sampler

package
v0.6.20 Latest Latest
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 Go to latest Published: Sep 12, 2026 License: Apache-2.0 Imports: 6 Imported by: 0

Documentation

Overview

Package sampler implements per-kind sampling and post-bus filtering for the agent.

The bus's own Filter narrows by EventKind and NodeID — coarse-grained, fast. The Sampler refines this with two further dimensions the bus deliberately does not know about:

  • Per-kind sampling rate (0.0–1.0). The admin server may say "ship 10 % of SQL events but 100 % of HTTP" because SQL volume can overwhelm the channel during normal load.
  • HTTP-specific filters (path glob, method, status class) and SQL- specific filters (model name) that the bus is intentionally agnostic about. Forwarding these to the bus would couple it to wire concepts it does not own.

Sampler is goroutine-safe; the rate map and the filter are read on every event. Rates and filters can be updated atomically via Update.

Index

Constants

This section is empty.

Variables

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Functions

This section is empty.

Types

type Decision 

type Decision uint8

Decision is the outcome of running the sampler over one event. 

const (
	// Accept means the event passes; the agent should forward it.
	Accept Decision = iota
	// DropSampled means the per-kind rate randomly excluded this event.
	DropSampled
	// DropFiltered means a wire-level filter rejected it.
	DropFiltered
)

type Sampler 

type Sampler struct {
	// contains filtered or unexported fields
}

Sampler groups one filter and its sampling rates, behind an RWMutex so the server-driven Subscribe can update it without tearing.

func New 

func New(filter *adminv1.Filter, rates map[string]float32) *Sampler

New constructs a Sampler with the given starting filter and rate map. Pass nil filter for "no constraint" and nil rates for "100 % all kinds".

func (*Sampler) Decide 

func (s *Sampler) Decide(e observability.Event) Decision

Decide runs the rate roll first (cheap), then the filter (more work). Returns one of Accept / DropSampled / DropFiltered. The caller is responsible for incrementing the right counter.

func (*Sampler) Update 

func (s *Sampler) Update(filter *adminv1.Filter, rates map[string]float32)

Update replaces the filter and rates atomically.

Source Files

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