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|
package statsengine
import (
"math"
"math/rand"
"sort"
"time"
"ior/internal/event"
"ior/internal/types"
)
const syscallReservoirSampleCapDefault = 10_000
const syscallPercentileRecomputeStepDefault = 256
type syscallAccumulator struct {
byID map[types.TraceId]*syscallStats
sampleCap int
rng *rand.Rand
}
type syscallStats struct {
traceID types.TraceId
name string
count uint64
errorCount uint64
totalBytes uint64
totalLatency uint64
minLatency uint64
maxLatency uint64
seenLatencies uint64
samples []uint64
sampleVersion uint64
lastPercentileVersion uint64
cachedP50 uint64
cachedP95 uint64
cachedP99 uint64
}
type syscallSnapshotInput struct {
traceID types.TraceId
name string
count uint64
errorCount uint64
totalBytes uint64
totalLatency uint64
minLatency uint64
maxLatency uint64
p50Latency uint64
p95Latency uint64
p99Latency uint64
}
func newSyscallAccumulator() *syscallAccumulator {
return newSyscallAccumulatorWithConfig(syscallReservoirSampleCapDefault, rand.New(rand.NewSource(time.Now().UnixNano())))
}
func newSyscallAccumulatorWithConfig(sampleCap int, rng *rand.Rand) *syscallAccumulator {
if sampleCap <= 0 {
sampleCap = syscallReservoirSampleCapDefault
}
if rng == nil {
rng = rand.New(rand.NewSource(time.Now().UnixNano()))
}
return &syscallAccumulator{
byID: make(map[types.TraceId]*syscallStats),
sampleCap: sampleCap,
rng: rng,
}
}
func (a *syscallAccumulator) Add(pair *event.Pair) {
if a == nil || pair == nil || pair.EnterEv == nil {
return
}
traceID := pair.EnterEv.GetTraceId()
stats := a.byID[traceID]
if stats == nil {
stats = &syscallStats{traceID: traceID, name: traceID.Name()}
a.byID[traceID] = stats
}
stats.count++
stats.totalBytes += pair.Bytes
stats.totalLatency += pair.Duration
stats.updateMinMax(pair.Duration)
stats.addSample(pair.Duration, a.sampleCap, a.rng)
if retEv, ok := pair.ExitEv.(*types.RetEvent); ok && retEv.Ret < 0 {
stats.errorCount++
}
}
func (a *syscallAccumulator) Snapshot(elapsed time.Duration) []SyscallSnapshot {
if a == nil {
return nil
}
return buildSyscallSnapshots(a.snapshotInputs(), elapsed)
}
func (a *syscallAccumulator) snapshotInputs() []syscallSnapshotInput {
if a == nil {
return nil
}
inputs := make([]syscallSnapshotInput, 0, len(a.byID))
for _, stats := range a.byID {
stats.ensurePercentiles()
inputs = append(inputs, syscallSnapshotInput{
traceID: stats.traceID,
name: stats.name,
count: stats.count,
errorCount: stats.errorCount,
totalBytes: stats.totalBytes,
totalLatency: stats.totalLatency,
minLatency: stats.minLatency,
maxLatency: stats.maxLatency,
p50Latency: stats.cachedP50,
p95Latency: stats.cachedP95,
p99Latency: stats.cachedP99,
})
}
return inputs
}
func buildSyscallSnapshots(inputs []syscallSnapshotInput, elapsed time.Duration) []SyscallSnapshot {
rateDiv := elapsed.Seconds()
result := make([]SyscallSnapshot, 0, len(inputs))
for _, in := range inputs {
result = append(result, in.toSnapshot(rateDiv))
}
sort.Slice(result, func(i, j int) bool {
if result[i].Count != result[j].Count {
return result[i].Count > result[j].Count
}
return result[i].Name < result[j].Name
})
return result
}
func (s *syscallStats) updateMinMax(duration uint64) {
if s.count == 1 || duration < s.minLatency {
s.minLatency = duration
}
if duration > s.maxLatency {
s.maxLatency = duration
}
}
func (s *syscallStats) addSample(duration uint64, cap int, rng *rand.Rand) {
s.seenLatencies++
if len(s.samples) < cap {
s.samples = append(s.samples, duration)
s.sampleVersion++
return
}
idx := rng.Int63n(int64(s.seenLatencies))
if idx >= int64(cap) {
return
}
s.samples[idx] = duration
s.sampleVersion++
}
func (s *syscallStats) ensurePercentiles() {
if s.lastPercentileVersion == s.sampleVersion {
return
}
if s.lastPercentileVersion != 0 && s.sampleVersion-s.lastPercentileVersion < syscallPercentileRecomputeStepDefault {
return
}
if len(s.samples) == 0 {
s.cachedP50, s.cachedP95, s.cachedP99 = 0, 0, 0
s.lastPercentileVersion = s.sampleVersion
return
}
sorted := append([]uint64(nil), s.samples...)
sort.Slice(sorted, func(i, j int) bool { return sorted[i] < sorted[j] })
s.cachedP50 = samplePercentile(sorted, 0.50)
s.cachedP95 = samplePercentile(sorted, 0.95)
s.cachedP99 = samplePercentile(sorted, 0.99)
s.lastPercentileVersion = s.sampleVersion
}
func (s syscallSnapshotInput) toSnapshot(rateDiv float64) SyscallSnapshot {
return SyscallSnapshot{
TraceID: s.traceID,
Name: s.name,
Count: s.count,
RatePerSec: safeRate(s.count, rateDiv),
Errors: s.errorCount,
Bytes: s.totalBytes,
LatencyMinNs: s.minLatency,
LatencyMaxNs: s.maxLatency,
LatencyMeanNs: float64(s.totalLatency) / float64(maxU64(s.count, 1)),
LatencyP50Ns: s.p50Latency,
LatencyP95Ns: s.p95Latency,
LatencyP99Ns: s.p99Latency,
}
}
func samplePercentile(sorted []uint64, p float64) uint64 {
if len(sorted) == 0 {
return 0
}
if p <= 0 {
return sorted[0]
}
if p >= 1 {
return sorted[len(sorted)-1]
}
rank := int(math.Ceil(p*float64(len(sorted)))) - 1
if rank < 0 {
rank = 0
}
if rank >= len(sorted) {
rank = len(sorted) - 1
}
return sorted[rank]
}
func safeRate(count uint64, elapsedSeconds float64) float64 {
if elapsedSeconds <= 0 {
return 0
}
return float64(count) / elapsedSeconds
}
func maxU64(a, b uint64) uint64 {
if a > b {
return a
}
return b
}
|
