Generate all atomics automatically (#77)
`gen-valuewrapper` is specialized to generating type-safe atomic
wrappers around `atomic.Value`. This limitation is unnecessary. Given
functions to convert an exposed type to the underlying type (referred to
as "packing" here) and back ("unpacking"), we can generate wrappers
around any backing atomic type.
This generalizes `valuewrapper` into an `atomicwrapper` implementing
said functionality, and adding opt-in support for generating CAS, Swap,
and JSON methods.
With this, we can automatically generate bool, float64, and
time.Duration atomic wrappers on top of Uint32, Uint64, and Int64
respectively, as well as their core functionality.
diff --git a/Makefile b/Makefile
index 7203311..e3b3c2c 100644
--- a/Makefile
+++ b/Makefile
@@ -3,14 +3,14 @@
GOLINT = $(GOBIN)/golint
GEN_ATOMICINT = $(GOBIN)/gen-atomicint
-GEN_VALUEWRAPPER = $(GOBIN)/gen-valuewrapper
+GEN_ATOMICWRAPPER = $(GOBIN)/gen-atomicwrapper
GO_FILES ?= $(shell find . '(' -path .git -o -path vendor ')' -prune -o -name '*.go' -print)
# Also update ignore section in .codecov.yml.
COVER_IGNORE_PKGS = \
go.uber.org/atomic/internal/gen-atomicint \
- go.uber.org/atomic/internal/gen-valuewrapper
+ go.uber.org/atomic/internal/gen-atomicwrapper
.PHONY: build
build:
@@ -29,8 +29,8 @@
$(GOLINT):
go install golang.org/x/lint/golint
-$(GEN_VALUEWRAPPER): $(wildcard ./internal/gen-valuewrapper/*)
- go build -o $@ ./internal/gen-valuewrapper
+$(GEN_ATOMICWRAPPER): $(wildcard ./internal/gen-atomicwrapper/*)
+ go build -o $@ ./internal/gen-atomicwrapper
$(GEN_ATOMICINT): $(wildcard ./internal/gen-atomicint/*)
go build -o $@ ./internal/gen-atomicint
@@ -54,7 +54,7 @@
go tool cover -html=cover.out -o cover.html
.PHONY: generate
-generate: $(GEN_ATOMICINT) $(GEN_VALUEWRAPPER)
+generate: $(GEN_ATOMICINT) $(GEN_ATOMICWRAPPER)
go generate ./...
.PHONY: generatenodirty
diff --git a/atomic.go b/atomic.go
deleted file mode 100644
index 8bdf5d7..0000000
--- a/atomic.go
+++ /dev/null
@@ -1,238 +0,0 @@
-// Copyright (c) 2016-2020 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.
-
-// Package atomic provides simple wrappers around numerics to enforce atomic
-// access.
-package atomic
-
-import (
- "encoding/json"
- "math"
- "strconv"
- "sync/atomic"
- "time"
-)
-
-// Bool is an atomic Boolean.
-type Bool struct {
- nocmp // disallow non-atomic comparison
-
- v uint32
-}
-
-// NewBool creates a Bool.
-func NewBool(initial bool) *Bool {
- return &Bool{v: boolToInt(initial)}
-}
-
-// Load atomically loads the Boolean.
-func (b *Bool) Load() bool {
- return truthy(atomic.LoadUint32(&b.v))
-}
-
-// CAS is an atomic compare-and-swap.
-func (b *Bool) CAS(old, new bool) bool {
- return atomic.CompareAndSwapUint32(&b.v, boolToInt(old), boolToInt(new))
-}
-
-// Store atomically stores the passed value.
-func (b *Bool) Store(new bool) {
- atomic.StoreUint32(&b.v, boolToInt(new))
-}
-
-// Swap sets the given value and returns the previous value.
-func (b *Bool) Swap(new bool) bool {
- return truthy(atomic.SwapUint32(&b.v, boolToInt(new)))
-}
-
-// Toggle atomically negates the Boolean and returns the previous value.
-func (b *Bool) Toggle() bool {
- for {
- old := b.Load()
- if b.CAS(old, !old) {
- return old
- }
- }
-}
-
-func truthy(n uint32) bool {
- return n == 1
-}
-
-func boolToInt(b bool) uint32 {
- if b {
- return 1
- }
- return 0
-}
-
-// MarshalJSON encodes the wrapped bool into JSON.
-func (b *Bool) MarshalJSON() ([]byte, error) {
- return json.Marshal(b.Load())
-}
-
-// UnmarshalJSON decodes JSON into the wrapped bool.
-func (b *Bool) UnmarshalJSON(t []byte) error {
- var v bool
- if err := json.Unmarshal(t, &v); err != nil {
- return err
- }
- b.Store(v)
- return nil
-}
-
-// String encodes the wrapped value as a string.
-func (b *Bool) String() string {
- return strconv.FormatBool(b.Load())
-}
-
-// Float64 is an atomic wrapper around float64.
-type Float64 struct {
- nocmp // disallow non-atomic comparison
-
- v uint64
-}
-
-// NewFloat64 creates a Float64.
-func NewFloat64(f float64) *Float64 {
- return &Float64{v: math.Float64bits(f)}
-}
-
-// Load atomically loads the wrapped value.
-func (f *Float64) Load() float64 {
- return math.Float64frombits(atomic.LoadUint64(&f.v))
-}
-
-// Store atomically stores the passed value.
-func (f *Float64) Store(s float64) {
- atomic.StoreUint64(&f.v, math.Float64bits(s))
-}
-
-// Add atomically adds to the wrapped float64 and returns the new value.
-func (f *Float64) Add(s float64) float64 {
- for {
- old := f.Load()
- new := old + s
- if f.CAS(old, new) {
- return new
- }
- }
-}
-
-// Sub atomically subtracts from the wrapped float64 and returns the new value.
-func (f *Float64) Sub(s float64) float64 {
- return f.Add(-s)
-}
-
-// CAS is an atomic compare-and-swap.
-func (f *Float64) CAS(old, new float64) bool {
- return atomic.CompareAndSwapUint64(&f.v, math.Float64bits(old), math.Float64bits(new))
-}
-
-// MarshalJSON encodes the wrapped float64 into JSON.
-func (f *Float64) MarshalJSON() ([]byte, error) {
- return json.Marshal(f.Load())
-}
-
-// UnmarshalJSON decodes JSON into the wrapped float64.
