1 // Copyright 2017, OpenCensus Authors 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); 4 // you may not use this file except in compliance with the License. 5 // You may obtain a copy of the License at 6 // 7 // http://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 // See the License for the specific language governing permissions and 13 // limitations under the License. 14 // 15 16 package view 17 18 import "time" 19 20 // AggType represents the type of aggregation function used on a View. 21 type AggType int 22 23 // All available aggregation types. 24 const ( 25 AggTypeNone AggType = iota // no aggregation; reserved for future use. 26 AggTypeCount // the count aggregation, see Count. 27 AggTypeSum // the sum aggregation, see Sum. 28 AggTypeDistribution // the distribution aggregation, see Distribution. 29 AggTypeLastValue // the last value aggregation, see LastValue. 30 ) 31 32 func (t AggType) String() string { 33 return aggTypeName[t] 34 } 35 36 var aggTypeName = map[AggType]string{ 37 AggTypeNone: "None", 38 AggTypeCount: "Count", 39 AggTypeSum: "Sum", 40 AggTypeDistribution: "Distribution", 41 AggTypeLastValue: "LastValue", 42 } 43 44 // Aggregation represents a data aggregation method. Use one of the functions: 45 // Count, Sum, or Distribution to construct an Aggregation. 46 type Aggregation struct { 47 Type AggType // Type is the AggType of this Aggregation. 48 Buckets []float64 // Buckets are the bucket endpoints if this Aggregation represents a distribution, see Distribution. 49 50 newData func(time.Time) AggregationData 51 } 52 53 var ( 54 aggCount = &Aggregation{ 55 Type: AggTypeCount, 56 newData: func(t time.Time) AggregationData { 57 return &CountData{Start: t} 58 }, 59 } 60 aggSum = &Aggregation{ 61 Type: AggTypeSum, 62 newData: func(t time.Time) AggregationData { 63 return &SumData{Start: t} 64 }, 65 } 66 ) 67 68 // Count indicates that data collected and aggregated 69 // with this method will be turned into a count value. 70 // For example, total number of accepted requests can be 71 // aggregated by using Count. 72 func Count() *Aggregation { 73 return aggCount 74 } 75 76 // Sum indicates that data collected and aggregated 77 // with this method will be summed up. 78 // For example, accumulated request bytes can be aggregated by using 79 // Sum. 80 func Sum() *Aggregation { 81 return aggSum 82 } 83 84 // Distribution indicates that the desired aggregation is 85 // a histogram distribution. 86 // 87 // A distribution aggregation may contain a histogram of the values in the 88 // population. The bucket boundaries for that histogram are described 89 // by the bounds. This defines len(bounds)+1 buckets. 90 // 91 // If len(bounds) >= 2 then the boundaries for bucket index i are: 92 // 93 // [-infinity, bounds[i]) for i = 0 94 // [bounds[i-1], bounds[i]) for 0 < i < length 95 // [bounds[i-1], +infinity) for i = length 96 // 97 // If len(bounds) is 0 then there is no histogram associated with the 98 // distribution. There will be a single bucket with boundaries 99 // (-infinity, +infinity). 100 // 101 // If len(bounds) is 1 then there is no finite buckets, and that single 102 // element is the common boundary of the overflow and underflow buckets. 103 func Distribution(bounds ...float64) *Aggregation { 104 agg := &Aggregation{ 105 Type: AggTypeDistribution, 106 Buckets: bounds, 107 } 108 agg.newData = func(t time.Time) AggregationData { 109 return newDistributionData(agg, t) 110 } 111 return agg 112 } 113 114 // LastValue only reports the last value recorded using this 115 // aggregation. All other measurements will be dropped. 116 func LastValue() *Aggregation { 117 return &Aggregation{ 118 Type: AggTypeLastValue, 119 newData: func(_ time.Time) AggregationData { 120 return &LastValueData{} 121 }, 122 } 123 } 124