134 lines
3.1 KiB
Go
134 lines
3.1 KiB
Go
package zerolog
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import (
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"math/rand"
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"sync/atomic"
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"time"
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)
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var (
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// Often samples log every ~ 10 events.
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Often = RandomSampler(10)
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// Sometimes samples log every ~ 100 events.
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Sometimes = RandomSampler(100)
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// Rarely samples log every ~ 1000 events.
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Rarely = RandomSampler(1000)
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)
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// Sampler defines an interface to a log sampler.
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type Sampler interface {
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// Sample returns true if the event should be part of the sample, false if
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// the event should be dropped.
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Sample(lvl Level) bool
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}
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// RandomSampler use a PRNG to randomly sample an event out of N events,
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// regardless of their level.
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type RandomSampler uint32
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// Sample implements the Sampler interface.
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func (s RandomSampler) Sample(lvl Level) bool {
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if s <= 0 {
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return false
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}
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if rand.Intn(int(s)) != 0 {
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return false
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}
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return true
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}
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// BasicSampler is a sampler that will send every Nth events, regardless of
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// their level.
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type BasicSampler struct {
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N uint32
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counter uint32
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}
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// Sample implements the Sampler interface.
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func (s *BasicSampler) Sample(lvl Level) bool {
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n := s.N
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if n == 1 {
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return true
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}
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c := atomic.AddUint32(&s.counter, 1)
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return c%n == 1
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}
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// BurstSampler lets Burst events pass per Period then pass the decision to
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// NextSampler. If Sampler is not set, all subsequent events are rejected.
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type BurstSampler struct {
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// Burst is the maximum number of event per period allowed before calling
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// NextSampler.
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Burst uint32
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// Period defines the burst period. If 0, NextSampler is always called.
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Period time.Duration
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// NextSampler is the sampler used after the burst is reached. If nil,
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// events are always rejected after the burst.
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NextSampler Sampler
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counter uint32
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resetAt int64
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}
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// Sample implements the Sampler interface.
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func (s *BurstSampler) Sample(lvl Level) bool {
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if s.Burst > 0 && s.Period > 0 {
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if s.inc() <= s.Burst {
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return true
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}
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}
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if s.NextSampler == nil {
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return false
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}
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return s.NextSampler.Sample(lvl)
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}
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func (s *BurstSampler) inc() uint32 {
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now := time.Now().UnixNano()
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resetAt := atomic.LoadInt64(&s.resetAt)
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var c uint32
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if now > resetAt {
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c = 1
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atomic.StoreUint32(&s.counter, c)
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newResetAt := now + s.Period.Nanoseconds()
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reset := atomic.CompareAndSwapInt64(&s.resetAt, resetAt, newResetAt)
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if !reset {
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// Lost the race with another goroutine trying to reset.
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c = atomic.AddUint32(&s.counter, 1)
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}
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} else {
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c = atomic.AddUint32(&s.counter, 1)
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}
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return c
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}
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// LevelSampler applies a different sampler for each level.
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type LevelSampler struct {
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TraceSampler, DebugSampler, InfoSampler, WarnSampler, ErrorSampler Sampler
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}
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func (s LevelSampler) Sample(lvl Level) bool {
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switch lvl {
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case TraceLevel:
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if s.TraceSampler != nil {
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return s.TraceSampler.Sample(lvl)
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}
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case DebugLevel:
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if s.DebugSampler != nil {
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return s.DebugSampler.Sample(lvl)
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}
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case InfoLevel:
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if s.InfoSampler != nil {
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return s.InfoSampler.Sample(lvl)
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}
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case WarnLevel:
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if s.WarnSampler != nil {
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return s.WarnSampler.Sample(lvl)
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}
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case ErrorLevel:
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if s.ErrorSampler != nil {
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return s.ErrorSampler.Sample(lvl)
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}
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}
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return true
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}
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