d4bbbc828d
Adds CompareAndSwap and Swap methods to String, Error, and Value, implemented by making use of Value.CompareAndSwap and Value.Swap added in Go 1.17. Following that, add CompareAndSwap to all other types with "CAS" methods and deprecate CAS in favor of CompareAndSwap, since that's the convention the standard library chose for these in Go 1.19.
77 lines
2.7 KiB
Go
77 lines
2.7 KiB
Go
// Copyright (c) 2020-2022 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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import (
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"math"
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"strconv"
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)
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//go:generate bin/gen-atomicwrapper -name=Float64 -type=float64 -wrapped=Uint64 -pack=math.Float64bits -unpack=math.Float64frombits -swap -json -imports math -file=float64.go
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// Add atomically adds to the wrapped float64 and returns the new value.
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func (f *Float64) Add(delta float64) float64 {
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for {
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old := f.Load()
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new := old + delta
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if f.CAS(old, new) {
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return new
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}
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}
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}
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// Sub atomically subtracts from the wrapped float64 and returns the new value.
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func (f *Float64) Sub(delta float64) float64 {
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return f.Add(-delta)
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}
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// CAS is an atomic compare-and-swap for float64 values.
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//
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// Deprecated: Use CompareAndSwap
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func (f *Float64) CAS(old, new float64) (swapped bool) {
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return f.CompareAndSwap(old, new)
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}
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// CompareAndSwap is an atomic compare-and-swap for float64 values.
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//
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// Note: CompareAndSwap handles NaN incorrectly. NaN != NaN using Go's inbuilt operators
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// but CompareAndSwap allows a stored NaN to compare equal to a passed in NaN.
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// This avoids typical CompareAndSwap loops from blocking forever, e.g.,
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//
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// for {
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// old := atom.Load()
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// new = f(old)
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// if atom.CompareAndSwap(old, new) {
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// break
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// }
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// }
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//
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// If CompareAndSwap did not match NaN to match, then the above would loop forever.
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func (f *Float64) CompareAndSwap(old, new float64) (swapped bool) {
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return f.v.CompareAndSwap(math.Float64bits(old), math.Float64bits(new))
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}
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// String encodes the wrapped value as a string.
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func (f *Float64) String() string {
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// 'g' is the behavior for floats with %v.
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return strconv.FormatFloat(f.Load(), 'g', -1, 64)
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}
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