1505d282ac
* 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.
73 lines
2.3 KiB
Go
73 lines
2.3 KiB
Go
// @generated Code generated by gen-atomicwrapper.
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// Copyright (c) 2020-2023 Uber Technologies, Inc.
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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// THE SOFTWARE.
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package atomic
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// String is an atomic type-safe wrapper for string values.
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type String struct {
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_ nocmp // disallow non-atomic comparison
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v Value
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}
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var _zeroString string
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// NewString creates a new String.
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func NewString(val string) *String {
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x := &String{}
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if val != _zeroString {
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x.Store(val)
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}
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return x
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}
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// Load atomically loads the wrapped string.
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func (x *String) Load() string {
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return unpackString(x.v.Load())
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}
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// Store atomically stores the passed string.
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func (x *String) Store(val string) {
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x.v.Store(packString(val))
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}
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// CompareAndSwap is an atomic compare-and-swap for string values.
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func (x *String) CompareAndSwap(old, new string) (swapped bool) {
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if x.v.CompareAndSwap(packString(old), packString(new)) {
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return true
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}
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if old == _zeroString {
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// If the old value is the empty value, then it's possible the
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// underlying Value hasn't been set and is nil, so retry with nil.
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return x.v.CompareAndSwap(nil, packString(new))
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}
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return false
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}
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// Swap atomically stores the given string and returns the old
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// value.
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func (x *String) Swap(val string) (old string) {
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return unpackString(x.v.Swap(packString(val)))
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}
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