mirror of
https://github.com/gohugoio/hugo.git
synced 2024-11-14 20:37:55 -05:00
68 lines
1.5 KiB
Go
68 lines
1.5 KiB
Go
// Copyright 2019 The Hugo Authors. All rights reserved.
|
|
//
|
|
// 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 lazy
|
|
|
|
import (
|
|
"sync"
|
|
"sync/atomic"
|
|
)
|
|
|
|
// onceMore is similar to sync.Once.
|
|
//
|
|
// Additional features are:
|
|
// * it can be reset, so the action can be repeated if needed
|
|
// * it has methods to check if it's done or in progress
|
|
|
|
type onceMore struct {
|
|
mu sync.Mutex
|
|
lock uint32
|
|
done uint32
|
|
}
|
|
|
|
func (t *onceMore) Do(f func()) {
|
|
if atomic.LoadUint32(&t.done) == 1 {
|
|
return
|
|
}
|
|
|
|
// f may call this Do and we would get a deadlock.
|
|
locked := atomic.CompareAndSwapUint32(&t.lock, 0, 1)
|
|
if !locked {
|
|
return
|
|
}
|
|
defer atomic.StoreUint32(&t.lock, 0)
|
|
|
|
t.mu.Lock()
|
|
defer t.mu.Unlock()
|
|
|
|
// Double check
|
|
if t.done == 1 {
|
|
return
|
|
}
|
|
defer atomic.StoreUint32(&t.done, 1)
|
|
f()
|
|
}
|
|
|
|
func (t *onceMore) InProgress() bool {
|
|
return atomic.LoadUint32(&t.lock) == 1
|
|
}
|
|
|
|
func (t *onceMore) Done() bool {
|
|
return atomic.LoadUint32(&t.done) == 1
|
|
}
|
|
|
|
func (t *onceMore) ResetWithLock() *sync.Mutex {
|
|
t.mu.Lock()
|
|
defer atomic.StoreUint32(&t.done, 0)
|
|
return &t.mu
|
|
}
|