5788befcf4
* Add tests reproducing the panics * Add v2 of the test * Use tailor-made workGroup to mimic sync.WaitGroup * Lint * CHANGELOG
72 lines
1.6 KiB
Go
72 lines
1.6 KiB
Go
// Copyright 2016-2021, Pulumi Corporation.
|
|
//
|
|
// 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 pulumi
|
|
|
|
import (
|
|
"fmt"
|
|
"sync"
|
|
)
|
|
|
|
// Mimicks the interface of `sync.WaitGroup` but does not panic in
|
|
// case of races between `Wait` and `Add` with a positive delta in the
|
|
// state with a zero counter. The reason `sync.WaitGroup` panics is to
|
|
// warn about a race condition. Using `workGroup` implicitly accept
|
|
// these race conditions instead. Use sparingly and document why it is
|
|
// used.
|
|
type workGroup struct {
|
|
mutex sync.Mutex
|
|
cond *sync.Cond
|
|
counter int
|
|
}
|
|
|
|
func (wg *workGroup) Wait() {
|
|
wg.mutex.Lock()
|
|
defer wg.mutex.Unlock()
|
|
|
|
if wg.cond == nil {
|
|
wg.cond = sync.NewCond(&wg.mutex)
|
|
}
|
|
|
|
for wg.counter > 0 {
|
|
wg.cond.Wait()
|
|
}
|
|
}
|
|
|
|
func (wg *workGroup) Add(delta int) {
|
|
wg.mutex.Lock()
|
|
defer wg.mutex.Unlock()
|
|
|
|
if wg.cond == nil {
|
|
wg.cond = sync.NewCond(&wg.mutex)
|
|
}
|
|
|
|
c := wg.counter + delta
|
|
|
|
if c < 0 {
|
|
panic(fmt.Sprintf("Adding %d would make workGroup counter negative: %d + %d = %d",
|
|
delta, wg.counter, delta, c))
|
|
}
|
|
|
|
wg.counter = c
|
|
|
|
if c == 0 {
|
|
wg.cond.Broadcast()
|
|
}
|
|
}
|
|
|
|
func (wg *workGroup) Done() {
|
|
wg.Add(-1)
|
|
}
|