Class: DeadBro::Subscriber

Inherits:
Object
  • Object
show all
Defined in:
lib/dead_bro/subscriber.rb

Constant Summary collapse

EVENT_NAME = 
"process_action.action_controller"
SENSITIVE_SEGMENT_RE =

Matched against a key segment (delimited by start/end, underscore, dash, or bracket) so nested and prefixed/suffixed keys are caught — e.g. user, access_token, client_secret — without redacting innocent keys like passenger_count or cardinality.

/(?:\A|[_\-\[])(password|passwd|secret|token|api_?key|access_?key|auth|authorization|credential|ssn|credit_?card|card_?number|cvv|cvc)(?:\z|[_\-\]])/i

Class Method Summary collapse

Class Method Details

.build_cause_chain(exception) ⇒ Object 



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# File 'lib/dead_bro/subscriber.rb', line 469

def self.build_cause_chain(exception)
  return [] unless exception
  chain = []
  cause = exception.cause
  depth = 0
  while cause && depth < 5
    chain << {
      exception_class: cause.class.name,
      message: cause.message.to_s[0, 500],
      backtrace_top: Array(cause.backtrace).first(3)
    }
    cause = cause.cause
    depth += 1
  end
  chain
rescue
  []
end

.cache_hits(data) ⇒ Object 



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# File 'lib/dead_bro/subscriber.rb', line 413

def self.cache_hits(data)
  if data[:cache_hits]
    data[:cache_hits]
  elsif defined?(Rails) && Rails.cache.respond_to?(:stats)
    begin
      Rails.cache.stats[:hits]
    rescue
      0
    end
  else
    0
  end
rescue
  0
end

.cache_misses(data) ⇒ Object 



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# File 'lib/dead_bro/subscriber.rb', line 429

def self.cache_misses(data)
  if data[:cache_misses]
    data[:cache_misses]
  elsif defined?(Rails) && Rails.cache.respond_to?(:stats)
    begin
      Rails.cache.stats[:misses]
    rescue
      0
    end
  else
    0
  end
rescue
  0
end

.compute_error_fingerprint(exception) ⇒ Object 



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# File 'lib/dead_bro/subscriber.rb', line 460

def self.compute_error_fingerprint(exception)
  return nil unless exception
  top_frame = Array(exception.backtrace).first.to_s.gsub(/:\d+:in /, ":N:in ")
  input = "#{exception.class.name}|#{normalize_error_message(exception.message)}|#{top_frame}"
  Digest::SHA256.hexdigest(input)[0, 16]
rescue
  nil
end

.drain_request_tracking ⇒ Object

Release per-subscriber thread-local state when we've decided not to build a payload (disabled / excluded / sampled out). Without this, a subsequent request reusing the same Puma thread would see stale queries/events.



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# File 'lib/dead_bro/subscriber.rb', line 237

def self.drain_request_tracking
  # wait_for_explains: false — the result is discarded, so don't block this
  # thread waiting on pending EXPLAIN plans.
  DeadBro::SqlSubscriber.stop_request_tracking(wait_for_explains: false) if defined?(DeadBro::SqlSubscriber)
  DeadBro::CacheSubscriber.stop_request_tracking if defined?(DeadBro::CacheSubscriber)
  DeadBro::RedisSubscriber.stop_request_tracking if defined?(DeadBro::RedisSubscriber)
  DeadBro::ElasticsearchSubscriber.stop_request_tracking if defined?(DeadBro::ElasticsearchSubscriber)
  DeadBro::ViewRenderingSubscriber.stop_request_tracking if defined?(DeadBro::ViewRenderingSubscriber)
  DeadBro::LightweightMemoryTracker.stop_request_tracking if defined?(DeadBro::LightweightMemoryTracker)
  DeadBro::MemoryPhaseTracker.stop_request_tracking if defined?(DeadBro::MemoryPhaseTracker)
  if Thread.current[:dead_bro_alloc_active]
    DeadBro::MemoryTrackingSubscriber.stop_request_tracking if defined?(DeadBro::MemoryTrackingSubscriber)
    DeadBro::AllocationSourceSampler.stop if defined?(DeadBro::AllocationSourceSampler)
  end
  Thread.current[:dead_bro_alloc_active] = nil
  Thread.current[:dead_bro_http_events] = nil
  DeadBro::DbConnectionSubscriber.stop_request_tracking if defined?(DeadBro::DbConnectionSubscriber)
  DeadBro::GcTracker.stop_request_tracking if defined?(DeadBro::GcTracker)
  DeadBro::ArObjectTracker.stop_request_tracking if defined?(DeadBro::ArObjectTracker)
  DeadBro::CpuTracker.stop_request_tracking if defined?(DeadBro::CpuTracker)
rescue
  # Best effort — draining must never raise from the notifications callback.
end

