1 // Copyright (c) 2020-2022 Uber Technologies, Inc. 2 // 3 // Permission is hereby granted, free of charge, to any person obtaining a copy 4 // of this software and associated documentation files (the "Software"), to deal 5 // in the Software without restriction, including without limitation the rights 6 // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 7 // copies of the Software, and to permit persons to whom the Software is 8 // furnished to do so, subject to the following conditions: 9 // 10 // The above copyright notice and this permission notice shall be included in 11 // all copies or substantial portions of the Software. 12 // 13 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 14 // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 15 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 16 // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 17 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 18 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN 19 // THE SOFTWARE. 20 21 package atomic 22 23 import ( 24 "math" 25 "strconv" 26 ) 27 28 //go:generate bin/gen-atomicwrapper -name=Float32 -type=float32 -wrapped=Uint32 -pack=math.Float32bits -unpack=math.Float32frombits -swap -json -imports math -file=float32.go 29 30 // Add atomically adds to the wrapped float32 and returns the new value. 31 func (f *Float32) Add(delta float32) float32 { 32 for { 33 old := f.Load() 34 new := old + delta 35 if f.CAS(old, new) { 36 return new 37 } 38 } 39 } 40 41 // Sub atomically subtracts from the wrapped float32 and returns the new value. 42 func (f *Float32) Sub(delta float32) float32 { 43 return f.Add(-delta) 44 } 45 46 // CAS is an atomic compare-and-swap for float32 values. 47 // 48 // Deprecated: Use CompareAndSwap 49 func (f *Float32) CAS(old, new float32) (swapped bool) { 50 return f.CompareAndSwap(old, new) 51 } 52 53 // CompareAndSwap is an atomic compare-and-swap for float32 values. 54 // 55 // Note: CompareAndSwap handles NaN incorrectly. NaN != NaN using Go's inbuilt operators 56 // but CompareAndSwap allows a stored NaN to compare equal to a passed in NaN. 57 // This avoids typical CompareAndSwap loops from blocking forever, e.g., 58 // 59 // for { 60 // old := atom.Load() 61 // new = f(old) 62 // if atom.CompareAndSwap(old, new) { 63 // break 64 // } 65 // } 66 // 67 // If CompareAndSwap did not match NaN to match, then the above would loop forever. 68 func (f *Float32) CompareAndSwap(old, new float32) (swapped bool) { 69 return f.v.CompareAndSwap(math.Float32bits(old), math.Float32bits(new)) 70 } 71 72 // String encodes the wrapped value as a string. 73 func (f *Float32) String() string { 74 // 'g' is the behavior for floats with %v. 75 return strconv.FormatFloat(float64(f.Load()), 'g', -1, 32) 76 } 77