Module: Bitfab::Replay

Defined in:
lib/bitfab/replay.rb

Overview

Replay historical traces through a traced method and create a test run.

Class Method Summary collapse

Class Method Details

.execute_item(item, receiver, method_name, test_run_id, input_source_span_id = nil, metrics = {}) ⇒ Object

Execute a single replay item: deserialize inputs, call method with replay context.



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# File 'lib/bitfab/replay.rb', line 158

def execute_item(item, receiver, method_name, test_run_id, input_source_span_id = nil, metrics = {})
  args, kwargs = Serialize.deserialize_inputs(item)

  fn_result = nil
  fn_error = nil

  ReplayContext.with_context(test_run_id:, input_source_span_id:) do
    fn_result = if kwargs.empty?
      receiver.send(method_name, *args)
    else
      receiver.send(method_name, *args, **kwargs)
    end
  rescue => e
    fn_error = e.message
  end

  {
    input: args,
    result: fn_result,
    original_output: item["output"],
    error: fn_error,
    duration_ms: metrics[:duration_ms],
    tokens: metrics[:tokens],
    model: metrics[:model]
  }
end

.extract_server_item_metrics(server_item) ⇒ Object

Pull durationMs / tokens / model from the start-replay server item. Normalizes to symbol-keyed tokens hash and nil-safe defaults so older servers without these fields still produce a consistent shape.



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# File 'lib/bitfab/replay.rb', line 139

def extract_server_item_metrics(server_item)
  raw_tokens = server_item["tokens"]
  tokens = if raw_tokens.is_a?(Hash)
    {
      input: raw_tokens["input"],
      output: raw_tokens["output"],
      cached: raw_tokens["cached"],
      total: raw_tokens["total"]
    }
  end

  {
    duration_ms: server_item["durationMs"],
    tokens:,
    model: server_item["model"]
  }
end

.extract_span_data(span) ⇒ Object

Extract input/output data from an external span’s rawData.



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# File 'lib/bitfab/replay.rb', line 124

def extract_span_data(span)
  raw_data = span["rawData"] || {}
  span_data = raw_data["span_data"] || {}

  {
    "input" => span_data["input"],
    "output" => span_data["output"],
    "inputSerialized" => span_data["input_serialized"],
    "outputSerialized" => span_data["output_serialized"]
  }
end

.process_items(http_client, server_items, receiver, method_name, test_run_id, max_concurrency) ⇒ Object

Process all replay items, optionally in parallel using threads.



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# File 'lib/bitfab/replay.rb', line 87

def process_items(http_client, server_items, receiver, method_name, test_run_id, max_concurrency)
  concurrency = max_concurrency || server_items.length

  if concurrency <= 1
    server_items.map { |item| process_single_item(http_client, item, receiver, method_name, test_run_id) }
  else
    results_mutex = Mutex.new
    results = []
    work_queue = server_items.each_with_index.to_a
    work_mutex = Mutex.new

    workers = [concurrency, server_items.length].min.times.map do
      Thread.new do
        loop do
          item, idx = work_mutex.synchronize { work_queue.shift }
          break unless item

          result = process_single_item(http_client, item, receiver, method_name, test_run_id)
          results_mutex.synchronize { results[idx] = result }
        end
      end
    end

    workers.each(&:join)
    results.compact
  end
end

.process_single_item(http_client, server_item, receiver, method_name, test_run_id) ⇒ Object

Fetch span data and execute a single replay item.



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# File 'lib/bitfab/replay.rb', line 116

def process_single_item(http_client, server_item, receiver, method_name, test_run_id)
  span = http_client.get_external_span(server_item["externalSpanId"])
  item_data = extract_span_data(span)
  metrics = extract_server_item_metrics(server_item)
  execute_item(item_data, receiver, method_name, test_run_id, span["id"], metrics)
end

.run(client, receiver, method_name, trace_function_key:, limit: 5, trace_ids: nil, max_concurrency: 10, code_change_description: nil, code_change_files: nil) ⇒ Hash

Replay historical traces through a method and create a test run.

Fetches the last N traces for the given trace function key, re-runs each through the provided receiver and method, and returns comparison data.

Parameters:

  • client (Bitfab::Client) —

    the Bitfab client instance

  • receiver (Object, Class) —

    an instance for instance methods, or a Class for class methods

  • method_name (Symbol) —

    the method to replay

  • trace_function_key (String) —

    the trace function key for this method

  • limit (Integer) (defaults to: 5) —

    maximum number of traces to replay (default: 5)

  • trace_ids (Array<String>, nil) (defaults to: nil) —

    optional list of trace IDs to filter

  • max_concurrency (Integer, nil) (defaults to: 10) —

    max threads for parallel replay (default: 10)

  • code_change_description (String, nil) (defaults to: nil) —

    optional rationale for the code change being tested in this replay (stored on the experiment)

  • code_change_files (Array<Hash>, nil) (defaults to: nil) —

    optional list of edited files, each as { path:, before:, after: } (empty string for new/deleted files)

Returns:

  • (Hash) —

    with :items, :test_run_id, :test_run_url



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# File 'lib/bitfab/replay.rb', line 50

def run(client, receiver, method_name, trace_function_key:, limit: 5, trace_ids: nil, max_concurrency: 10,
  code_change_description: nil, code_change_files: nil)
  http_client = client.instance_variable_get(:@http_client)

  replay_data = http_client.start_replay(
    trace_function_key,
    limit,
    trace_ids:,
    code_change_description:,
    code_change_files:
  )
  test_run_id = replay_data["testRunId"]
  test_run_url = replay_data["testRunUrl"]
  server_items = replay_data["items"] || []

  result_items = if server_items.any?
    process_items(http_client, server_items, receiver, method_name, test_run_id, max_concurrency)
  else
    []
  end

  Bitfab.flush_traces

  begin
    http_client.complete_replay(test_run_id)
  rescue => e
    warn "Bitfab: Failed to complete replay: #{e.message}"
  end

  {
    items: result_items,
    test_run_id:,
    test_run_url: "#{client.service_url}#{test_run_url}"
  }
end