golang value 代码
文件路径：/src/runtime/metrics/value.go
/ Copyright 2020 The Go Authors. All rights reserved.
/ Use of this source code is governed by a BSD-style
/ license that can be found in the LICENSE file.
package metrics
import (
"math"
"unsafe"
)
/ ValueKind is a tag for a metric Value which indicates its type.
type ValueKind int
const (
/ KindBad indicates that the Value has no type and should not be used.
KindBad ValueKind = iota
/ KindUint64 indicates that the type of the Value is a uint64.
KindUint64
/ KindFloat64 indicates that the type of the Value is a float64.
KindFloat64
/ KindFloat64Histogram indicates that the type of the Value is a *Float64Histogram.
KindFloat64Histogram
)
/ Value represents a metric value returned by the runtime.
type Value struct {
kind ValueKind
scalar uint64 / contains scalar values for scalar Kinds.
pointer unsafe.Pointer / contains non-scalar values.
}
/ Kind returns the tag representing the kind of value this is.
func (v Value) Kind() ValueKind {
return v.kind
}
/ Uint64 returns the internal uint64 value for the metric.
/
/ If v.Kind() != KindUint64, this method panics.
func (v Value) Uint64() uint64 {
if v.kind != KindUint64 {
panic("called Uint64 on non-uint64 metric value")
}
return v.scalar
}
/ Float64 returns the internal float64 value for the metric.
/
/ If v.Kind() != KindFloat64, this method panics.
func (v Value) Float64() float64 {
if v.kind != KindFloat64 {
panic("called Float64 on non-float64 metric value")
}
return math.Float64frombits(v.scalar)
}
/ Float64Histogram returns the internal *Float64Histogram value for the metric.
/
/ If v.Kind() != KindFloat64Histogram, this method panics.
func (v Value) Float64Histogram() *Float64Histogram {
if v.kind != KindFloat64Histogram {
panic("called Float64Histogram on non-Float64Histogram metric value")
}
return (*Float64Histogram)(v.pointer)
}