From 2ab21d86f69c08c9cab261d3bf4d97954e673c9c Mon Sep 17 00:00:00 2001 From: Abhinav Gupta Date: Tue, 9 Aug 2022 16:56:14 -0700 Subject: [PATCH] Add Pointer[T] (#116) Adds a Pointer[T] type that provide the same functionality as Go 1.19's `sync/atomic.Pointer[T]` in both, Go 1.18 and 1.19. In Go 1.19, this uses the standard library's implementation, and in 1.18 our own custom implementation based on UnsafePointer. For Go 1.17, even though it's now unsupported, this is a no-op. Refs GO-1572 Resolves #115 --- go.mod | 6 ++-- pointer_go118.go | 60 +++++++++++++++++++++++++++++++ pointer_go119.go | 61 +++++++++++++++++++++++++++++++ pointer_test.go | 94 ++++++++++++++++++++++++++++++++++++++++++++++++ tools/go.mod | 4 +-- tools/go.sum | 29 ++------------- 6 files changed, 223 insertions(+), 31 deletions(-) create mode 100644 pointer_go118.go create mode 100644 pointer_go119.go create mode 100644 pointer_test.go diff --git a/go.mod b/go.mod index daa7599..69616f7 100644 --- a/go.mod +++ b/go.mod @@ -1,8 +1,10 @@ module go.uber.org/atomic +require github.com/stretchr/testify v1.3.0 + require ( github.com/davecgh/go-spew v1.1.1 // indirect - github.com/stretchr/testify v1.3.0 + github.com/pmezard/go-difflib v1.0.0 // indirect ) -go 1.13 +go 1.18 diff --git a/pointer_go118.go b/pointer_go118.go new file mode 100644 index 0000000..e0f47db --- /dev/null +++ b/pointer_go118.go @@ -0,0 +1,60 @@ +// Copyright (c) 2022 Uber Technologies, Inc. +// +// Permission is hereby granted, free of charge, to any person obtaining a copy +// of this software and associated documentation files (the "Software"), to deal +// in the Software without restriction, including without limitation the rights +// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell +// copies of the Software, and to permit persons to whom the Software is +// furnished to do so, subject to the following conditions: +// +// The above copyright notice and this permission notice shall be included in +// all copies or substantial portions of the Software. +// +// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR +// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, +// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE +// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER +// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, +// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN +// THE SOFTWARE. + +//go:build go1.18 && !go1.19 +// +build go1.18,!go1.19 + +package atomic + +import "unsafe" + +type Pointer[T any] struct { + _ nocmp // disallow non-atomic comparison + p UnsafePointer +} + +// NewPointer creates a new Pointer. +func NewPointer[T any](v *T) *Pointer[T] { + var p Pointer[T] + if v != nil { + p.p.Store(unsafe.Pointer(v)) + } + return &p +} + +// Load atomically loads the wrapped value. +func (p *Pointer[T]) Load() *T { + return (*T)(p.p.Load()) +} + +// Store atomically stores the passed value. +func (p *Pointer[T]) Store(val *T) { + p.p.Store(unsafe.Pointer(val)) +} + +// Swap atomically swaps the wrapped pointer and returns the old value. +func (p *Pointer[T]) Swap(val *T) (old *T) { + return (*T)(p.p.Swap(unsafe.Pointer(val))) +} + +// CompareAndSwap is an atomic compare-and-swap. +func (p *Pointer[T]) CompareAndSwap(old, new *T) (swapped bool) { + return p.p.CompareAndSwap(unsafe.Pointer(old), unsafe.Pointer(new)) +} diff --git a/pointer_go119.go b/pointer_go119.go new file mode 100644 index 0000000..6726f17 --- /dev/null +++ b/pointer_go119.go @@ -0,0 +1,61 @@ +// Copyright (c) 2022 Uber Technologies, Inc. +// +// Permission is hereby granted, free of charge, to any person obtaining a copy +// of this software and associated documentation files (the "Software"), to deal +// in the Software without restriction, including without limitation the rights +// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell +// copies of the Software, and to permit persons to whom the Software is +// furnished