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atomic.go
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atomic.go
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// Copyright 2023 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package metrics
import (
"math"
"sync/atomic"
)
// atomicFloat64 provides atomic storage for float64.
type atomicFloat64 struct {
v atomic.Uint64 // stores result of math.Float64bits
}
// get returns the current value stored in f.
func (f *atomicFloat64) get() float64 { return math.Float64frombits(f.v.Load()) }
// set stores v in f.
func (f *atomicFloat64) set(v float64) { f.v.Store(math.Float64bits(v)) }
// add atomically adds v to f.
func (f *atomicFloat64) add(v float64) {
// Use compare-and-swap to change the stored representation
// atomically from old value to old value + v.
for {
cur := f.v.Load()
next := math.Float64bits(math.Float64frombits(cur) + v)
if f.v.CompareAndSwap(cur, next) {
return
}
}
}