-func (f *Float64) UnmarshalJSON(b []byte) error {
- var v float64
- if err := json.Unmarshal(b, &v); err != nil {
- return err
- }
- f.Store(v)
- return nil
-}
-
-// String encodes the wrapped value as a string.
-func (f *Float64) String() string {
- // 'g' is the behavior for floats with %v.
- return strconv.FormatFloat(f.Load(), 'g', -1, 64)
-}
-
-// Duration is an atomic wrapper around time.Duration
-// https://godoc.org/time#Duration
-type Duration struct {
- nocmp // disallow non-atomic comparison
-
- v Int64
-}
-
-// NewDuration creates a Duration.
-func NewDuration(d time.Duration) *Duration {
- return &Duration{v: *NewInt64(int64(d))}
-}
-
-// Load atomically loads the wrapped value.
-func (d *Duration) Load() time.Duration {
- return time.Duration(d.v.Load())
-}
-
-// Store atomically stores the passed value.
-func (d *Duration) Store(n time.Duration) {
- d.v.Store(int64(n))
-}
-
-// Add atomically adds to the wrapped time.Duration and returns the new value.
-func (d *Duration) Add(n time.Duration) time.Duration {
- return time.Duration(d.v.Add(int64(n)))
-}
-
-// Sub atomically subtracts from the wrapped time.Duration and returns the new value.
-func (d *Duration) Sub(n time.Duration) time.Duration {
- return time.Duration(d.v.Sub(int64(n)))
-}
-
-// Swap atomically swaps the wrapped time.Duration and returns the old value.
-func (d *Duration) Swap(n time.Duration) time.Duration {
- return time.Duration(d.v.Swap(int64(n)))
-}
-
-// CAS is an atomic compare-and-swap.
-func (d *Duration) CAS(old, new time.Duration) bool {
- return d.v.CAS(int64(old), int64(new))
-}
-
-// MarshalJSON encodes the wrapped time.Duration into JSON.
-func (d *Duration) MarshalJSON() ([]byte, error) {
- return json.Marshal(d.Load())
-}
-
-// UnmarshalJSON decodes JSON into the wrapped time.Duration.
-func (d *Duration) UnmarshalJSON(b []byte) error {
- var v time.Duration
- if err := json.Unmarshal(b, &v); err != nil {
- return err
- }
- d.Store(v)
- return nil
-}
-
-// String encodes the wrapped value as a string.
-func (d *Duration) String() string {
- return d.Load().String()
-}
-
-// Value shadows the type of the same name from sync/atomic
-// https://godoc.org/sync/atomic#Value
-type Value struct {
- nocmp // disallow non-atomic comparison
- atomic.Value
-}
diff --git a/atomic_test.go b/atomic_test.go
deleted file mode 100644
index cb3768e..0000000
--- a/atomic_test.go
+++ /dev/null
@@ -1,182 +0,0 @@
-// Copyright (c) 2016-2020 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.
-
-package atomic
-
-import (
- "encoding/json"
- "testing"
- "time"
-
- "github.com/stretchr/testify/assert"
- "github.com/stretchr/testify/require"
-)
-
-func TestBool(t *testing.T) {
- atom := NewBool(false)
- require.False(t, atom.Toggle(), "Expected Toggle to return previous value.")
- require.True(t, atom.Toggle(), "Expected Toggle to return previous value.")
- require.False(t, atom.Toggle(), "Expected Toggle to return previous value.")
- require.True(t, atom.Load(), "Unexpected state after swap.")
-
- require.True(t, atom.CAS(true, true), "CAS should swap when old matches")
- require.True(t, atom.Load(), "CAS should have no effect")
- require.True(t, atom.CAS(true, false), "CAS should swap when old matches")
- require.False(t, atom.Load(), "CAS should have modified the value")
- require.False(t, atom.CAS(true, false), "CAS should fail on old mismatch")
- require.False(t, atom.Load(), "CAS should not have modified the value")
-
- atom.Store(false)
- require.False(t, atom.Load(), "Unexpected state after store.")
-
- prev := atom.Swap(false)
- require.False(t, prev, "Expected Swap to return previous value.")
-
- prev = atom.Swap(true)
- require.False(t, prev, "Expected Swap to return previous value.")
-
- t.Run("JSON/Marshal", func(t *testing.T) {
- atom.Store(true)
- bytes, err := json.Marshal(atom)
- require.NoError(t, err, "json.Marshal errored unexpectedly.")
- require.Equal(t, []byte("true"), bytes, "json.Marshal encoded the wrong bytes.")
- })
-
- t.Run("JSON/Unmarshal", func(t *testing.T) {
- err := json.Unmarshal([]byte("false"), &atom)
- require.NoError(t, err, "json.Unmarshal errored unexpectedly.")
- require.False(t, atom.Load(), "json.Unmarshal didn't set the correct value.")
- })
-
- t.Run("JSON/Unmarshal/Error", func(t *testing.T) {
- err := json.Unmarshal([]byte("42"), &atom)
- require.Error(t, err, "json.Unmarshal didn't error as expected.")
- assertErrorJSONUnmarshalType(t, err,
- "json.Unmarshal failed with unexpected error %v, want UnmarshalTypeError.", err)
- })
-
- t.Run("String", func(t *testing.T) {
- t.Run("true", func(t *testing.T) {
- assert.Equal(t, "true", NewBool(true).String(),
- "String() returned an unexpected value.")
- })
-
- t.Run("false", func(t *testing.T) {
- var b Bool
- assert.Equal(t, "false", b.String(),
- "String() returned an unexpected value.")
- })
- })
-}
-
-func TestFloat64(t *testing.T) {
- atom := NewFloat64(4.2)
-
- require.Equal(t, float64(4.2), atom.Load(), "Load didn't work.")
-
- require.True(t, atom.CAS(4.2, 0.5), "CAS didn't report a swap.")
- require.Equal(t, float64(0.5), atom.Load(), "CAS didn't set the correct value.")
- require.False(t, atom.CAS(0.0, 1.5), "CAS reported a swap.")
-
- atom.Store(42.0)
- require.Equal(t, float64(42.0), atom.Load(), "Store didn't set the correct value.")
- require.Equal(t, float64(42.5), atom.Add(0.5), "Add didn't work.")
- require.Equal(t, float64(42.0), atom.Sub(0.5), "Sub didn't work.")
-
- t.Run("JSON/Marshal", func(t *testing.T) {
- atom.Store(42.5)
- bytes, err := json.Marshal(atom)
- require.NoError(t, err, "json.Marshal errored unexpectedly.")
