mirror of https://github.com/pulumi/pulumi.git
72 lines
1.6 KiB
Go
72 lines
1.6 KiB
Go
// Copyright 2016-2023, Pulumi Corporation.
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//
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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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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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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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package internal
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import (
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"fmt"
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"sync"
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)
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// WorkGroup mimicks the interface of `sync.WaitGroup` but does not panic in
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// case of races between `Wait` and `Add` with a positive delta in the
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// state with a zero counter. The reason `sync.WaitGroup` panics is to
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// warn about a race condition. Using `WorkGroup` implicitly accept
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// these race conditions instead. Use sparingly and document why it is
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// used.
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type WorkGroup struct {
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mutex sync.Mutex
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cond *sync.Cond
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counter int
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}
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func (wg *WorkGroup) Wait() {
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wg.mutex.Lock()
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defer wg.mutex.Unlock()
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if wg.cond == nil {
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wg.cond = sync.NewCond(&wg.mutex)
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}
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for wg.counter > 0 {
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wg.cond.Wait()
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}
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}
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func (wg *WorkGroup) Add(delta int) {
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wg.mutex.Lock()
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defer wg.mutex.Unlock()
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if wg.cond == nil {
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wg.cond = sync.NewCond(&wg.mutex)
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}
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c := wg.counter + delta
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if c < 0 {
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panic(fmt.Sprintf("Adding %d would make workGroup counter negative: %d + %d = %d",
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delta, wg.counter, delta, c))
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}
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wg.counter = c
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if c == 0 {
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wg.cond.Broadcast()
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}
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}
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func (wg *WorkGroup) Done() {
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wg.Add(-1)
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}
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