to do so, subject to the following conditions: +// +// The above copyright notice and this permission notice shall be included in +// all copies or substantial portions of the Software. +// +// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR +// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, +// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE +// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER +// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, +// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN +// THE SOFTWARE. + +//go:build go1.19 +// +build go1.19 + +package atomic + +import "sync/atomic" + +// Pointer is an atomic pointer of type *T. +type Pointer[T any] struct { + _ nocmp // disallow non-atomic comparison + p atomic.Pointer[T] +} + +// NewPointer creates a new Pointer. +func NewPointer[T any](v *T) *Pointer[T] { + var p Pointer[T] + if v != nil { + p.p.Store(v) + } + return &p +} + +// Load atomically loads the wrapped value. +func (p *Pointer[T]) Load() *T { + return p.p.Load() +} + +// Store atomically stores the passed value. +func (p *Pointer[T]) Store(val *T) { + p.p.Store(val) +} + +// Swap atomically swaps the wrapped pointer and returns the old value. +func (p *Pointer[T]) Swap(val *T) (old *T) { + return p.p.Swap(val) +} + +// CompareAndSwap is an atomic compare-and-swap. +func (p *Pointer[T]) CompareAndSwap(old, new *T) (swapped bool) { + return p.p.CompareAndSwap(old, new) +} diff --git a/pointer_test.go b/pointer_test.go new file mode 100644 index 0000000..ecd3763 --- /dev/null +++ b/pointer_test.go @@ -0,0 +1,94 @@ +// Copyright (c) 2022 Uber Technologies, Inc. +// +// Permission is hereby granted, free of charge, to any person obtaining a copy +// of this software and associated documentation files (the "Software"), to deal +// in the Software without restriction, including without limitation the rights +// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell +// copies of the Software, and to permit persons to whom the Software is +// furnished to do so, subject to the following conditions: +// +// The above copyright notice and this permission notice shall be included in +// all copies or substantial portions of the Software. +// +// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR +// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, +// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE +// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER +// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, +// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN +// THE SOFTWARE. + +//go:build go1.18 +// +build go1.18 + +package atomic + +import ( + "testing" + + "github.com/stretchr/testify/require" +) + +func TestPointer(t *testing.T) { + type foo struct{ v int } + + i := foo{42} + j := foo{0} + k := foo{1} + + tests := []struct { + desc string + newAtomic func() *Pointer[foo] + initial *foo + }{ + { + desc: "New", + newAtomic: func() *Pointer[foo] { + return NewPointer(&i) + }, + initial: &i, + }, + { + desc: "New/nil", + newAtomic: func() *Pointer[foo] { + return NewPointer[foo](nil) + }, + initial: nil, + }, + { + desc: "zero value", + newAtomic: func() *Pointer[foo] { + var p Pointer[foo] + return &p + }, + initial: nil, + }, + } + + for _, tt := range tests { + t.Run(tt.desc, func(t *testing.T) { + t.Run("Load", func(t *testing.T) { + atom := tt.newAtomic() + require.Equal(t, tt.initial, atom.Load(), "Load should report nil.") + }) + + t.Run("Swap", func(t *testing.T) { + atom := tt.newAtomic() + require.Equal(t, tt.initial, atom.Swap(&k), "Swap didn't return the old value.") + require.Equal(t, &k, atom.Load(), "Swap didn't set the correct value.") + }) + + t.Run("CAS", func(t *testing.T) { + atom := tt.newAtomic() + require.True(t, atom.CompareAndSwap(tt.initial, &j), "CAS didn't report a swap.") + require.Equal(t, &j, atom.Load(), "CAS didn't set the correct value.") + }) + + t.Run("Store", func(t *testing.T) { + atom := tt.newAtomic() + atom.Store(&i) + require.Equal(t, &i, atom.Load(), "Store didn't set the correct value.") + }) + }) + } +} diff --git a/tools/go.mod b/tools/go.mod index 552e683..932fcfe 100644 --- a/tools/go.mod +++ b/tools/go.mod @@ -1,6 +1,6 @@ module go.uber.org/atomic/tools -go 1.17 +go 1.18 require ( golang.org/x/lint v0.0.0-20210508222113-6edffad5e616 @@ -11,6 +11,6 @@ require ( github.com/BurntSushi/toml v1.2.0 // indirect golang.org/x/exp/typeparams v0.0.0-20220722155223-a9213eeb770e // indirect golang.org/x/mod v0.6.0-dev.0.20220419223038-86c51ed26bb4 // indirect - golang.org/x/sys v0.0.0-20220804214406-8e32c043e418 // indirect + golang.org/x/sys v0.0.0-20220808155132-1c4a2a72c664 // indirect golang.org/x/tools v0.1.12 // indirect ) diff --git a/tools/go.sum b/tools/go.sum index 0069e2e..ef08a0e 100644 --- a/tools/go.sum +++ b/tools/go.sum @@ -1,12 +1,7 @@ -github.com/BurntSushi/toml v0.4.1/go.mod h1:CxXYINrC8qIiEnFrOxCa7Jy5BFHlXnUU2pbicEuybxQ= github.com/BurntSushi/toml v1.2.0 h1:Rt8g24XnyGTyglgET/PRUNlrUeu9F5L+7FilkXfZgs0= github.com/BurntSushi/toml v1.2.0/go.mod h1:CxXYINrC8qIiEnFrOxCa7Jy5BFHlXnUU2pbicEuybxQ= -github.com/yuin/goldmark v1.4.1/go.mod h1:mwnBkeHKe2W/ZEtQ+71ViKU8L12m81fl3OWwC1Zlc8k= -github.com/yuin/goldmark v1.4.13/go.mod h1:6yULJ656Px+3vBD8DxQVa3kxgyrAnzto9xy5taEt/CY= golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w= golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI= -golang.org/x/crypto v0.0.0-20210921155107-089bfa567519/go.mod h1:GvvjBRRGRdwPK5ydBHafDWAxML/pGHZbMvKqRZ5+Abc= -golang.org/x/exp/typeparams v0.0.0-20220218215828-6cf2b201936e/go.mod h1:AbB0pIl9nAr9wVwH+Z2ZpaocVmF5I4GyWCDIsVjR0bk= golang.org/x/exp/typeparams v0.0.0-20220722155223-a9213eeb770e h1:7Xs2YCOpMlNqSQSmrrnhlzBXIE/bpMecZplbLePTJvE= golang.org/x/exp/typeparams v0.0.0-20220722155223-a9213eeb770e/go.mod h1:AbB0pIl9nAr9wVwH+Z2ZpaocVmF5I4GyWCDIsVjR0bk= golang.org/x/lint v0.0.0-20210508222113-6edffad5e616 h1:VLliZ0d+/avPrXXH+OakdXhpJuEoBZuwh1m2j7U6Iug= @@ -16,35 +11,15 @@ golang.org/x/mod v0.6.0-dev.0.20220419223038-86c51ed26bb4 h1:6zppjxzCulZykYSLyVD golang.org/x/mod v0.6.0-dev.0.20220419223038-86c51ed26bb4/go.mod h1:jJ57K6gSWd91VN4djpZkiMVwK6gcyfeH4XE8wZrZaV4= golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg= golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s= -golang.org/x/net v0.0.0-20210226172049-e18ecbb05110/go.mod h1:m0MpNAwzfU5UDzcl9v0D8zg8gWTRqZa9RBIspLL5mdg= -golang.org/x/net v0.0.0-20211015210444-4f30a5c0130f/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y= -golang.org/x/net v0.0.0-20220722155237-a158d28d115b/go.mod h1:XRhObCWvk6IyKnWLug+ECip1KBveYUHfp+8e9klMJ9c= golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM= -golang.org/x/sync v0.0.0-20210220032951-036812b2e83c/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM= -golang.org/x/sync v0.0.0-20220722155255-886fb9371eb4/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM= golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY= golang.org/x/sys 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v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo= -golang.org/x/term v0.0.0-20210927222741-03fcf44c2211/go.mod h1:jbD1KX2456YbFQfuXm/mYQcufACuNUgVhRMnK/tPxf8= +golang.org/x/sys v0.0.0-20220808155132-1c4a2a72c664 h1:v1W7bwXHsnLLloWYTVEdvGvA7BHMeBYsPcF0GLDxIRs= +golang.org/x/sys v0.0.0-20220808155132-1c4a2a72c664/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg= golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ= -golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ= -golang.org/x/text v0.3.6/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ= -golang.org/x/text v0.3.7/go.mod h1:u+2+/6zg+i71rQMx5EYifcz6MCKuco9NR6JIITiCfzQ= -golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ= -golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo= golang.org/x/tools 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