.extract_user_id(data) ⇒ Object 



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# File 'lib/dead_bro/subscriber.rb', line 445

def self.extract_user_id(data)
  data[:headers].env["warden"].user.id
rescue
  nil
end

.gc_stats ⇒ Object 



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# File 'lib/dead_bro/subscriber.rb', line 379

def self.gc_stats
  if defined?(GC) && GC.respond_to?(:stat)
    stats = GC.stat
    {
      count: stats[:count] || 0,
      heap_allocated_pages: stats[:heap_allocated_pages] || 0,
      heap_sorted_pages: stats[:heap_sorted_pages] || 0,
      total_allocated_objects: stats[:total_allocated_objects] || 0
    }
  else
    {}
  end
rescue
  {}
end

.memory_usage_mb ⇒ Object 



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# File 'lib/dead_bro/subscriber.rb', line 373

def self.memory_usage_mb
  DeadBro::MemoryHelpers.rss_mb
rescue
  0
end

.normalize_error_message(msg) ⇒ Object 



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# File 'lib/dead_bro/subscriber.rb', line 451

def self.normalize_error_message(msg)
  msg.to_s
    .gsub(/\b[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}\b/i, "UUID")
    .gsub(/\b\d+\b/, "N")
    .gsub(/"[^"]*"/, '"?"')
    .gsub(/'[^']*'/, "'?'")
    .strip
end

.safe_params(data) ⇒ Object 



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# File 'lib/dead_bro/subscriber.rb', line 268

def self.safe_params(data)
  return {} unless data[:params]

  params = data[:params]
  begin
    params = params.to_unsafe_h if params.respond_to?(:to_unsafe_h)
  rescue
  end

  unless params.is_a?(Hash)
    return {}
  end

  # Remove router-provided keys that we already send at top-level
  router_keys = %w[controller action format]

  filtered = params.dup
  router_keys.each { |k| filtered.delete(k) || filtered.delete(k.to_sym) }

  # Truncate deeply to keep payload small and safe. truncate_value also redacts
  # sensitive keys at every nesting level (e.g. user[password]).
  truncate_value(filtered)
rescue
  {}
end

.safe_path(data) ⇒ Object 



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# File 'lib/dead_bro/subscriber.rb', line 261

def self.safe_path(data)
  path = data[:path] || (data[:request] && data[:request].path)
  sanitize_string(path)
rescue
  ""
end

.safe_user_agent(data) ⇒ Object 



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# File 'lib/dead_bro/subscriber.rb', line 329

def self.safe_user_agent(data)
  begin
    # Prefer request object if available
    if data[:request]
      ua = nil
      if data[:request].respond_to?(:user_agent)
        ua = data[:request].user_agent
      elsif data[:request].respond_to?(:env)
        ua = data[:request].env && data[:request].env["HTTP_USER_AGENT"]
      end
      return sanitize_string(ua)[0..200]
    end

    # Fallback to headers object/hash if present in notification data
    if data[:headers]
      headers = data[:headers]
      if headers.respond_to?(:[])
        ua = headers["HTTP_USER_AGENT"] || headers["User-Agent"] || headers["user-agent"]
        return sanitize_string(ua)[0..200]
      elsif headers.respond_to?(:to_h)
        h = begin
          headers.to_h
        rescue
          {}
        end
        ua = h["HTTP_USER_AGENT"] || h["User-Agent"] || h["user-agent"]
        return sanitize_string(ua)[0..200]
      end
    end

    # Fallback to env hash if present in notification data
    if data[:env].is_a?(Hash)
      ua = data[:env]["HTTP_USER_AGENT"]
      return sanitize_string(ua)[0..200]
    end

    ""
  rescue
    ""
  end
rescue
  ""
end

.sanitize_string(str) ⇒ Object 



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# File 'lib/dead_bro/subscriber.rb', line 294

def self.sanitize_string(str)
  str.to_s.gsub("\x00", "")
end

.sensitive_key?(key) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/dead_bro/subscriber.rb', line 304

def self.sensitive_key?(key)
  SENSITIVE_SEGMENT_RE.match?(key.to_s)
end

.sql_count(data) ⇒ Object 



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# File 'lib/dead_bro/subscriber.rb', line 395

def self.sql_count(data)
  # Count SQL queries from the payload if available
  if data[:sql_count]
    data[:sql_count]
  elsif defined?(ActiveRecord) && ActiveRecord::Base.connection
    # Try to get from ActiveRecord connection
    begin
      ActiveRecord::Base.connection.query_cache.size
    rescue
      0
    end
  else
    0
  end
rescue
  0
end

