mirror of https://github.com/k3s-io/k3s
114 lines
3.6 KiB
Go
114 lines
3.6 KiB
Go
/*
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Copyright 2014 The Kubernetes Authors All rights reserved.
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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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http://www.apache.org/licenses/LICENSE-2.0
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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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*/
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package wait
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import (
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"errors"
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"math/rand"
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"time"
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)
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// Jitter returns a time.Duration between duration and duration + maxFactor * duration,
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// to allow clients to avoid converging on periodic behavior. If maxFactor is 0.0, a
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// suggested default value will be chosen.
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func Jitter(duration time.Duration, maxFactor float64) time.Duration {
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if maxFactor <= 0.0 {
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maxFactor = 1.0
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}
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wait := duration + time.Duration(rand.Float64()*maxFactor*float64(duration))
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return wait
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}
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// ErrWaitTimeout is returned when the condition exited without success
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var ErrWaitTimeout = errors.New("timed out waiting for the condition")
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// ConditionFunc returns true if the condition is satisfied, or an error
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// if the loop should be aborted.
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type ConditionFunc func() (done bool, err error)
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// Poll tries a condition func until it returns true, an error, or the timeout
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// is reached. condition will always be invoked at least once but some intervals
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// may be missed if the condition takes too long or the time window is too short.
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// If you pass maxTimes = 0, Poll will loop until condition returns true or an
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// error.
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// Poll always waits the interval before the first check of the condition.
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// TODO: create a separate PollImmediate function that does not wait.
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func Poll(interval, timeout time.Duration, condition ConditionFunc) error {
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return WaitFor(poller(interval, timeout), condition)
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}
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// WaitFunc creates a channel that receives an item every time a test
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// should be executed and is closed when the last test should be invoked.
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type WaitFunc func() <-chan struct{}
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// WaitFor gets a channel from wait(), and then invokes c once for every value
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// placed on the channel and once more when the channel is closed. If c
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// returns an error the loop ends and that error is returned, and if c returns
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// true the loop ends and nil is returned. ErrWaitTimeout will be returned if
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// the channel is closed without c ever returning true.
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func WaitFor(wait WaitFunc, c ConditionFunc) error {
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w := wait()
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for {
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_, open := <-w
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ok, err := c()
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if err != nil {
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return err
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}
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if ok {
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return nil
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}
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if !open {
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break
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}
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}
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return ErrWaitTimeout
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}
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// poller returns a WaitFunc that will send to the channel every
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// interval until timeout has elapsed and then close the channel.
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// Over very short intervals you may receive no ticks before
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// the channel is closed closed. If maxTimes is 0, the channel
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// will never be closed.
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func poller(interval, timeout time.Duration) WaitFunc {
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return WaitFunc(func() <-chan struct{} {
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ch := make(chan struct{})
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go func() {
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tick := time.NewTicker(interval)
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defer tick.Stop()
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var after <-chan time.Time
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if timeout != 0 {
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// time.After is more convenient, but it
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// potentially leaves timers around much longer
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// than necessary if we exit early.
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timer := time.NewTimer(timeout)
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after = timer.C
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defer timer.Stop()
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}
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for {
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select {
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case <-tick.C:
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ch <- struct{}{}
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case <-after:
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close(ch)
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return
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}
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}
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}()
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return ch
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})
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}
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