mirror of
https://github.com/ceph/ceph-csi.git
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58 lines
1.5 KiB
Go
58 lines
1.5 KiB
Go
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/*
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Copyright 2017 The Kubernetes Authors.
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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 waitgroup
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import (
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"fmt"
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"sync"
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)
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// SafeWaitGroup must not be copied after first use.
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type SafeWaitGroup struct {
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wg sync.WaitGroup
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mu sync.RWMutex
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// wait indicate whether Wait is called, if true,
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// then any Add with positive delta will return error.
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wait bool
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}
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// Add adds delta, which may be negative, similar to sync.WaitGroup.
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// If Add with a positive delta happens after Wait, it will return error,
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// which prevent unsafe Add.
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func (wg *SafeWaitGroup) Add(delta int) error {
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wg.mu.RLock()
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defer wg.mu.RUnlock()
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if wg.wait && delta > 0 {
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return fmt.Errorf("add with postive delta after Wait is forbidden")
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}
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wg.wg.Add(delta)
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return nil
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}
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// Done decrements the WaitGroup counter.
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func (wg *SafeWaitGroup) Done() {
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wg.wg.Done()
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}
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// Wait blocks until the WaitGroup counter is zero.
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func (wg *SafeWaitGroup) Wait() {
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wg.mu.Lock()
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wg.wait = true
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wg.mu.Unlock()
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wg.wg.Wait()
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}
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