forked from TrueCloudLab/distribution
109 lines
3.1 KiB
Go
109 lines
3.1 KiB
Go
// Copyright 2017, OpenCensus Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//
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package stats
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import (
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"sync"
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"sync/atomic"
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)
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// Measure represents a single numeric value to be tracked and recorded.
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// For example, latency, request bytes, and response bytes could be measures
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// to collect from a server.
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//
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// Measures by themselves have no outside effects. In order to be exported,
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// the measure needs to be used in a View. If no Views are defined over a
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// measure, there is very little cost in recording it.
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type Measure interface {
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// Name returns the name of this measure.
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//
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// Measure names are globally unique (among all libraries linked into your program).
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// We recommend prefixing the measure name with a domain name relevant to your
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// project or application.
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//
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// Measure names are never sent over the wire or exported to backends.
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// They are only used to create Views.
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Name() string
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// Description returns the human-readable description of this measure.
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Description() string
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// Unit returns the units for the values this measure takes on.
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//
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// Units are encoded according to the case-sensitive abbreviations from the
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// Unified Code for Units of Measure: http://unitsofmeasure.org/ucum.html
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Unit() string
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}
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// measureDescriptor is the untyped descriptor associated with each measure.
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// Int64Measure and Float64Measure wrap measureDescriptor to provide typed
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// recording APIs.
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// Two Measures with the same name will have the same measureDescriptor.
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type measureDescriptor struct {
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subs int32 // access atomically
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name string
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description string
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unit string
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}
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func (m *measureDescriptor) subscribe() {
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atomic.StoreInt32(&m.subs, 1)
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}
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func (m *measureDescriptor) subscribed() bool {
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return atomic.LoadInt32(&m.subs) == 1
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}
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var (
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mu sync.RWMutex
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measures = make(map[string]*measureDescriptor)
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)
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func registerMeasureHandle(name, desc, unit string) *measureDescriptor {
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mu.Lock()
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defer mu.Unlock()
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if stored, ok := measures[name]; ok {
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return stored
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}
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m := &measureDescriptor{
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name: name,
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description: desc,
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unit: unit,
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}
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measures[name] = m
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return m
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}
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// Measurement is the numeric value measured when recording stats. Each measure
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// provides methods to create measurements of their kind. For example, Int64Measure
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// provides M to convert an int64 into a measurement.
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type Measurement struct {
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v float64
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m Measure
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desc *measureDescriptor
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}
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// Value returns the value of the Measurement as a float64.
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func (m Measurement) Value() float64 {
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return m.v
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}
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// Measure returns the Measure from which this Measurement was created.
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func (m Measurement) Measure() Measure {
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return m.m
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}
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