notify(instances []string) {
d.Lock()
defer d.Unlock()
for i := range d.observers {
d.observers[i] <- instances
}
}