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