Class: PumaMetricsEngine::QueueTimeTracker

Inherits:
Object
  • Object
show all
Defined in:
lib/puma_metrics_engine/queue_time_tracker.rb

Constant Summary collapse

TTL_SECONDS =

5 minutes

300
REQUESTS_KEY = 
"puma:request_timestamps"
QUEUE_TIMES_KEY = 
"puma:queue_times"

Instance Method Summary collapse

Constructor Details

#initialize(app) ⇒ QueueTimeTracker

Returns a new instance of QueueTimeTracker.



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# File 'lib/puma_metrics_engine/queue_time_tracker.rb', line 9

def initialize(app)
  @app = app
end

Instance Method Details

#call(env) ⇒ Object 



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# File 'lib/puma_metrics_engine/queue_time_tracker.rb', line 13

def call(env)
  request_start_time = extract_request_start_time(env)
  process_start_time = Time.now.to_f

  # Log header presence for debugging
  if defined?(Rails)
    header_value = env["HTTP_X_REQUEST_START"] || env["X-Request-Start"]
    Rails.logger.debug("[QueueTimeTracker] X-Request-Start header: #{header_value.inspect}") if header_value
    Rails.logger.debug("[QueueTimeTracker] No X-Request-Start header found") unless header_value
  end

  status, headers, response = @app.call(env)

  # Calculate queue time if we have request start time
  begin
    if request_start_time
      queue_time_ms = ((process_start_time - request_start_time) * 1000).round(2)
      
      # Only store if queue time is reasonable (positive and less than 1 hour)
      # Negative values indicate clock skew, very large values are likely errors
      if queue_time_ms >= 0 && queue_time_ms < 3_600_000
        timestamp = process_start_time
        # Store in Redis asynchronously to avoid blocking the request
        store_metrics_async(timestamp, queue_time_ms)
        Rails.logger.debug("[QueueTimeTracker] Stored queue time: #{queue_time_ms}ms") if defined?(Rails)
      else
        # Still track request timestamp even if queue time is invalid
        Rails.logger.warn("[QueueTimeTracker] Invalid queue time: #{queue_time_ms}ms (rejected)") if defined?(Rails)
        store_request_timestamp_async(process_start_time)
      end
    else
      # Still track request timestamp even without queue time
      store_request_timestamp_async(process_start_time)
    end
  rescue StandardError => e
    # Don't let tracking errors break the request
    Rails.logger.error("[QueueTimeTracker] Error: #{e.message}") if defined?(Rails)
    Rails.logger.error("[QueueTimeTracker] Backtrace: #{e.backtrace.first(5).join("\n")}") if defined?(Rails)
  end

  [status, headers, response]
end