- require.Equal(t, []byte("42.5"), bytes, "json.Marshal encoded the wrong bytes.")
- })
-
- t.Run("JSON/Unmarshal", func(t *testing.T) {
- err := json.Unmarshal([]byte("40.5"), &atom)
- require.NoError(t, err, "json.Unmarshal errored unexpectedly.")
- require.Equal(t, float64(40.5), atom.Load(), "json.Unmarshal didn't set the correct value.")
- })
-
- t.Run("JSON/Unmarshal/Error", func(t *testing.T) {
- err := json.Unmarshal([]byte("\"40.5\""), &atom)
- require.Error(t, err, "json.Unmarshal didn't error as expected.")
- assertErrorJSONUnmarshalType(t, err,
- "json.Unmarshal failed with unexpected error %v, want UnmarshalTypeError.", err)
- })
-
- t.Run("String", func(t *testing.T) {
- assert.Equal(t, "42.5", NewFloat64(42.5).String(),
- "String() returned an unexpected value.")
- })
-}
-
-func TestDuration(t *testing.T) {
- atom := NewDuration(5 * time.Minute)
-
- require.Equal(t, 5*time.Minute, atom.Load(), "Load didn't work.")
- require.Equal(t, 6*time.Minute, atom.Add(time.Minute), "Add didn't work.")
- require.Equal(t, 4*time.Minute, atom.Sub(2*time.Minute), "Sub didn't work.")
-
- require.True(t, atom.CAS(4*time.Minute, time.Minute), "CAS didn't report a swap.")
- require.Equal(t, time.Minute, atom.Load(), "CAS didn't set the correct value.")
-
- require.Equal(t, time.Minute, atom.Swap(2*time.Minute), "Swap didn't return the old value.")
- require.Equal(t, 2*time.Minute, atom.Load(), "Swap didn't set the correct value.")
-
- atom.Store(10 * time.Minute)
- require.Equal(t, 10*time.Minute, atom.Load(), "Store didn't set the correct value.")
-
- t.Run("JSON/Marshal", func(t *testing.T) {
- atom.Store(time.Second)
- bytes, err := json.Marshal(atom)
- require.NoError(t, err, "json.Marshal errored unexpectedly.")
- require.Equal(t, []byte("1000000000"), bytes, "json.Marshal encoded the wrong bytes.")
- })
-
- t.Run("JSON/Unmarshal", func(t *testing.T) {
- err := json.Unmarshal([]byte("1000000000"), &atom)
- require.NoError(t, err, "json.Unmarshal errored unexpectedly.")
- require.Equal(t, time.Second, atom.Load(), "json.Unmarshal didn't set the correct value.")
- })
-
- t.Run("JSON/Unmarshal/Error", func(t *testing.T) {
- err := json.Unmarshal([]byte("\"1000000000\""), &atom)
- require.Error(t, err, "json.Unmarshal didn't error as expected.")
- assertErrorJSONUnmarshalType(t, err,
- "json.Unmarshal failed with unexpected error %v, want UnmarshalTypeError.", err)
- })
-
- t.Run("String", func(t *testing.T) {
- assert.Equal(t, "42s", NewDuration(42*time.Second).String(),
- "String() returned an unexpected value.")
- })
-}
-
-func TestValue(t *testing.T) {
- var v Value
- assert.Nil(t, v.Load(), "initial Value is not nil")
-
- v.Store(42)
- assert.Equal(t, 42, v.Load())
-
- v.Store(84)
- assert.Equal(t, 84, v.Load())
-
- assert.Panics(t, func() { v.Store("foo") })
-}
diff --git a/bool.go b/bool.go
new file mode 100644
index 0000000..1bf3fa0
--- /dev/null
+++ b/bool.go
@@ -0,0 +1,81 @@
+// @generated Code generated by gen-atomicwrapper.
+
+// Copyright (c) 2020 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.
+
+package atomic
+
+import (
+ "encoding/json"
+)
+
+// Bool is an atomic type-safe wrapper for bool values.
+type Bool struct {
+ nocmp // disallow non-atomic comparison
+
+ v Uint32
+}
+
+var _zeroBool bool
+
+// NewBool creates a new Bool.
+func NewBool(v bool) *Bool {
+ x := &Bool{}
+ if v != _zeroBool {
+ x.Store(v)
+ }
+ return x
+}
+
+// Load atomically loads the wrapped bool.
+func (x *Bool) Load() bool {
+ return truthy(x.v.Load())
+}
+
+// Store atomically stores the passed bool.
+func (x *Bool) Store(v bool) {
+ x.v.Store(boolToInt(v))
+}
+
+// CAS is an atomic compare-and-swap for bool values.
+func (x *Bool) CAS(o, n bool) bool {
+ return x.v.CAS(boolToInt(o), boolToInt(n))
+}
+
+// Swap atomically stores the given bool and returns the old
+// value.
+func (x *Bool) Swap(o bool) bool {
+ return truthy(x.v.Swap(boolToInt(o)))
+}
+
+// MarshalJSON encodes the wrapped bool into JSON.
+func (x *Bool) MarshalJSON() ([]byte, error) {
+ return json.Marshal(x.Load())
+}
+
+// UnmarshalJSON decodes a bool from JSON.
+func (x *Bool) UnmarshalJSON(b []byte) error {
+ var v bool
+ if err := json.Unmarshal(b, &v); err != nil {
+ return err
+ }
+ x.Store(v)
+ return nil
+}
diff --git a/bool_ext.go b/bool_ext.go
new file mode 100644
index 0000000..c7bf7a8
--- /dev/null
+++ b/bool_ext.go
@@ -0,0 +1,53 @@
+// Copyright (c) 2020 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.
+
+package atomic
+
+import (
+ "strconv"
+)
+
+//go:generate bin/gen-atomicwrapper -name=Bool -type=bool -wrapped=Uint32 -pack=boolToInt -unpack=truthy -cas -swap -json -file=bool.go
+
+func truthy(n uint32) bool {
+ return n == 1
+}
+
+func boolToInt(b bool) uint32 {
+ if b {
+ return 1
+ }
+ return 0
+}
+
+// Toggle atomically negates the Boolean and returns the previous value.
+func (b *Bool) Toggle() bool {
+ for {
+ old := b.Load()
+ if b.CAS(old, !old) {
+ return old
+ }
+ }
+}
+
+// String encodes the wrapped value as a string.
