| // 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" |
| "strconv" |
| "sync/atomic" |
| ) |
| |
| // 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()) |
| } |