41 lines
1008 B
Go
41 lines
1008 B
Go
|
/*
|
|||
|
|
* Copyright (C) THL A29 Limited, a Tencent company. All rights reserved.
|
|||
|
|
*
|
|||
|
|
* SPDX-License-Identifier: Apache-2.0
|
|||
|
|
*
|
|||
|
|
*/
|
|||
|
|
|
|||
|
|
package lockfree
|
|||
|
|
|
|||
|
|
import "sync/atomic"
|
|||
|
|
|
|||
|
|
// cursor 游标，一直持续增长的一个uint64序列
|
|||
|
|
// 该序列用于wg（Write Goroutine）获取对应写入到buffer中元素的位置操作
|
|||
|
|
// 通过使用atomic操作避免锁，提高性能
|
|||
|
|
// 通过使用padding填充的方式，填充前面和后面各使用7个uint64（缓存行填充），避免伪共享问题
|
|||
|
|
type cursor struct {
|
|||
|
|
p1, p2, p3, p4, p5, p6, p7 uint64
|
|||
|
|
v uint64
|
|||
|
|
p9, p10, p11, p12, p13, p14, p15 uint64
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
func newCursor() *cursor {
|
|||
|
|
return &cursor{}
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
func (c *cursor) increment() uint64 {
|
|||
|
|
return atomic.AddUint64(&c.v, 1)
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
func (c *cursor) atomicLoad() uint64 {
|
|||
|
|
return atomic.LoadUint64(&c.v)
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
func (c *cursor) load() uint64 {
|
|||
|
|
return c.v
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
func (c *cursor) store(expectVal, newVal uint64) bool {
|
|||
|
|
return atomic.CompareAndSwapUint64(&c.v, expectVal, newVal)
|
|||
|
|
}
|