+func (b *Bool) String() string {
+ return strconv.FormatBool(b.Load())
+}
diff --git a/bool_test.go b/bool_test.go
new file mode 100644
index 0000000..bcba01d
--- /dev/null
+++ b/bool_test.go
@@ -0,0 +1,86 @@
+// Copyright (c) 2020 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.
+
+package atomic
+
+import (
+ "encoding/json"
+ "testing"
+
+ "github.com/stretchr/testify/assert"
+ "github.com/stretchr/testify/require"
+)
+
+func TestBool(t *testing.T) {
+ atom := NewBool(false)
+ require.False(t, atom.Toggle(), "Expected Toggle to return previous value.")
+ require.True(t, atom.Toggle(), "Expected Toggle to return previous value.")
+ require.False(t, atom.Toggle(), "Expected Toggle to return previous value.")
+ require.True(t, atom.Load(), "Unexpected state after swap.")
+
+ require.True(t, atom.CAS(true, true), "CAS should swap when old matches")
+ require.True(t, atom.Load(), "CAS should have no effect")
+ require.True(t, atom.CAS(true, false), "CAS should swap when old matches")
+ require.False(t, atom.Load(), "CAS should have modified the value")
+ require.False(t, atom.CAS(true, false), "CAS should fail on old mismatch")
+ require.False(t, atom.Load(), "CAS should not have modified the value")
+
+ atom.Store(false)
+ require.False(t, atom.Load(), "Unexpected state after store.")
+
+ prev := atom.Swap(false)
+ require.False(t, prev, "Expected Swap to return previous value.")
+
+ prev = atom.Swap(true)
+ require.False(t, prev, "Expected Swap to return previous value.")
+
+ t.Run("JSON/Marshal", func(t *testing.T) {
+ atom.Store(true)
+ bytes, err := json.Marshal(atom)
+ require.NoError(t, err, "json.Marshal errored unexpectedly.")
+ require.Equal(t, []byte("true"), bytes, "json.Marshal encoded the wrong bytes.")
+ })
+
+ t.Run("JSON/Unmarshal", func(t *testing.T) {
+ err := json.Unmarshal([]byte("false"), &atom)
+ require.NoError(t, err, "json.Unmarshal errored unexpectedly.")
+ require.False(t, atom.Load(), "json.Unmarshal didn't set the correct value.")
+ })
+
+ t.Run("JSON/Unmarshal/Error", func(t *testing.T) {
+ err := json.Unmarshal([]byte("42"), &atom)
+ require.Error(t, err, "json.Unmarshal didn't error as expected.")
+ assertErrorJSONUnmarshalType(t, err,
+ "json.Unmarshal failed with unexpected error %v, want UnmarshalTypeError.", err)
+ })
+
+ t.Run("String", func(t *testing.T) {
+ t.Run("true", func(t *testing.T) {
+ assert.Equal(t, "true", NewBool(true).String(),
+ "String() returned an unexpected value.")
+ })
+
+ t.Run("false", func(t *testing.T) {
+ var b Bool
+ assert.Equal(t, "false", b.String(),
+ "String() returned an unexpected value.")
+ })
+ })
+}
diff --git a/doc.go b/doc.go
new file mode 100644
index 0000000..ae7390e
--- /dev/null
+++ b/doc.go
@@ -0,0 +1,23 @@
+// Copyright (c) 2020 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.
+
+// Package atomic provides simple wrappers around numerics to enforce atomic
+// access.
+package atomic
diff --git a/duration.go b/duration.go
new file mode 100644
index 0000000..30ed6aa
--- /dev/null
+++ b/duration.go
@@ -0,0 +1,82 @@
+// @generated Code generated by gen-atomicwrapper.
+
+// Copyright (c) 2020 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.
+
+package atomic
+
+import (
+ "encoding/json"
+ "time"
+)
+
+// Duration is an atomic type-safe wrapper for time.Duration values.
+type Duration struct {
+ nocmp // disallow non-atomic comparison
+
+ v Int64
+}
+
+var _zeroDuration time.Duration
+
+// NewDuration creates a new Duration.
+func NewDuration(v time.Duration) *Duration {
+ x := &Duration{}
+ if v != _zeroDuration {
+ x.Store(v)
+ }
+ return x
+}
+
+// Load atomically loads the wrapped time.Duration.
+func (x *Duration) Load() time.Duration {
+ return time.Duration(x.v.Load())
+}
+
+// Store atomically stores the passed time.Duration.
+func (x *Duration) Store(v time.Duration) {
+ x.v.Store(int64(v))
+}
+
+// CAS is an atomic compare-and-swap for time.Duration values.
+func (x *Duration) CAS(o, n time.Duration) bool {
+ return x.v.CAS(int64(o), int64(n))
+}
+
+// Swap atomically stores the given time.Duration and returns the old
+// value.
+func (x *Duration) Swap(o time.Duration) time.Duration {
+ return time.Duration(x.v.Swap(int64(o)))
+}
+
+// MarshalJSON encodes the wrapped time.Duration into JSON.
+func (x *Duration) MarshalJSON() ([]byte, error) {
+ return json.Marshal(x.Load())
+}
+
+// UnmarshalJSON decodes a time.Duration from JSON.
+func (x *Duration) UnmarshalJSON(b []byte) error {
+ var v time.Duration
+ if err := json.Unmarshal(b, &v); err != nil {
+ return err
+ }
+ x.Store(v)
+ return nil
+}
diff --git a/duration_ext.go b/duration_ext.go
new file mode 100644
index 0000000..6273b66
--- /dev/null
+++ b/duration_ext.go
@@ -0,0 +1,40 @@
+// Copyright (c) 2020 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.
+
+package atomic
+
+import "time"
+
+//go:generate bin/gen-atomicwrapper -name=Duration -type=time.Duration -wrapped=Int64 -pack=int64 -unpack=time.Duration -cas -swap -json -imports time -file=duration.go
+
+// Add atomically adds to the wrapped time.Duration and returns the new value.
+func (d *Duration) Add(n time.Duration) time.Duration {
+ return time.Duration(d.v.Add(int64(n)))
+}
+
+// Sub atomically subtracts from the wrapped time.Duration and returns the new value.
+func (d *Duration) Sub(n time.Duration) time.Duration {
+ return time.Duration(d.v.Sub(int64(n)))
+}
+
+// String encodes the wrapped value as a string.
+func (d *Duration) String() string {
+ return d.Load().String()
+}
diff --git a/duration_test.go b/duration_test.go
new file mode 100644
index 0000000..bc5cea5
--- /dev/null
+++ b/duration_test.go
@@ -0,0 +1,72 @@
+// Copyright (c) 2020 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.
