84 lines
2.2 KiB
Go
84 lines
2.2 KiB
Go
/*
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Copyright 2014 Google Inc. 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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"time"
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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
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// wait channel is closed. Will always poll at least once.
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func Poll(interval time.Duration, cycles int, condition ConditionFunc) error {
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return WaitFor(poller(interval, cycles), 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 implements the looping for a wait.
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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 at most cycles * interval has elapsed and then
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// close the channel. Over very short intervals you may receive
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// no ticks before being closed.
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func poller(interval time.Duration, cycles int) 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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after := time.After(interval * time.Duration(cycles))
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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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