github.com/cockroachdb/pebble@v1.1.2/internal/base/metrics.go (about) 1 // Copyright 2022 The LevelDB-Go and Pebble Authors. All rights reserved. Use 2 // of this source code is governed by a BSD-style license that can be found in 3 // the LICENSE file. 4 5 package base 6 7 import "time" 8 9 // ThroughputMetric is used to measure the byte throughput of some component 10 // that performs work in a single-threaded manner. The throughput can be 11 // approximated by Bytes/(WorkDuration+IdleTime). The idle time is represented 12 // separately, so that the user of this metric could approximate the peak 13 // throughput as Bytes/WorkTime. The metric is designed to be cumulative (see 14 // Merge). 15 type ThroughputMetric struct { 16 // Bytes is the processes bytes by the component. 17 Bytes int64 18 // WorkDuration is the duration that the component spent doing work. 19 WorkDuration time.Duration 20 // IdleDuration is the duration that the component was idling, waiting for 21 // work. 22 IdleDuration time.Duration 23 } 24 25 // Merge accumulates the information from another throughput metric. 26 func (tm *ThroughputMetric) Merge(x ThroughputMetric) { 27 tm.Bytes += x.Bytes 28 tm.WorkDuration += x.WorkDuration 29 tm.IdleDuration += x.IdleDuration 30 } 31 32 // Subtract subtracts the information from another ThroughputMetric 33 func (tm *ThroughputMetric) Subtract(x ThroughputMetric) { 34 tm.Bytes -= x.Bytes 35 tm.WorkDuration -= x.WorkDuration 36 tm.IdleDuration -= x.IdleDuration 37 } 38 39 // PeakRate returns the approximate peak rate if there was no idling. 40 func (tm *ThroughputMetric) PeakRate() int64 { 41 if tm.Bytes == 0 { 42 return 0 43 } 44 return int64((float64(tm.Bytes) / float64(tm.WorkDuration)) * float64(time.Second)) 45 } 46 47 // Rate returns the observed rate. 48 func (tm *ThroughputMetric) Rate() int64 { 49 if tm.Bytes == 0 { 50 return 0 51 } 52 return int64((float64(tm.Bytes) / float64(tm.WorkDuration+tm.IdleDuration)) * 53 float64(time.Second)) 54 } 55 56 // Utilization returns a percent [0, 1.0] indicating the percent of time 57 // work was performed. 58 func (tm *ThroughputMetric) Utilization() float64 { 59 if tm.WorkDuration == 0 { 60 return 0 61 } 62 return float64(tm.WorkDuration) / float64(tm.WorkDuration+tm.IdleDuration) 63 } 64 65 // GaugeSampleMetric is used to measure a gauge value (e.g. queue length) by 66 // accumulating samples of that gauge. 67 type GaugeSampleMetric struct { 68 // The sum of all the samples. 69 sampleSum int64 70 // The number of samples. 71 count int64 72 } 73 74 // AddSample adds the given sample. 75 func (gsm *GaugeSampleMetric) AddSample(sample int64) { 76 gsm.sampleSum += sample 77 gsm.count++ 78 } 79 80 // Merge accumulates the information from another gauge metric. 81 func (gsm *GaugeSampleMetric) Merge(x GaugeSampleMetric) { 82 gsm.sampleSum += x.sampleSum 83 gsm.count += x.count 84 } 85 86 // Subtract subtracts the information from another gauge metric. 87 func (gsm *GaugeSampleMetric) Subtract(x GaugeSampleMetric) { 88 gsm.sampleSum -= x.sampleSum 89 gsm.count -= x.count 90 } 91 92 // Mean returns the mean value. 93 func (gsm *GaugeSampleMetric) Mean() float64 { 94 if gsm.count == 0 { 95 return 0 96 } 97 return float64(gsm.sampleSum) / float64(gsm.count) 98 }