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194 lines
6.0 KiB
Go
194 lines
6.0 KiB
Go
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// Copyright 2018, 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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package metricdata
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import (
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"time"
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)
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// Point is a single data point of a time series.
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type Point struct {
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// Time is the point in time that this point represents in a time series.
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Time time.Time
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// Value is the value of this point. Prefer using ReadValue to switching on
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// the value type, since new value types might be added.
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Value interface{}
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}
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//go:generate stringer -type ValueType
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// NewFloat64Point creates a new Point holding a float64 value.
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func NewFloat64Point(t time.Time, val float64) Point {
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return Point{
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Value: val,
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Time: t,
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}
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}
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// NewInt64Point creates a new Point holding an int64 value.
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func NewInt64Point(t time.Time, val int64) Point {
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return Point{
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Value: val,
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Time: t,
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}
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}
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// NewDistributionPoint creates a new Point holding a Distribution value.
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func NewDistributionPoint(t time.Time, val *Distribution) Point {
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return Point{
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Value: val,
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Time: t,
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}
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}
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// NewSummaryPoint creates a new Point holding a Summary value.
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func NewSummaryPoint(t time.Time, val *Summary) Point {
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return Point{
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Value: val,
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Time: t,
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}
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}
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// ValueVisitor allows reading the value of a point.
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type ValueVisitor interface {
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VisitFloat64Value(float64)
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VisitInt64Value(int64)
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VisitDistributionValue(*Distribution)
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VisitSummaryValue(*Summary)
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}
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// ReadValue accepts a ValueVisitor and calls the appropriate method with the
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// value of this point.
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// Consumers of Point should use this in preference to switching on the type
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// of the value directly, since new value types may be added.
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func (p Point) ReadValue(vv ValueVisitor) {
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switch v := p.Value.(type) {
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case int64:
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vv.VisitInt64Value(v)
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case float64:
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vv.VisitFloat64Value(v)
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case *Distribution:
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vv.VisitDistributionValue(v)
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case *Summary:
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vv.VisitSummaryValue(v)
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default:
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panic("unexpected value type")
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}
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}
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// Distribution contains summary statistics for a population of values. It
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// optionally contains a histogram representing the distribution of those
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// values across a set of buckets.
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type Distribution struct {
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// Count is the number of values in the population. Must be non-negative. This value
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// must equal the sum of the values in bucket_counts if a histogram is
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// provided.
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Count int64
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// Sum is the sum of the values in the population. If count is zero then this field
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// must be zero.
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Sum float64
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// SumOfSquaredDeviation is the sum of squared deviations from the mean of the values in the
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// population. For values x_i this is:
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//
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// Sum[i=1..n]((x_i - mean)^2)
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//
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// Knuth, "The Art of Computer Programming", Vol. 2, page 323, 3rd edition
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// describes Welford's method for accumulating this sum in one pass.
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//
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// If count is zero then this field must be zero.
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SumOfSquaredDeviation float64
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// BucketOptions describes the bounds of the histogram buckets in this
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// distribution.
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//
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// A Distribution may optionally contain a histogram of the values in the
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// population.
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//
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// If nil, there is no associated histogram.
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BucketOptions *BucketOptions
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// Bucket If the distribution does not have a histogram, then omit this field.
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// If there is a histogram, then the sum of the values in the Bucket counts
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// must equal the value in the count field of the distribution.
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Buckets []Bucket
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}
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// BucketOptions describes the bounds of the histogram buckets in this
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// distribution.
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type BucketOptions struct {
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// Bounds specifies a set of bucket upper bounds.
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// This defines len(bounds) + 1 (= N) buckets. The boundaries for bucket
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// index i are:
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//
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// [0, Bounds[i]) for i == 0
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// [Bounds[i-1], Bounds[i]) for 0 < i < N-1
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// [Bounds[i-1], +infinity) for i == N-1
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Bounds []float64
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}
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// Bucket represents a single bucket (value range) in a distribution.
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type Bucket struct {
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// Count is the number of values in each bucket of the histogram, as described in
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// bucket_bounds.
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Count int64
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// Exemplar associated with this bucket (if any).
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Exemplar *Exemplar
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}
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// Summary is a representation of percentiles.
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type Summary struct {
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// Count is the cumulative count (if available).
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Count int64
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// Sum is the cumulative sum of values (if available).
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Sum float64
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// HasCountAndSum is true if Count and Sum are available.
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HasCountAndSum bool
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// Snapshot represents percentiles calculated over an arbitrary time window.
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// The values in this struct can be reset at arbitrary unknown times, with
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// the requirement that all of them are reset at the same time.
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Snapshot Snapshot
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}
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// Snapshot represents percentiles over an arbitrary time.
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// The values in this struct can be reset at arbitrary unknown times, with
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// the requirement that all of them are reset at the same time.
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type Snapshot struct {
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// Count is the number of values in the snapshot. Optional since some systems don't
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// expose this. Set to 0 if not available.
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Count int64
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// Sum is the sum of values in the snapshot. Optional since some systems don't
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// expose this. If count is 0 then this field must be zero.
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Sum float64
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// Percentiles is a map from percentile (range (0-100.0]) to the value of
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// the percentile.
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Percentiles map[float64]float64
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}
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//go:generate stringer -type Type
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// Type is the overall type of metric, including its value type and whether it
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// represents a cumulative total (since the start time) or if it represents a
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// gauge value.
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type Type int
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// Metric types.
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const (
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TypeGaugeInt64 Type = iota
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TypeGaugeFloat64
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TypeGaugeDistribution
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TypeCumulativeInt64
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TypeCumulativeFloat64
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TypeCumulativeDistribution
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TypeSummary
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)
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