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abool.go
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abool.go
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// The MIT License (MIT)
//
// Copyright (c) 2016 Tevin Zhang
//
// Source: https://github.com/tevino/abool/
//
// 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 abool provides atomic Boolean type for cleaner code and
// better performance.
package abool
import "sync/atomic"
// New creates an AtomicBool with default set to false.
func New() *AtomicBool {
return new(AtomicBool)
}
// NewBool creates an AtomicBool with given default value.
func NewBool(ok bool) *AtomicBool {
ab := New()
if ok {
ab.Set()
}
return ab
}
// AtomicBool is an atomic Boolean.
// Its methods are all atomic, thus safe to be called by multiple goroutines simultaneously.
// Note: When embedding into a struct one should always use *AtomicBool to avoid copy.
type AtomicBool int32
// Set sets the Boolean to true.
func (ab *AtomicBool) Set() {
atomic.StoreInt32((*int32)(ab), 1)
}
// UnSet sets the Boolean to false.
func (ab *AtomicBool) UnSet() {
atomic.StoreInt32((*int32)(ab), 0)
}
// IsSet returns whether the Boolean is true.
func (ab *AtomicBool) IsSet() bool {
return atomic.LoadInt32((*int32)(ab))&1 == 1
}
// IsNotSet returns whether the Boolean is false.
func (ab *AtomicBool) IsNotSet() bool {
return !ab.IsSet()
}
// SetTo sets the boolean with given Boolean.
func (ab *AtomicBool) SetTo(yes bool) {
if yes {
atomic.StoreInt32((*int32)(ab), 1)
} else {
atomic.StoreInt32((*int32)(ab), 0)
}
}
// 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) {
var o, n int32
if old {
o = 1
}
if new {
n = 1
}
return atomic.CompareAndSwapInt32((*int32)(ab), o, n)
}