Provide atomic type for float32 (#107)

float32.go

@@ -0,0 +1,77 @@
+// @generated Code generated by gen-atomicwrapper.
+
+// Copyright (c) 2020-2022 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.
+
+package atomic
+
+import (
+	"encoding/json"
+	"math"
+)
+
+// Float32 is an atomic type-safe wrapper for float32 values.
+type Float32 struct {
+	_ nocmp // disallow non-atomic comparison
+
+	v Uint32
+}
+
+var _zeroFloat32 float32
+
+// NewFloat32 creates a new Float32.
+func NewFloat32(val float32) *Float32 {
+	x := &Float32{}
+	if val != _zeroFloat32 {
+		x.Store(val)
+	}
+	return x
+}
+
+// Load atomically loads the wrapped float32.
+func (x *Float32) Load() float32 {
+	return math.Float32frombits(x.v.Load())
+}
+
+// Store atomically stores the passed float32.
+func (x *Float32) Store(val float32) {
+	x.v.Store(math.Float32bits(val))
+}
+
+// Swap atomically stores the given float32 and returns the old
+// value.
+func (x *Float32) Swap(val float32) (old float32) {
+	return math.Float32frombits(x.v.Swap(math.Float32bits(val)))
+}
+
+// MarshalJSON encodes the wrapped float32 into JSON.
+func (x *Float32) MarshalJSON() ([]byte, error) {
+	return json.Marshal(x.Load())
+}
+
+// UnmarshalJSON decodes a float32 from JSON.
+func (x *Float32) UnmarshalJSON(b []byte) error {
+	var v float32
+	if err := json.Unmarshal(b, &v); err != nil {
+		return err
+	}
+	x.Store(v)
+	return nil
+}

float32_ext.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 (
+	"math"
+	"strconv"
+)
+
+//go:generate bin/gen-atomicwrapper -name=Float32 -type=float32 -wrapped=Uint32 -pack=math.Float32bits -unpack=math.Float32frombits -swap -json -imports math -file=float32.go
+
+// Add atomically adds to the wrapped float32 and returns the new value.
+func (f *Float32) Add(delta float32) float32 {
+	for {
+		old := f.Load()
+		new := old + delta
+		if f.CAS(old, new) {
+			return new
+		}
+	}
+}
+
+// Sub atomically subtracts from the wrapped float32 and returns the new value.
+func (f *Float32) Sub(delta float32) float32 {
+	return f.Add(-delta)
+}
+
+// CAS is an atomic compare-and-swap for float32 values.
+//
+// Note: CAS handles NaN incorrectly. NaN != NaN using Go's inbuilt operators
+// but CAS allows a stored NaN to compare equal to a passed in NaN.
+// This avoids typical CAS loops from blocking forever, e.g.,
+//
+//   for {
+//     old := atom.Load()
+//     new = f(old)
+//     if atom.CAS(old, new) {
+//       break
+//     }
+//   }
+//
+// If CAS did not match NaN to match, then the above would loop forever.
+func (f *Float32) CAS(old, new float32) (swapped bool) {
+	return f.v.CAS(math.Float32bits(old), math.Float32bits(new))
+}
+
+// String encodes the wrapped value as a string.
+func (f *Float32) String() string {
+	// 'g' is the behavior for floats with %v.
+	return strconv.FormatFloat(float64(f.Load()), 'g', -1, 32)
+}

float32_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"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestFloat32(t *testing.T) {
+	atom := NewFloat32(4.2)
+
+	require.Equal(t, float32(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, float32(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, float32(42.0), atom.Load(), "Store didn't set the correct value.")
+	require.Equal(t, float32(42.5), atom.Add(0.5), "Add didn't work.")
+	require.Equal(t, float32(42.0), atom.Sub(0.5), "Sub didn't work.")
+
+	require.Equal(t, float32(42.0), atom.Swap(45.0), "Swap didn't return the old value.")
+	require.Equal(t, float32(45.0), atom.Load(), "Swap didn't set the correct value.")
+
+	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, float32(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", NewFloat32(42.5).String(),
+			"String() returned an unexpected value.")
+	})
+}