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Remove simulation.go

pull/1/head
Stephanie Gredell 7 months ago
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294e78c7e6
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1 changed files with 0 additions and 277 deletions
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  1. 277
      internals/design/simulation.go

277
internals/design/simulation.go
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@ -1,277 +0,0 @@
package simulation
import (
"math"
)
type LoadBalancerSpec struct {
Capacity float64
BaseLatency int
Cost int
}
type WebServerSmall struct {
Capacity int
BaseLatency int
PenaltyPerRPS float64
Cost int
}
type WebServerMedium struct {
Capacity int
BaseLatency int
PenaltyPerRPS float64
Cost int
}
type CacheStandard struct {
Capacity int
BaseLatency int
PenaltyPer10RPS float64
HitRates map[string]float64
Cost int
}
type CacheLarge struct {
Capacity int
BaseLatency int
PenaltyPer10RPS float64
HitRates map[string]float64
Cost int
}
type DbReadReplica struct {
ReadCapacity int // RPS
BaseReadLatency int // ms
PenaltyPer10RPS float64
Cost int
}
type ComponentSpec struct {
LoadBalancer LoadBalancerSpec
WebServerSmall WebServerSmall
WebServerMedium WebServerMedium
CacheStandard CacheStandard
CacheLarge CacheLarge
DbReadReplica DbReadReplica
}
type FailureEvent struct {
Type string
Time int
}
type Level struct {
ID int
Description string
TargetRPS int
MaxP95Latency int
MaxMonthlyCost int
RequiredAvailability int
FailureEvents []FailureEvent
ComponentSpec ComponentSpec
SimulatedDurationSeconds int
}
type Metrics struct {
Cost int `json:"cost"`
P95 float64 `json:"p95"`
AchievedRPS int `json:"achievedRPS"`
Availability float64 `json:"availability"`
}
type EvaluationResult struct {
Pass bool `json:"pass"`
Metrics Metrics `json:"metrics"`
}
type Latencies struct {
L95WS float64
L95Cache float64
L95DBRead float64
L95TotalRead float64
}
type ValidationMetrics struct {
Cost int
P95 float64
AchievedRPS int
Availability float64
}
type ValidationResults struct {
Pass bool
Reason *string
Metrics *ValidationMetrics
}
type CacheType string
const (
CacheStandardType CacheType = "cacheStandard"
CacheLargeType CacheType = "cacheLarge"
)
type LevelSimulator struct {
Level Level
Design Design
Specs ComponentSpec
}
func (ls *LevelSimulator) ComputeCost() int {
s := ls.Specs
d := ls.Design
costLb := s.LoadBalancer.Cost
costWSSmall := d.NumWebServerSmall * s.WebServerSmall.Cost
costWSMedium := d.NumWebServerMedium * s.WebServerSmall.Cost
var costCache int
if d.CacheType == CacheStandardType {
costCache = s.CacheStandard.Cost
} else {
costCache = s.CacheLarge.Cost
}
costDB := s.DbReadReplica.Cost * (1 + d.NumDbReplicas)
return costLb + costWSSmall + costWSMedium + costCache + costDB
}
func (ls *LevelSimulator) ComputeRPS() (float64, float64) {
s := ls.Specs
d := ls.Design
l := ls.Level
totalRPS := l.TargetRPS
var hitRate float64
if d.CacheType == CacheStandardType {
hitRate = s.CacheStandard.HitRates[d.CacheTTL]
} else if d.CacheType == CacheLargeType {
hitRate = s.CacheLarge.HitRates[d.CacheTTL]
} else {
hitRate = 0.0
}
hitRPS := float64(totalRPS) * hitRate
missesRPS := float64(totalRPS) * (1 - hitRate)
return hitRPS, missesRPS
}
func (ls *LevelSimulator) ComputeLatencies() Latencies {
s := ls.Specs
d := ls.Design
_, missesRPS := ls.ComputeRPS()
capSmall := s.WebServerSmall.Capacity
capMedium := s.WebServerMedium.Capacity
weightedCount := d.NumWebServerSmall + (2 * d.NumWebServerSmall)
var L95WS float64
if weightedCount == 0 {
L95WS = math.Inf(1)
} else {
loadPerWeighted := missesRPS / float64(weightedCount)
L95WSSmall := 0.0
if d.NumWebServerSmall > 0 {
if loadPerWeighted <= float64(capSmall) {
L95WSSmall = float64(s.WebServerSmall.BaseLatency)
} else {
L95WSSmall = (float64(s.WebServerSmall.BaseLatency) + s.WebServerSmall.PenaltyPerRPS*(loadPerWeighted-float64(capSmall)))
}
}
L95WSMedium := 0.0
if d.NumWebServerMedium > 0 {
if loadPerWeighted <= float64(capMedium) {
L95WSMedium = float64(s.WebServerSmall.BaseLatency)
} else {
L95WSMedium = (float64(s.WebServerSmall.BaseLatency) + s.WebServerMedium.PenaltyPerRPS*(loadPerWeighted-float64(capMedium)))
}
}
L95WS = math.Max(L95WSSmall, L95WSMedium)
}
var L95Cache float64
if d.CacheType == CacheStandardType {
L95Cache = float64(s.CacheStandard.BaseLatency)
} else if d.CacheType == CacheLargeType {
L95Cache = float64(s.CacheLarge.BaseLatency)
} else {
L95Cache = 0.0
}
readCap := s.DbReadReplica.ReadCapacity
baseReadLat := s.DbReadReplica.BaseReadLatency
penPer10 := s.DbReadReplica.PenaltyPer10RPS
numReps := d.NumDbReplicas
var L95DbRead float64
if numReps == 0 {
if missesRPS <= float64(readCap) {
L95DbRead = float64(baseReadLat)
} else {
excess := missesRPS - float64(readCap)
L95DbRead = float64(baseReadLat) + penPer10*(excess/10.0)
}
} else {
loadPerRep := missesRPS / float64(numReps)
if loadPerRep <= float64(readCap) {
L95DbRead = float64(baseReadLat)
} else {
loadPerRep := missesRPS / float64(numReps)
if loadPerRep <= float64(readCap) {
L95DbRead = float64(baseReadLat)
} else {
excess := loadPerRep - loadPerRep - float64(readCap)
L95DbRead = float64(baseReadLat) + penPer10*(excess/10.0)
}
}
}
LLb := s.LoadBalancer.BaseLatency
missPath := LLb + int(L95WS) + int(L95DbRead)
L95TotalRead := missPath
return Latencies{
L95WS: L95WS,
L95Cache: L95Cache,
L95DBRead: L95DbRead,
L95TotalRead: float64(L95TotalRead),
}
}
func (ls *LevelSimulator) ComputeAvailability() float64 {
simDuration := ls.Level.SimulatedDurationSeconds
totalDownTime := 0
for _, event := range ls.Level.FailureEvents {
tCrash := event.Time
if event.Type == "DB_MASTER_CRASH" {
if ls.Design.NumDbReplicas == 0 {
totalDownTime += (simDuration - tCrash)
} else {
delay := ls.Design.PromotionDelaySeconds
totalDownTime += delay
}
}
}
return (float64(simDuration) - float64(totalDownTime)) / float64(simDuration) * 100
}
func (ls *LevelSimulator) Validate() ValidationResults {
totalCost := ls.ComputeCost()
if totalCost > ls.Level.MaxMonthlyCost {
return ValidationResults{
Pass: false,
Metrics: Metrics{
Cost: totalCost,
P95: la,
},
}
}
}
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