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.
55 lines
1.9 KiB
Go
55 lines
1.9 KiB
Go
// 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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//go:generate bin/gen-atomicwrapper -name=String -type=string -wrapped Value -pack packString -unpack unpackString -compareandswap -swap -file=string.go
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func packString(s string) interface{} {
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return s
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}
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func unpackString(v interface{}) string {
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if s, ok := v.(string); ok {
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return s
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}
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return ""
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}
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// String returns the wrapped value.
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func (s *String) String() string {
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return s.Load()
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}
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// MarshalText encodes the wrapped string into a textual form.
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//
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// This makes it encodable as JSON, YAML, XML, and more.
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func (s *String) MarshalText() ([]byte, error) {
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return []byte(s.Load()), nil
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}
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// UnmarshalText decodes text and replaces the wrapped string with it.
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//
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// This makes it decodable from JSON, YAML, XML, and more.
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func (s *String) UnmarshalText(b []byte) error {
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s.Store(string(b))
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return nil
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}
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