Files
atomic/duration.go
Prashant Varanasi 1505d282ac Fix Swap and CompareAndSwap for Value wrappers (#130)
* Regenerate code to update copyright end year to 2023

* Test behaviour of default values initialized in different ways

This adds repro tests for #126 and #129

* Fix Swap and CompareAndSwap for Value wrappers

Fixes #126, #129

All atomic types can be used without initialization, e.g., `var v
<AtomicType>`. This works fine for integer types as the initialized
value of 0 matches the default value for the user-facing type.  However,
for Value wrappers, they are initialized to `nil`, which is a value that
can't be set (triggers a panic) so the default value for the user-facing
type is forced to be stored as a different value. This leads to multiple
possible values representing the default user-facing type.

E.g., an `atomic.String` with value `""` may be represented by the
underlying atomic as either `nil`, or `""`. This causes issues when we
don't handle the `nil` value correctly, causing to panics in `Swap` and
incorrectly not swapping values in `CompareAndSwap`.

This change fixes the above issues by:
 * Requiring `pack` and `unpack` function in gen-atomicwrapper as the
   only place we weren't supplying them was for `String`, and the
   branching adds unnecessary complexity, especially with added `nil`
   handling.
 * Extending `CompareAndSwap` for `Value` wrappers to try an additional
   `CompareAndSwap(nil, <new>)` only if the original `CompareAndSwap`
   fails and the old value is the zero value.
2023-02-06 01:17:57 -08:00

90 lines
2.7 KiB
Go

// @generated Code generated by gen-atomicwrapper.
// Copyright (c) 2020-2023 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(val time.Duration) *Duration {
x := &Duration{}
if val != _zeroDuration {
x.Store(val)
}
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(val time.Duration) {
x.v.Store(int64(val))
}
// CAS is an atomic compare-and-swap for time.Duration values.
//
// Deprecated: Use CompareAndSwap.
func (x *Duration) CAS(old, new time.Duration) (swapped bool) {
return x.CompareAndSwap(old, new)
}
// CompareAndSwap is an atomic compare-and-swap for time.Duration values.
func (x *Duration) CompareAndSwap(old, new time.Duration) (swapped bool) {
return x.v.CompareAndSwap(int64(old), int64(new))
}
// Swap atomically stores the given time.Duration and returns the old
// value.
func (x *Duration) Swap(val time.Duration) (old time.Duration) {
return time.Duration(x.v.Swap(int64(val)))
}
// 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
}