48 lines
1.2 KiB
Go
48 lines
1.2 KiB
Go
// Copyright 2022 PingCAP, Inc.
|
|
//
|
|
// 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 gpool
|
|
|
|
import (
|
|
"runtime"
|
|
"sync"
|
|
"sync/atomic"
|
|
)
|
|
|
|
type spinLock uint32
|
|
|
|
const maxBackoff = 16
|
|
|
|
func (sl *spinLock) Lock() {
|
|
backoff := 1
|
|
for !atomic.CompareAndSwapUint32((*uint32)(sl), 0, 1) {
|
|
// Leverage the exponential backoff algorithm, see https://en.wikipedia.org/wiki/Exponential_backoff.
|
|
for i := 0; i < backoff; i++ {
|
|
runtime.Gosched()
|
|
}
|
|
if backoff < maxBackoff {
|
|
backoff <<= 1
|
|
}
|
|
}
|
|
}
|
|
|
|
func (sl *spinLock) Unlock() {
|
|
atomic.StoreUint32((*uint32)(sl), 0)
|
|
}
|
|
|
|
// NewSpinLock instantiates a spin-lock.
|
|
func NewSpinLock() sync.Locker {
|
|
return new(spinLock)
|
|
}
|