Module brave
Package brave.sampler

Class Sampler

  • Direct Known Subclasses:
    BoundarySampler, CountingSampler, RateLimitingSampler
    public abstract class Sampler
extends java.lang.Object
    Sampler is responsible for deciding if a particular trace should be "sampled", i.e. whether the overhead of tracing will occur and/or if a trace will be reported to the collection tier.

    Zipkin v1 uses before-the-fact sampling. This means that the decision to keep or drop the trace is made before any work is measured, or annotations are added. As such, the input parameter to zipkin v1 samplers is the trace ID (lower 64-bits under the assumption all bits are random).

    The instrumentation sampling decision happens once, at the root of the trace, and is propagated downstream. For this reason, the algorithm needn't be consistent based on trace ID.

    • Constructor Summary

      Constructors 
      Constructor Description
      Sampler()  

    • Method Summary

      All Methods Static Methods Instance Methods Abstract Methods Concrete Methods 
      Modifier and Type Method Description
      static Sampler create​(float probability)
      Returns a sampler, given a probability expressed as a percentage.
      abstract boolean isSampled​(long traceId)
      Returns true if the trace ID should be measured.

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    • Field Detail

      • ALWAYS_SAMPLE

        public static final Sampler ALWAYS_SAMPLE

      • NEVER_SAMPLE

        public static final Sampler NEVER_SAMPLE

    • Constructor Detail

      • Sampler

        public Sampler()

    • Method Detail

      • isSampled

        public abstract boolean isSampled​(long traceId)
        Returns true if the trace ID should be measured.
        Parameters:
        traceId - The trace ID to be decided on, can be ignored

      • create

        public static Sampler create​(float probability)
        Returns a sampler, given a probability expressed as a percentage.

        The sampler returned is good for low volumes of traffic (<100K requests), as it is precise. If you have high volumes of traffic, consider BoundarySampler.

        Parameters:
        probability - probability a trace will be sampled. minimum is 0.01, or 1% of traces