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Revert "Merge pull request #3 from barryz/add_flip_method" 

Due to a regression to `SetToIf` introduced by `Toggle`

This reverts commit d91eb651d5, reversing
changes made to 9b9efcf221.
This commit is contained in:
Tevin Zhang 2021-09-05 12:25:08 +08:00
parent 9f5df6da9f
commit fa0b8a912b
No known key found for this signature in database
GPG Key ID: EE7DA2A50F0960FB
3 changed files with 15 additions and 127 deletions
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33
README.md
View File

@ -20,7 +20,6 @@ cond.UnSet() // Sets to false
cond.IsNotSet() // Returns true
cond.SetTo(any) // Sets to whatever you want
cond.SetToIf(new, old) // Sets to `new` only if the Boolean matches the `old`, returns whether succeeded
cond.Toggle() // Inverts the boolean then returns the value before inverting
// embedding
@ -29,33 +28,27 @@ type Foo struct {
}
```
## Benchmark
## Benchmark:
- Go 1.14.3
- Linux 4.19.0
- Go 1.6.2
- OS X 10.11.4
- Intel CPU (to be specified)
```bash
goos: linux
goarch: amd64
```
# Read
BenchmarkMutexRead-4 86662128 14.2 ns/op
BenchmarkAtomicValueRead-4 1000000000 0.755 ns/op
BenchmarkAtomicBoolRead-4 1000000000 0.720 ns/op # <--- This package
BenchmarkMutexRead-4 100000000 21.0 ns/op
BenchmarkAtomicValueRead-4 200000000 6.30 ns/op
BenchmarkAtomicBoolRead-4 300000000 4.21 ns/op # <--- This package
# Write
BenchmarkMutexWrite-4 76237544 13.6 ns/op
BenchmarkAtomicValueWrite-4 79471124 14.9 ns/op
BenchmarkAtomicBoolWrite-4 178218270 6.73 ns/op # <--- This package
BenchmarkMutexWrite-4 100000000 21.6 ns/op
BenchmarkAtomicValueWrite-4 30000000 43.4 ns/op
BenchmarkAtomicBoolWrite-4 200000000 9.87 ns/op # <--- This package
# CAS
BenchmarkMutexCAS-4 29416574 34.7 ns/op
BenchmarkAtomicBoolCAS-4 171900002 7.14 ns/op # <--- This package
# Toggle
BenchmarkMutexToggle-4 35212117 34.5 ns/op
BenchmarkAtomicBoolToggle-4 169871972 7.02 ns/op # <--- This package
BenchmarkMutexCAS-4 30000000 44.9 ns/op
BenchmarkAtomicBoolCAS-4 100000000 11.7 ns/op # <--- This package
```
## Special thanks to contributors

7
bool.go
View File

@ -38,7 +38,7 @@ func (ab *AtomicBool) UnSet() {
// IsSet returns whether the Boolean is true.
func (ab *AtomicBool) IsSet() bool {
return atomic.LoadInt32((*int32)(ab))&1 == 1
return atomic.LoadInt32((*int32)(ab)) == 1
}
// IsNotSet returns whether the Boolean is false.
@ -55,11 +55,6 @@ func (ab *AtomicBool) SetTo(yes bool) {
}
}
// Toggle inverts the Boolean then returns the value before inverting.
func (ab *AtomicBool) Toggle() bool {
return atomic.AddInt32((*int32)(ab), 1)&1 == 0
}
// SetToIf sets the Boolean to new only if the Boolean matches the old.
// Returns whether the set was done.
func (ab *AtomicBool) SetToIf(old, new bool) (set bool) {

102
bool_test.go
View File

@ -2,7 +2,6 @@ package abool
import (
"encoding/json"
"math"
"sync"
"sync/atomic"
"testing"
@ -73,78 +72,10 @@ func TestSetTo(t *testing.T) {
}
}
func TestToggle(t *testing.T) {
t.Parallel()
v := New()
_ = v.Toggle()
if !v.IsSet() {
t.Fatal("AtomicBool.Toggle() to true failed")
}
prev := v.Toggle()
if v.IsSet() == prev {
t.Fatal("AtomicBool.Toggle() to false failed")
}
}
func TestToogleMultipleTimes(t *testing.T) {
t.Parallel()
v := New()
pre := !v.IsSet()
for i := 0; i < 100; i++ {
v.SetTo(false)
for j := 0; j < i; j++ {
pre = v.Toggle()
}
expected := i%2 != 0
if v.IsSet() != expected {
t.Fatalf("AtomicBool.Toogle() doesn't work after %d calls, expected: %v, got %v", i, expected, v.IsSet())
}
if pre == v.IsSet() {
t.Fatalf("AtomicBool.Toogle() returned wrong value at the %dth calls, expected: %v, got %v", i, !v.IsSet(), pre)
}
}
}
func TestToogleAfterOverflow(t *testing.T) {
t.Parallel()
var value int32 = math.MaxInt32
v := (*AtomicBool)(&value)
valueBeforeToggle := *(*int32)(v)
// test first toggle after overflow
v.Toggle()
expected := math.MaxInt32%2 == 0
if v.IsSet() != expected {
t.Fatalf("AtomicBool.Toogle() doesn't work after overflow, expected: %v, got %v", expected, v.IsSet())
}
// make sure overflow happened
var valueAfterToggle int32 = *(*int32)(v)
if valueAfterToggle >= valueBeforeToggle {
t.Fatalf("Overflow does not happen as expected, before %d, after: %d", valueBeforeToggle, valueAfterToggle)
}
// test second toggle after overflow
v.Toggle()
expected = !expected
if v.IsSet() != expected {
t.Fatalf("AtomicBool.Toogle() doesn't work after the second call after overflow, expected: %v, got %v", expected, v.IsSet())
}
}
func TestRace(t *testing.T) {
t.Parallel()
repeat := 10000
var wg sync.WaitGroup
wg.Add(repeat * 4)
wg.Add(repeat * 3)
v := New()
// Writer
@ -170,15 +101,6 @@ func TestRace(t *testing.T) {
wg.Done()
}
}()
// Reader And Writer
go func() {
for i := 0; i < repeat; i++ {
v.Toggle()
wg.Done()
}
}()
wg.Wait()
}
@ -257,7 +179,6 @@ func ExampleAtomicBool() {
cond.IsNotSet() // Returns true
cond.SetTo(any) // Sets to whatever you want
cond.SetToIf(new, old) // Sets to `new` only if the Boolean matches the `old`, returns whether succeeded
cond.Toggle() // Inverts the boolean then returns the value before inverting
}
// Benchmark Read
@ -342,24 +263,3 @@ func BenchmarkAtomicBoolCAS(b *testing.B) {
v.SetToIf(false, true)
}
}
// Benchmark toggle
func BenchmarkMutexToggle(b *testing.B) {
var m sync.RWMutex
var v bool
b.ResetTimer()
for i := 0; i < b.N; i++ {
m.Lock()
v = !v
m.Unlock()
}
}
func BenchmarkAtomicBoolToggle(b *testing.B) {
v := New()
b.ResetTimer()
for i := 0; i < b.N; i++ {
v.Toggle()
}
}