+
+package atomic
+
+import (
+ "encoding/json"
+ "testing"
+ "time"
+
+ "github.com/stretchr/testify/assert"
+ "github.com/stretchr/testify/require"
+)
+
+func TestDuration(t *testing.T) {
+ atom := NewDuration(5 * time.Minute)
+
+ require.Equal(t, 5*time.Minute, atom.Load(), "Load didn't work.")
+ require.Equal(t, 6*time.Minute, atom.Add(time.Minute), "Add didn't work.")
+ require.Equal(t, 4*time.Minute, atom.Sub(2*time.Minute), "Sub didn't work.")
+
+ require.True(t, atom.CAS(4*time.Minute, time.Minute), "CAS didn't report a swap.")
+ require.Equal(t, time.Minute, atom.Load(), "CAS didn't set the correct value.")
+
+ require.Equal(t, time.Minute, atom.Swap(2*time.Minute), "Swap didn't return the old value.")
+ require.Equal(t, 2*time.Minute, atom.Load(), "Swap didn't set the correct value.")
+
+ atom.Store(10 * time.Minute)
+ require.Equal(t, 10*time.Minute, atom.Load(), "Store didn't set the correct value.")
+
+ t.Run("JSON/Marshal", func(t *testing.T) {
+ atom.Store(time.Second)
+ bytes, err := json.Marshal(atom)
+ require.NoError(t, err, "json.Marshal errored unexpectedly.")
+ require.Equal(t, []byte("1000000000"), bytes, "json.Marshal encoded the wrong bytes.")
+ })
+
+ t.Run("JSON/Unmarshal", func(t *testing.T) {
+ err := json.Unmarshal([]byte("1000000000"), &atom)
+ require.NoError(t, err, "json.Unmarshal errored unexpectedly.")
+ require.Equal(t, time.Second, atom.Load(), "json.Unmarshal didn't set the correct value.")
+ })
+
+ t.Run("JSON/Unmarshal/Error", func(t *testing.T) {
+ err := json.Unmarshal([]byte("\"1000000000\""), &atom)
+ require.Error(t, err, "json.Unmarshal didn't error as expected.")
+ assertErrorJSONUnmarshalType(t, err,
+ "json.Unmarshal failed with unexpected error %v, want UnmarshalTypeError.", err)
+ })
+
+ t.Run("String", func(t *testing.T) {
+ assert.Equal(t, "42s", NewDuration(42*time.Second).String(),
+ "String() returned an unexpected value.")
+ })
+}
diff --git a/error.go b/error.go
index 8657849..cedbc91 100644
--- a/error.go
+++ b/error.go
@@ -1,4 +1,4 @@
-// @generated Code generated by gen-valuewrapper.
+// @generated Code generated by gen-atomicwrapper.
// Copyright (c) 2020 Uber Technologies, Inc.
//
@@ -23,22 +23,18 @@
package atomic
// Error is an atomic type-safe wrapper for error values.
-type Error struct{ v Value }
+type Error struct {
+ nocmp // disallow non-atomic comparison
-type storedError struct{ Value error }
-
-func wrapError(v error) storedError {
- return storedError{v}
+ v Value
}
-func unwrapError(v storedError) error {
- return v.Value
-}
+var _zeroError error
// NewError creates a new Error.
func NewError(v error) *Error {
x := &Error{}
- if v != nil {
+ if v != _zeroError {
x.Store(v)
}
return x
@@ -46,16 +42,10 @@
// Load atomically loads the wrapped error.
func (x *Error) Load() error {
- v := x.v.Load()
- if v == nil {
- return nil
- }
- return unwrapError(v.(storedError))
+ return unpackError(x.v.Load())
}
// Store atomically stores the passed error.
-//
-// NOTE: This will cause an allocation.
func (x *Error) Store(v error) {
- x.v.Store(wrapError(v))
+ x.v.Store(packError(v))
}
diff --git a/error_ext.go b/error_ext.go
new file mode 100644
index 0000000..ffe0be2
--- /dev/null
+++ b/error_ext.go
@@ -0,0 +1,39 @@
+// Copyright (c) 2020 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.
+
+package atomic
+
+// atomic.Value panics on nil inputs, or if the underlying type changes.
+// Stabilize by always storing a custom struct that we control.
+
+//go:generate bin/gen-atomicwrapper -name=Error -type=error -wrapped=Value -pack=packError -unpack=unpackError -file=error.go
+
+type packedError struct{ Value error }
+
+func packError(v error) interface{} {
+ return packedError{v}
+}
+
+func unpackError(v interface{}) error {
+ if err, ok := v.(packedError); ok {
+ return err.Value
+ }
+ return nil
+}
diff --git a/float64.go b/float64.go
new file mode 100644
index 0000000..fb33e90
--- /dev/null
+++ b/float64.go
@@ -0,0 +1,76 @@
+// @generated Code generated by gen-atomicwrapper.
+
+// Copyright (c) 2020 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.
+
+package atomic
+
+import (
+ "encoding/json"
+ "math"
+)
+
+// Float64 is an atomic type-safe wrapper for float64 values.
+type Float64 struct {
+ nocmp // disallow non-atomic comparison
+
+ v Uint64
+}
+
+var _zeroFloat64 float64
+
+// NewFloat64 creates a new Float64.
+func NewFloat64(v float64) *Float64 {
+ x := &Float64{}
+ if v != _zeroFloat64 {
+ x.Store(v)
+ }
+ return x
+}
+
+// Load atomically loads the wrapped float64.
+func (x *Float64) Load() float64 {
+ return math.Float64frombits(x.v.Load())
+}
+
+// Store atomically stores the passed float64.
+func (x *Float64) Store(v float64) {
+ x.v.Store(math.Float64bits(v))
+}
+
+// CAS is an atomic compare-and-swap for float64 values.
+func (x *Float64) CAS(o, n float64) bool {
+ return x.v.CAS(math.Float64bits(o), math.Float64bits(n))
+}
+
+// MarshalJSON encodes the wrapped float64 into JSON.
+func (x *Float64) MarshalJSON() ([]byte, error) {
+ return json.Marshal(x.Load())
+}
+
+// UnmarshalJSON decodes a float64 from JSON.
+func (x *Float64) UnmarshalJSON(b []byte) error {
+ var v float64
+ if err := json.Unmarshal(b, &v); err != nil {
+ return err
+ }
+ x.Store(v)
+ return nil
+}
diff --git a/float64_ext.go b/float64_ext.go
new file mode 100644
index 0000000..927b1ad
--- /dev/null
+++ b/float64_ext.go
@@ -0,0 +1,47 @@
+// Copyright (c) 2020 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.
