Package brave.sampler

Class BoundarySampler

java.lang.Object
brave.sampler.Sampler
brave.sampler.BoundarySampler
public final class BoundarySampler
extends Sampler
This sampler is appropriate for high-traffic instrumentation (ex edge web servers that each receive >100K requests) who provision random trace ids, and make the sampling decision only once. It defends against nodes in the cluster selecting exactly the same ids.

Implementation

This uses modulo 10000 arithmetic, which allows a minimum probability of 0.01%. Trace id collision was noticed in practice in the Twitter front-end cluster. A random salt is here to defend against nodes in the same cluster sampling exactly the same subset of trace ids. The goal was full 64-bit coverage of trace IDs on multi-host deployments.

Based on https://github.com/twitter/finagle/blob/b6b1d0414fa24ed0c8bb5112985a4e9c9bcd3c9e/finagle-zipkin-core/src/main/scala/com/twitter/finagle/zipkin/core/Sampler.scala#L68

  • Method Details

    • create

      public static Sampler create​(float probability)
      Parameters:
      probability - 0 means never sample, 1 means always sample. Otherwise minimum probability is 0.0001, or 0.01% of traces

    • isSampled

      public boolean isSampled​(long traceId)
      Returns true when abs(traceId) <= boundary
      Specified by:
      isSampled in class Sampler
      Parameters:
      traceId - The trace ID to be decided on, can be ignored

    • toString

      public String toString()
      Overrides:
      toString in class Object