github.com/facebookincubator/go-belt@v0.0.0-20230703220935-39cd348f1a38/pkg/sampler/sampler.go (about)

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    12  
    13  package sampler
    14  
    15  import (
    16  	"math/rand"
    17  	"sync/atomic"
    18  
    19  	"github.com/facebookincubator/go-belt"
    20  )
    21  
    22  // Sampler defines if a specific entry should stay (be kept) or it should be
    23  // sampled out / optimized out.
    24  type Sampler interface {
    25  	ShouldStay(belt.TraceIDs) bool
    26  }
    27  
    28  // RandomSampler is an implementation of Sampler, which just decides randomly.
    29  type RandomSampler float64
    30  
    31  // NewRandomSampler returns a new instance of RandomSampler
    32  func NewRandomSampler(fraction float64) Sampler {
    33  	return RandomSampler(fraction)
    34  }
    35  
    36  // ShouldStay implements Sampler
    37  func (s RandomSampler) ShouldStay(_ belt.TraceIDs) bool {
    38  	return rand.Float64() < float64(s)
    39  }
    40  
    41  // CountSampler is an implementation of Sampler, which evenly allows to stay
    42  // each N-th entry.
    43  type CountSampler struct {
    44  	// Count is the amount of entries were met already.
    45  	Count uint32
    46  
    47  	// Each is the N of ("each N-th entry").
    48  	Each uint32
    49  }
    50  
    51  // NewCountSampler returns a new instance of CountSampler
    52  func NewCountSampler(each uint32) Sampler {
    53  	return &CountSampler{
    54  		Each: each,
    55  	}
    56  }
    57  
    58  // ShouldStay implements Sampler.
    59  func (s *CountSampler) ShouldStay(_ belt.TraceIDs) bool {
    60  	return atomic.AddUint32(&s.Count, 1)%s.Each == 0
    61  }