+
+package atomic
+
+import "strconv"
+
+//go:generate bin/gen-atomicwrapper -name=Float64 -type=float64 -wrapped=Uint64 -pack=math.Float64bits -unpack=math.Float64frombits -cas -json -imports math -file=float64.go
+
+// Add atomically adds to the wrapped float64 and returns the new value.
+func (f *Float64) Add(s float64) float64 {
+ for {
+ old := f.Load()
+ new := old + s
+ if f.CAS(old, new) {
+ return new
+ }
+ }
+}
+
+// Sub atomically subtracts from the wrapped float64 and returns the new value.
+func (f *Float64) Sub(s float64) float64 {
+ return f.Add(-s)
+}
+
+// String encodes the wrapped value as a string.
+func (f *Float64) String() string {
+ // 'g' is the behavior for floats with %v.
+ return strconv.FormatFloat(f.Load(), 'g', -1, 64)
+}
diff --git a/float64_test.go b/float64_test.go
new file mode 100644
index 0000000..bc04e77
--- /dev/null
+++ b/float64_test.go
@@ -0,0 +1,69 @@
+// Copyright (c) 2020 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.
+
+package atomic
+
+import (
+ "encoding/json"
+ "testing"
+
+ "github.com/stretchr/testify/assert"
+ "github.com/stretchr/testify/require"
+)
+
+func TestFloat64(t *testing.T) {
+ atom := NewFloat64(4.2)
+
+ require.Equal(t, float64(4.2), atom.Load(), "Load didn't work.")
+
+ require.True(t, atom.CAS(4.2, 0.5), "CAS didn't report a swap.")
+ require.Equal(t, float64(0.5), atom.Load(), "CAS didn't set the correct value.")
+ require.False(t, atom.CAS(0.0, 1.5), "CAS reported a swap.")
+
+ atom.Store(42.0)
+ require.Equal(t, float64(42.0), atom.Load(), "Store didn't set the correct value.")
+ require.Equal(t, float64(42.5), atom.Add(0.5), "Add didn't work.")
+ require.Equal(t, float64(42.0), atom.Sub(0.5), "Sub didn't work.")
+
+ t.Run("JSON/Marshal", func(t *testing.T) {
+ atom.Store(42.5)
+ bytes, err := json.Marshal(atom)
+ require.NoError(t, err, "json.Marshal errored unexpectedly.")
+ require.Equal(t, []byte("42.5"), bytes, "json.Marshal encoded the wrong bytes.")
+ })
+
+ t.Run("JSON/Unmarshal", func(t *testing.T) {
+ err := json.Unmarshal([]byte("40.5"), &atom)
+ require.NoError(t, err, "json.Unmarshal errored unexpectedly.")
+ require.Equal(t, float64(40.5), atom.Load(), "json.Unmarshal didn't set the correct value.")
+ })
+
+ t.Run("JSON/Unmarshal/Error", func(t *testing.T) {
+ err := json.Unmarshal([]byte("\"40.5\""), &atom)
+ require.Error(t, err, "json.Unmarshal didn't error as expected.")
+ assertErrorJSONUnmarshalType(t, err,
+ "json.Unmarshal failed with unexpected error %v, want UnmarshalTypeError.", err)
+ })
+
+ t.Run("String", func(t *testing.T) {
+ assert.Equal(t, "42.5", NewFloat64(42.5).String(),
+ "String() returned an unexpected value.")
+ })
+}
diff --git a/gen.go b/gen.go
index 03c8ac9..50d6b24 100644
--- a/gen.go
+++ b/gen.go
@@ -24,6 +24,3 @@
//go:generate bin/gen-atomicint -name=Int64 -wrapped=int64 -file=int64.go
//go:generate bin/gen-atomicint -name=Uint32 -wrapped=uint32 -unsigned -file=uint32.go
//go:generate bin/gen-atomicint -name=Uint64 -wrapped=uint64 -unsigned -file=uint64.go
-
-//go:generate bin/gen-valuewrapper -name=String -type=string -zero="" -file=string.go
-//go:generate bin/gen-valuewrapper -name=Error -type=error -zero=nil -file=error.go
diff --git a/internal/gen-atomicwrapper/main.go b/internal/gen-atomicwrapper/main.go
new file mode 100644
index 0000000..0bb180e
--- /dev/null
+++ b/internal/gen-atomicwrapper/main.go
@@ -0,0 +1,300 @@
+// Copyright (c) 2020 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.
+
+// gen-atomicwrapper generates wrapper types around other atomic types.
+//
+// It supports plugging in functions which convert the value inside the atomic
+// type to the user-facing value. For example,
+//
+// Given, atomic.Value and the functions,
+//
+// func packString(string) interface{}
+// func unpackString(interface{}) string
+//
+// We can run the following command:
+//
+// gen-atomicwrapper -name String -wrapped Value \
+// -type string -pack fromString -unpack tostring
+//
+// This wil generate approximately,
+//
+// type String struct{ v Value }
+//
+// func (s *String) Load() string {
+// return unpackString(v.Load())
+// }
+//
+// func (s *String) Store(s string) {
+// return s.v.Store(packString(s))
+// }
+//
+// The packing/unpacking logic allows the stored value to be different from
+// the user-facing value.
+//
+// Without -pack and -unpack, the output will be cast to the target type,
+// defaulting to the zero value.
+package main
+
+import (
+ "bytes"
+ "errors"
+ "flag"
+ "fmt"
+ "go/format"
+ "io"
+ "log"
+ "os"
+ "sort"
+ "strings"
+ "text/template"
+)
+
+func main() {
+ log.SetFlags(0)
+ if err := run(os.Args[1:]); err != nil {
+ log.Fatalf("%+v", err)
+ }
+}
+
+type stringList []string
+
+func (sl *stringList) String() string {
+ return strings.Join(*sl, ",")
+}
+
+func (sl *stringList) Set(s string) error {
+ for _, i := range strings.Split(s, ",") {
+ *sl = append(*sl, strings.TrimSpace(i))
+ }
+ return nil
+}
+
+func run(args []string) error {
+ var opts struct {
+ Name string
+ Wrapped string
+ Type string
+
+ Imports stringList
+ Pack, Unpack string
+
+ CAS bool
+ Swap bool
+ JSON bool
+
+ File string
+ }
+
+ flag := flag.NewFlagSet("gen-atomicwrapper", flag.ContinueOnError)
+
+ // Required flags
+ flag.StringVar(&opts.Name, "name", "",
+ "name of the generated type (e.g. Duration)")
+ flag.StringVar(&opts.Wrapped, "wrapped", "",
+ "name of the wrapped atomic (e.g. Int64)")
+ flag.StringVar(&opts.Type, "type", "",
+ "name of the type exposed by the atomic (e.g. time.Duration)")
+
+ // Optional flags
+ flag.Var(&opts.Imports, "imports",
+ "comma separated list of imports to add")
+ flag.StringVar(&opts.Pack, "pack", "",
+ "function to transform values with before storage")
+ flag.StringVar(&opts.Unpack, "unpack", "",
+ "function to reverse packing on loading")
+ flag.StringVar(&opts.File, "file", "",
+ "output file path (default: stdout)")
+
+ // Switches for individual methods. Underlying atomics must support
+ // these.
