Module: Braintrust::Contrib::RubyLLM::Instrumentation::Common

Defined in:
lib/braintrust/contrib/ruby_llm/instrumentation/common.rb

Overview

Common utilities for RubyLLM instrumentation.

Class Method Summary collapse

Class Method Details

.parse_usage_tokens(usage) ⇒ Hash<String, Integer>

Parse RubyLLM usage tokens into normalized Braintrust metrics. RubyLLM normalizes token fields from all providers (OpenAI, Anthropic, etc.) into a consistent format:

- input_tokens: prompt tokens sent
- output_tokens: completion tokens received
- cached_tokens: tokens read from cache
- cache_creation_tokens: tokens written to cache

Parameters:

  • usage (Hash, Object) —

    usage object from RubyLLM response

Returns:

  • (Hash<String, Integer>) —

    normalized metrics for Braintrust



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# File 'lib/braintrust/contrib/ruby_llm/instrumentation/common.rb', line 19

def self.parse_usage_tokens(usage)
  metrics = {}
  return metrics unless usage

  usage_hash = usage.respond_to?(:to_h) ? usage.to_h : usage
  return metrics unless usage_hash.is_a?(Hash)

  # RubyLLM normalized field mappings → Braintrust metrics
  field_map = {
    "input_tokens" => "prompt_tokens",
    "output_tokens" => "completion_tokens",
    "cached_tokens" => "prompt_cached_tokens",
    "cache_creation_tokens" => "prompt_cache_creation_tokens"
  }

  usage_hash.each do |key, value|
    next unless value.is_a?(Numeric)
    key_str = key.to_s
    target = field_map[key_str]
    metrics[target] = value.to_i if target
  end

  # Accumulate cache tokens into prompt_tokens (matching TS/Python SDKs)
  prompt_tokens = (metrics["prompt_tokens"] || 0) +
    (metrics["prompt_cached_tokens"] || 0) +
    (metrics["prompt_cache_creation_tokens"] || 0)
  metrics["prompt_tokens"] = prompt_tokens if prompt_tokens > 0

  # Calculate total
  if metrics.key?("prompt_tokens") && metrics.key?("completion_tokens")
    metrics["tokens"] = metrics["prompt_tokens"] + metrics["completion_tokens"]
  end

  metrics
end