mirror of https://github.com/status-im/consul.git
88 lines
2.7 KiB
Go
88 lines
2.7 KiB
Go
|
/*
|
||
|
|
Copyright 2016 The Kubernetes Authors.
|
||
|
|
|
||
|
|
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 watch
|
||
|
|
|
||
|
|
import (
|
||
|
|
"errors"
|
||
|
|
"time"
|
||
|
|
|
||
|
|
"k8s.io/apimachinery/pkg/util/wait"
|
||
|
|
)
|
||
|
|
|
||
|
|
// ConditionFunc returns true if the condition has been reached, false if it has not been reached yet,
|
||
|
|
// or an error if the condition cannot be checked and should terminate. In general, it is better to define
|
||
|
|
// level driven conditions over edge driven conditions (pod has ready=true, vs pod modified and ready changed
|
||
|
|
// from false to true).
|
||
|
|
type ConditionFunc func(event Event) (bool, error)
|
||
|
|
|
||
|
|
// ErrWatchClosed is returned when the watch channel is closed before timeout in Until.
|
||
|
|
var ErrWatchClosed = errors.New("watch closed before Until timeout")
|
||
|
|
|
||
|
|
// Until reads items from the watch until each provided condition succeeds, and then returns the last watch
|
||
|
|
// encountered. The first condition that returns an error terminates the watch (and the event is also returned).
|
||
|
|
// If no event has been received, the returned event will be nil.
|
||
|
|
// Conditions are satisfied sequentially so as to provide a useful primitive for higher level composition.
|
||
|
|
// A zero timeout means to wait forever.
|
||
|
|
func Until(timeout time.Duration, watcher Interface, conditions ...ConditionFunc) (*Event, error) {
|
||
|
|
ch := watcher.ResultChan()
|
||
|
|
defer watcher.Stop()
|
||
|
|
var after <-chan time.Time
|
||
|
|
if timeout > 0 {
|
||
|
|
after = time.After(timeout)
|
||
|
|
} else {
|
||
|
|
ch := make(chan time.Time)
|
||
|
|
defer close(ch)
|
||
|
|
after = ch
|
||
|
|
}
|
||
|
|
var lastEvent *Event
|
||
|
|
for _, condition := range conditions {
|
||
|
|
// check the next condition against the previous event and short circuit waiting for the next watch
|
||
|
|
if lastEvent != nil {
|
||
|
|
done, err := condition(*lastEvent)
|
||
|
|
if err != nil {
|
||
|
|
return lastEvent, err
|
||
|
|
}
|
||
|
|
if done {
|
||
|
|
continue
|
||
|
|
}
|
||
|
|
}
|
||
|
|
ConditionSucceeded:
|
||
|
|
for {
|
||
|
|
select {
|
||
|
|
case event, ok := <-ch:
|
||
|
|
if !ok {
|
||
|
|
return lastEvent, ErrWatchClosed
|
||
|
|
}
|
||
|
|
lastEvent = &event
|
||
|
|
|
||
|
|
// TODO: check for watch expired error and retry watch from latest point?
|
||
|
|
done, err := condition(event)
|
||
|
|
if err != nil {
|
||
|
|
return lastEvent, err
|
||
|
|
}
|
||
|
|
if done {
|
||
|
|
break ConditionSucceeded
|
||
|
|
}
|
||
|
|
|
||
|
|
case <-after:
|
||
|
|
return lastEvent, wait.ErrWaitTimeout
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
return lastEvent, nil
|
||
|
|
}
|