Add Pointer[T]

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

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))
+}

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)
+}

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.")
+			})
+		})
+	}
+}

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
 )

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 v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20210423082822-04245dca01da/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20210615035016-665e8c7367d1/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.0.0-20211019181941-9d821ace8654/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.0.0-20220520151302-bc2c85ada10a/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.0.0-20220722155257-8c9f86f7a55f/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.0.0-20220804214406-8e32c043e418 h1:9vYwv7OjYaky/tlAeD7C4oC9EsPTlaFl1H2jS++V+ME=
-golang.org/x/sys v0.0.0-20220804214406-8e32c043e418/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/term 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 v0.0.0-20200130002326-2f3ba24bd6e7/go.mod h1:TB2adYChydJhpapKDTa4BR/hXlZSLoq2Wpct/0txZ28=
-golang.org/x/tools v0.1.11-0.20220513221640-090b14e8501f/go.mod h1:SgwaegtQh8clINPpECJMqnxLv9I09HLqnW3RMqW0CA4=
 golang.org/x/tools v0.1.12 h1:VveCTK38A2rkS8ZqFY25HIDFscX5X9OoEhJd3quQmXU=
 golang.org/x/tools v0.1.12/go.mod h1:hNGJHUnrk76NpqgfD5Aqm5Crs+Hm0VOH/i9J2+nxYbc=
-golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 honnef.co/go/tools v0.3.3 h1:oDx7VAwstgpYpb3wv0oxiZlxY+foCpRAwY7Vk6XpAgA=
 honnef.co/go/tools v0.3.3/go.mod h1:jzwdWgg7Jdq75wlfblQxO4neNaFFSvgc1tD5Wv8U0Yw=