+ flag.BoolVar(&opts.CAS, "cas", false,
+ "generate a `CAS(old, new) bool` method; requires -pack")
+ flag.BoolVar(&opts.Swap, "swap", false,
+ "generate a `Swap(new) old` method; requires -pack and -unpack")
+ flag.BoolVar(&opts.JSON, "json", false,
+ "generate `MarshalJSON/UnmarshJSON` methods")
+
+ if err := flag.Parse(args); err != nil {
+ return err
+ }
+
+ if len(opts.Name) == 0 || len(opts.Wrapped) == 0 || len(opts.Type) == 0 {
+ return errors.New("flags -name, -wrapped, and -type are required")
+ }
+
+ if (len(opts.Pack) == 0) != (len(opts.Unpack) == 0) {
+ return errors.New("either both, or neither of -pack and -unpack must be specified")
+ }
+
+ if opts.CAS && len(opts.Pack) == 0 {
+ return errors.New("flag -cas requires -pack")
+ }
+
+ if opts.Swap && len(opts.Pack) == 0 {
+ return errors.New("flag -swap requires -pack and -unpack")
+ }
+
+ var w io.Writer = os.Stdout
+ if file := opts.File; len(file) > 0 {
+ f, err := os.Create(file)
+ if err != nil {
+ return fmt.Errorf("create %q: %v", file, err)
+ }
+ defer f.Close()
+
+ w = f
+ }
+
+ // Import encoding/json if needed.
+ if opts.JSON {
+ found := false
+ for _, imp := range opts.Imports {
+ if imp == "encoding/json" {
+ found = true
+ break
+ }
+ }
+
+ if !found {
+ opts.Imports = append(opts.Imports, "encoding/json")
+ }
+ }
+
+ sort.Strings([]string(opts.Imports))
+
+ var buff bytes.Buffer
+ if err := _tmpl.Execute(&buff, opts); err != nil {
+ return fmt.Errorf("render template: %v", err)
+ }
+
+ bs, err := format.Source(buff.Bytes())
+ if err != nil {
+ return fmt.Errorf("reformat source: %v", err)
+ }
+
+ _, err = w.Write(bs)
+ return err
+}
+
+var _tmpl = template.Must(template.New("int.go").Parse(`// @generated Code generated by gen-atomicwrapper.
+
+// Copyright (c) 2020 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.
+
+package atomic
+
+{{ with .Imports }}
+import (
+ {{ range . -}}
+ {{ printf "%q" . }}
+ {{ end }}
+)
+{{ end }}
+
+// {{ .Name }} is an atomic type-safe wrapper for {{ .Type }} values.
+type {{ .Name }} struct{
+ nocmp // disallow non-atomic comparison
+
+ v {{ .Wrapped }}
+}
+
+var _zero{{ .Name }} {{ .Type }}
+
+
+// New{{ .Name }} creates a new {{ .Name }}.
+func New{{ .Name}}(v {{ .Type }}) *{{ .Name }} {
+ x := &{{ .Name }}{}
+ if v != _zero{{ .Name }} {
+ x.Store(v)
+ }
+ return x
+}
+
+// Load atomically loads the wrapped {{ .Type }}.
+func (x *{{ .Name }}) Load() {{ .Type }} {
+ {{ if .Unpack -}}
+ return {{ .Unpack }}(x.v.Load())
+ {{- else -}}
+ if v := x.v.Load(); v != nil {
+ return v.({{ .Type }})
+ }
+ return _zero{{ .Name }}
+ {{- end }}
+}
+
+// Store atomically stores the passed {{ .Type }}.
+func (x *{{ .Name }}) Store(v {{ .Type }}) {
+ {{ if .Pack -}}
+ x.v.Store({{ .Pack }}(v))
+ {{- else -}}
+ x.v.Store(v)
+ {{- end }}
+}
+
+{{ if .CAS -}}
+ // CAS is an atomic compare-and-swap for {{ .Type }} values.
+ func (x *{{ .Name }}) CAS(o, n {{ .Type }}) bool {
+ return x.v.CAS({{ .Pack }}(o), {{ .Pack }}(n))
+ }
+{{- end }}
+
+{{ if .Swap -}}
+ // Swap atomically stores the given {{ .Type }} and returns the old
+ // value.
+ func (x *{{ .Name }}) Swap(o {{ .Type }}) {{ .Type }} {
+ return {{ .Unpack }}(x.v.Swap({{ .Pack }}(o)))
+ }
+{{- end }}
+
+{{ if .JSON -}}
+ // MarshalJSON encodes the wrapped {{ .Type }} into JSON.
+ func (x *{{ .Name }}) MarshalJSON() ([]byte, error) {
+ return json.Marshal(x.Load())
+ }
+
+ // UnmarshalJSON decodes a {{ .Type }} from JSON.
+ func (x *{{ .Name }}) UnmarshalJSON(b []byte) error {
+ var v {{ .Type }}
+ if err := json.Unmarshal(b, &v); err != nil {
+ return err
+ }
+ x.Store(v)
+ return nil
+ }
+{{- end }}
+
+`))
diff --git a/internal/gen-valuewrapper/main.go b/internal/gen-valuewrapper/main.go
deleted file mode 100644
index 520701e..0000000
--- a/internal/gen-valuewrapper/main.go
+++ /dev/null
@@ -1,173 +0,0 @@
-// Copyright (c) 2020 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.
