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stopper.go
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stopper.go
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// Copyright 2016 CoreOS, 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 stop
import (
"sync"
)
var AlreadyDone <-chan struct{}
func init() {
closeMe := make(chan struct{})
close(closeMe)
AlreadyDone = closeMe
}
type Stoppable interface {
Stop() <-chan struct{}
}
type Group struct {
stoppables []StopperFunc
stoppablesLock sync.Mutex
}
type StopperFunc func() <-chan struct{}
func NewGroup() *Group {
return &Group{
stoppables: make([]StopperFunc, 0),
}
}
func (cg *Group) Add(toAdd Stoppable) {
cg.stoppablesLock.Lock()
defer cg.stoppablesLock.Unlock()
cg.stoppables = append(cg.stoppables, toAdd.Stop)
}
func (cg *Group) AddFunc(toAddFunc StopperFunc) {
cg.stoppablesLock.Lock()
defer cg.stoppablesLock.Unlock()
cg.stoppables = append(cg.stoppables, toAddFunc)
}
func (cg *Group) Stop() <-chan struct{} {
cg.stoppablesLock.Lock()
defer cg.stoppablesLock.Unlock()
whenDone := make(chan struct{})
waitChannels := make([]<-chan struct{}, 0, len(cg.stoppables))
for _, toStop := range cg.stoppables {
waitFor := toStop()
if waitFor == nil {
panic("Someone returned a nil chan from Stop")
}
waitChannels = append(waitChannels, waitFor)
}
cg.stoppables = make([]StopperFunc, 0)
go func() {
for _, waitForMe := range waitChannels {
<-waitForMe
}
close(whenDone)
}()
return whenDone
}