1 // Copyright (c) 2022 Uber Technologies, Inc.
2 //
3 // Permission is hereby granted, free of charge, to any person obtaining a copy
4 // of this software and associated documentation files (the "Software"), to deal
5 // in the Software without restriction, including without limitation the rights
6 // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
7 // copies of the Software, and to permit persons to whom the Software is
8 // furnished to do so, subject to the following conditions:
9 //
10 // The above copyright notice and this permission notice shall be included in
11 // all copies or substantial portions of the Software.
12 //
13 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
14 // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
15 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
16 // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
17 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
18 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
19 // THE SOFTWARE.
20 21 //go:build go1.18 && !go1.19
22 // +build go1.18,!go1.19
23 24 package atomic
25 26 import "unsafe"
27 28 type Pointer[T any] struct {
29 _ nocmp // disallow non-atomic comparison
30 p UnsafePointer
31 }
32 33 // NewPointer creates a new Pointer.
34 func NewPointer[T any](v *T) *Pointer[T] {
35 var p Pointer[T]
36 if v != nil {
37 p.p.Store(unsafe.Pointer(v))
38 }
39 return &p
40 }
41 42 // Load atomically loads the wrapped value.
43 func (p *Pointer[T]) Load() *T {
44 return (*T)(p.p.Load())
45 }
46 47 // Store atomically stores the passed value.
48 func (p *Pointer[T]) Store(val *T) {
49 p.p.Store(unsafe.Pointer(val))
50 }
51 52 // Swap atomically swaps the wrapped pointer and returns the old value.
53 func (p *Pointer[T]) Swap(val *T) (old *T) {
54 return (*T)(p.p.Swap(unsafe.Pointer(val)))
55 }
56 57 // CompareAndSwap is an atomic compare-and-swap.
58 func (p *Pointer[T]) CompareAndSwap(old, new *T) (swapped bool) {
59 return p.p.CompareAndSwap(unsafe.Pointer(old), unsafe.Pointer(new))
60 }
61