-
-package main
-
-import (
- "bytes"
- "errors"
- "flag"
- "fmt"
- "go/format"
- "io"
- "log"
- "os"
- "text/template"
-)
-
-func main() {
- log.SetFlags(0)
- if err := run(os.Args[1:]); err != nil {
- log.Fatalf("%+v", err)
- }
-}
-
-func run(args []string) error {
- var opts struct {
- Name string
- Type string
- Zero string
- File string
- }
-
- flag := flag.NewFlagSet("gen-atomicint", flag.ContinueOnError)
-
- flag.StringVar(&opts.Name, "name", "", "name of the generated type (e.g. Int32)")
- flag.StringVar(&opts.Type, "type", "", "name of the wrapped type (e.g. int32)")
- flag.StringVar(&opts.Zero, "zero", "", "zero value of the wrapped type (e.g. nil)")
- flag.StringVar(&opts.File, "file", "", "output file path (default: stdout)")
-
- if err := flag.Parse(args); err != nil {
- return err
- }
-
- if len(opts.Name) == 0 || len(opts.Type) == 0 || len(opts.Zero) == 0 {
- return errors.New("flags -name, -type, and -zero are required")
- }
-
- var w io.Writer = os.Stdout
- if file := opts.File; len(file) > 0 {
- f, err := os.Create(file)
- if err != nil {
- return fmt.Errorf("create %q: %v", file, err)
- }
- defer f.Close()
-
- w = f
- }
-
- data := struct {
- Name string
- Type string
- Zero string
- Nillable bool
- }{
- Name: opts.Name,
- Type: opts.Type,
- Zero: opts.Zero,
- Nillable: opts.Zero == "nil",
- }
-
- var buff bytes.Buffer
- if err := _tmpl.Execute(&buff, data); err != nil {
- return fmt.Errorf("render template: %v", err)
- }
-
- bs, err := format.Source(buff.Bytes())
- if err != nil {
- return fmt.Errorf("reformat source: %v", err)
- }
-
- _, err = w.Write(bs)
- return err
-}
-
-var _tmpl = template.Must(template.New("int.go").Parse(`// @generated Code generated by gen-valuewrapper.
-
-// Copyright (c) 2020 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.
-
-package atomic
-
-// {{ .Name }} is an atomic type-safe wrapper for {{ .Type }} values.
-type {{ .Name }} struct{ v Value }
-
-{{/* atomic.Value panics for nil values. Generate a wrapper for these types. */}}
-{{ $stored := .Type }}
-{{ $wrap := .Type }}
-{{ $unwrap := .Type }}
-{{ if .Nillable -}}
- {{ $stored = printf "stored%s" .Name }}
- {{ $wrap = printf "wrap%s" .Name }}
- {{ $unwrap = printf "unwrap%s" .Name }}
-
- type {{ $stored }} struct{ Value {{ .Type }} }
-
- func {{ $wrap }}(v {{ .Type }}) {{ $stored }} {
- return {{ $stored }}{v}
- }
-
- func {{ $unwrap }}(v {{ $stored }}) {{ .Type }} {
- return v.Value
- }
-{{- end }}
-
-// New{{ .Name }} creates a new {{ .Name }}.
-func New{{ .Name }}(v {{ .Type }}) *{{ .Name }} {
- x := &{{ .Name }}{}
- if v != {{ .Zero }} {
- x.Store(v)
- }
- return x
-}
-
-// Load atomically loads the wrapped {{ .Type }}.
-func (x *{{ .Name }}) Load() {{ .Type }} {
- v := x.v.Load()
- if v == nil {
- return {{ .Zero }}
- }
- return {{ $unwrap }}(v.({{ $stored }}))
-}
-
-// Store atomically stores the passed {{ .Type }}.
-//
-// NOTE: This will cause an allocation.
-func (x *{{ .Name }}) Store(v {{ .Type }}) {
- x.v.Store({{ $wrap }}(v))
-}
-`))
diff --git a/string.go b/string.go
index 8829c48..8e3ac35 100644
--- a/string.go
+++ b/string.go
@@ -1,4 +1,4 @@
-// @generated Code generated by gen-valuewrapper.
+// @generated Code generated by gen-atomicwrapper.
// Copyright (c) 2020 Uber Technologies, Inc.
//
@@ -23,12 +23,18 @@
package atomic
// String is an atomic type-safe wrapper for string values.
-type String struct{ v Value }
+type String struct {
+ nocmp // disallow non-atomic comparison
+
+ v Value
+}
+
+var _zeroString string
// NewString creates a new String.
func NewString(v string) *String {
x := &String{}
- if v != "" {
+ if v != _zeroString {
x.Store(v)
}
return x
@@ -36,16 +42,13 @@
// Load atomically loads the wrapped string.
func (x *String) Load() string {
- v := x.v.Load()
- if v == nil {
- return ""
+ if v := x.v.Load(); v != nil {
+ return v.(string)
}
- return string(v.(string))
+ return _zeroString
}
// Store atomically stores the passed string.
-//
-// NOTE: This will cause an allocation.
func (x *String) Store(v string) {
- x.v.Store(string(v))
+ x.v.Store(v)
}
diff --git a/string_ext.go b/string_ext.go
index a346358..3a95582 100644
--- a/string_ext.go
+++ b/string_ext.go
@@ -20,6 +20,8 @@
package atomic
+//go:generate bin/gen-atomicwrapper -name=String -type=string -wrapped=Value -file=string.go
+
// String returns the wrapped value.
func (s *String) String() string {
return s.Load()
diff --git a/value.go b/value.go
new file mode 100644
index 0000000..5c32903
--- /dev/null
+++ b/value.go
@@ -0,0 +1,30 @@
+// Copyright (c) 2020 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.
+
+package atomic
+
+import "sync/atomic"
+
+// Value shadows the type of the same name from sync/atomic
+// https://godoc.org/sync/atomic#Value
+type Value struct {
+ nocmp // disallow non-atomic comparison
+ atomic.Value
+}
diff --git a/value_test.go b/value_test.go
new file mode 100644
index 0000000..bb9f301
--- /dev/null
+++ b/value_test.go
@@ -0,0 +1,40 @@
+// Copyright (c) 2020 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.
+
+package atomic
+
+import (
+ "testing"
+
+ "github.com/stretchr/testify/assert"
+)
+
+func TestValue(t *testing.T) {
+ var v Value
+ assert.Nil(t, v.Load(), "initial Value is not nil")
+
+ v.Store(42)
+ assert.Equal(t, 42, v.Load())
+
+ v.Store(84)
+ assert.Equal(t, 84, v.Load())
+
+ assert.Panics(t, func() { v.Store("foo") })
+}
