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sampler_scheduler.go
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sampler_scheduler.go
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package internal
import (
"math/rand"
"os"
"strconv"
"sync"
"time"
"github.com/instana/go-sensor/autoprofile/internal/logger"
)
var (
GetPID = GetLocalPID
samplerActive Flag
)
func GetLocalPID() string {
logger.Warn("using the local process pid as a default")
return strconv.Itoa(os.Getpid())
}
type SamplerConfig struct {
LogPrefix string
ReportOnly bool
MaxProfileDuration int64
MaxSpanDuration int64
MaxSpanCount int32
SamplingInterval int64
ReportInterval int64
}
type Sampler interface {
Profile(duration int64, timespan int64) (*Profile, error)
Start() error
Stop() error
Reset()
}
type SamplerScheduler struct {
profileRecorder *Recorder
sampler Sampler
config SamplerConfig
started Flag
samplerTimer *Timer
reportTimer *Timer
profileLock *sync.Mutex
profileStart int64
samplingDuration int64
samplerStart int64
samplerTimeout *Timer
}
func NewSamplerScheduler(profileRecorder *Recorder, samp Sampler, config SamplerConfig) *SamplerScheduler {
pr := &SamplerScheduler{
profileRecorder: profileRecorder,
sampler: samp,
config: config,
profileLock: &sync.Mutex{},
}
return pr
}
func (ss *SamplerScheduler) Start() {
if !ss.started.SetIfUnset() {
return
}
ss.profileLock.Lock()
defer ss.profileLock.Unlock()
ss.Reset()
if !ss.config.ReportOnly {
ss.samplerTimer = NewTimer(0, time.Duration(ss.config.SamplingInterval)*time.Second, func() {
time.Sleep(time.Duration(rand.Int63n(ss.config.SamplingInterval-ss.config.MaxSpanDuration)) * time.Second)
ss.startProfiling()
})
}
ss.reportTimer = NewTimer(0, time.Duration(ss.config.ReportInterval)*time.Second, func() {
ss.Report()
})
}
func (ss *SamplerScheduler) Stop() {
if !ss.started.UnsetIfSet() {
return
}
if ss.samplerTimer != nil {
ss.samplerTimer.Stop()
}
if ss.reportTimer != nil {
ss.reportTimer.Stop()
}
}
func (ss *SamplerScheduler) Reset() {
ss.sampler.Reset()
ss.profileStart = time.Now().Unix()
ss.samplingDuration = 0
}
func (ss *SamplerScheduler) Report() {
if !ss.started.IsSet() {
return
}
profileTimespan := time.Now().Unix() - ss.profileStart
ss.profileLock.Lock()
defer ss.profileLock.Unlock()
if !ss.config.ReportOnly && ss.samplingDuration == 0 {
return
}
logger.Debug(ss.config.LogPrefix, "recording profile")
profile, err := ss.sampler.Profile(ss.samplingDuration, profileTimespan)
if err != nil {
logger.Error(err)
return
} else {
if len(profile.Roots) == 0 {
logger.Debug(ss.config.LogPrefix, "not recording empty profile")
ss.Reset()
return
}
externalPID := GetPID()
if externalPID != "" {
profile.ProcessID = externalPID
logger.Debug("using external PID", externalPID)
} else {
logger.Info("external PID from agent is not available, using own PID")
}
ss.profileRecorder.Record(profile.ToMap())
logger.Debug(ss.config.LogPrefix, "recorded profile")
}
ss.Reset()
}
func (ss *SamplerScheduler) startProfiling() bool {
if !ss.started.IsSet() {
return false
}
ss.profileLock.Lock()
defer ss.profileLock.Unlock()
if ss.samplingDuration > ss.config.MaxProfileDuration*1e9 {
logger.Debug(ss.config.LogPrefix, "max sampling duration reached")
return false
}
if !samplerActive.SetIfUnset() {
return false
}
logger.Debug(ss.config.LogPrefix, "starting")
err := ss.sampler.Start()
if err != nil {
samplerActive.Unset()
logger.Error(err)
return false
}
ss.samplerStart = time.Now().UnixNano()
ss.samplerTimeout = NewTimer(time.Duration(ss.config.MaxSpanDuration)*time.Second, 0, func() {
ss.stopSampler()
samplerActive.Unset()
})
return true
}
func (ss *SamplerScheduler) stopSampler() {
ss.profileLock.Lock()
defer ss.profileLock.Unlock()
if ss.samplerTimeout != nil {
ss.samplerTimeout.Stop()
}
err := ss.sampler.Stop()
if err != nil {
logger.Error(err)
return
}
logger.Debug(ss.config.LogPrefix, "stopped")
ss.samplingDuration += time.Now().UnixNano() - ss.samplerStart
}