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70 lines
2.4 KiB
70 lines
2.4 KiB
3 years ago
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// Copyright (c) 2020 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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// Note: CAS handles NaN incorrectly. NaN != NaN using Go's inbuilt operators
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// but CAS allows a stored NaN to compare equal to a passed in NaN.
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// This avoids typical CAS 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.CAS(old, new) {
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// break
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// }
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// }
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//
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// If CAS did not match NaN to match, then the above would loop forever.
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func (f *Float64) CAS(old, new float64) (swapped bool) {
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return f.v.CAS(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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