.subscribe!(client: Client.new) ⇒ Object 



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# File 'lib/dead_bro/subscriber.rb', line 10

def self.subscribe!(client: Client.new)
  ActiveSupport::Notifications.subscribe(EVENT_NAME) do |name, started, finished, _unique_id, data|
    # When disabled remotely, fire a heartbeat at most once per minute so the gem
    # can detect when tracking has been re-enabled, then skip all tracking.
    unless DeadBro.configuration.enabled
      client.post_heartbeat if DeadBro.configuration.heartbeat_due?
      drain_request_tracking
      next
    end

    if DeadBro.configuration.skip_tracking?
      client.post_heartbeat if DeadBro.configuration.heartbeat_due?
      drain_request_tracking
      next
    end

    # Skip excluded controllers or controller#action pairs
    # Also check exclusive_controller_actions - if defined, only track those
    notification = data.is_a?(Hash) ? data : {}
    controller_name = notification[:controller].to_s
    action_name = notification[:action].to_s
    begin
      if DeadBro.configuration.excluded_controller?(controller_name, action_name)
        drain_request_tracking
        next
      end
      unless DeadBro.configuration.exclusive_controller?(controller_name, action_name)
        drain_request_tracking
        next
      end
    rescue
      drain_request_tracking
      next
    end

    has_error = data[:exception] || data[:exception_object]
    request_type_key = "#{controller_name}##{action_name}"
    # Errors always ship regardless of sampling (this is what the docs promise).
    unless has_error || DeadBro.configuration.should_sample?(request_type_key)
      drain_request_tracking
      next
    end

    duration_ms = ((finished - started) * 1000.0).round(2)

    # Time spent in Rack middleware before ActionController took over (routing, session, auth, etc.)
    rack_start = Thread.current[DeadBro::TRACKING_START_TIME_KEY]
    rack_duration_ms = rack_start ? ([((started - rack_start) * 1000.0), 0].max).round(2) : nil

    # Stop SQL tracking and get collected queries (this was started by the request)
    sql_queries = DeadBro::SqlSubscriber.stop_request_tracking

    # Stop cache, redis, and elasticsearch tracking
    cache_events = defined?(DeadBro::CacheSubscriber) ? DeadBro::CacheSubscriber.stop_request_tracking : []
    redis_events = defined?(DeadBro::RedisSubscriber) ? DeadBro::RedisSubscriber.stop_request_tracking : []
    elasticsearch_events = defined?(DeadBro::ElasticsearchSubscriber) ? DeadBro::ElasticsearchSubscriber.stop_request_tracking : []

    # Stop DB connection pool wait tracking
    db_connection_stats = defined?(DeadBro::DbConnectionSubscriber) ? DeadBro::DbConnectionSubscriber.stop_request_tracking : {}

    # Stop GC pressure tracking — diff minor/major runs, objects allocated, GC time
    gc_pressure = defined?(DeadBro::GcTracker) ? DeadBro::GcTracker.stop_request_tracking : {}

    # Stop AR object instantiation tracking
    ar_instantiation_count = defined?(DeadBro::ArObjectTracker) ? DeadBro::ArObjectTracker.stop_request_tracking : nil

    # Stop CPU time tracking — thread CPU time consumed by this request
    cpu_time_ms = defined?(DeadBro::CpuTracker) ? DeadBro::CpuTracker.stop_request_tracking : nil

    # Stop view rendering tracking and get collected view events
    view_events = DeadBro::ViewRenderingSubscriber.stop_request_tracking
    view_performance = DeadBro::ViewRenderingSubscriber.analyze_view_performance(view_events)

    # Per-phase allocation attribution (under memory tracking) — which phase
    # allocated the request's objects (sql / view / elasticsearch).
    allocation_phases = if DeadBro.configuration.memory_tracking_enabled && defined?(DeadBro::MemoryPhaseTracker)
      DeadBro::MemoryPhaseTracker.stop_request_tracking
    else
      {}
    end

    # Stop memory tracking and get collected memory data. The decision to do
    # heavy allocation tracking was made (and sampled) at request start.
    if Thread.current[:dead_bro_alloc_active] && defined?(DeadBro::MemoryTrackingSubscriber)
      detailed_memory = DeadBro::MemoryTrackingSubscriber.stop_request_tracking
      memory_performance = DeadBro::MemoryTrackingSubscriber.analyze_memory_performance(detailed_memory)

      # Allocation-source + by-bytes-type diagnostics. Read the trace data
      # before stopping the sampler (stop clears the source locations).
      if defined?(DeadBro::AllocationSourceSampler)
        growth = (detailed_memory[:memory_after].to_f - detailed_memory[:memory_before].to_f)
        source_analysis = DeadBro::AllocationSourceSampler.analyze(memory_growth_mb: growth)
        DeadBro::AllocationSourceSampler.stop
        if source_analysis.is_a?(Hash) && source_analysis.any?
          memory_performance[:allocation_sources] = source_analysis[:by_source]
          memory_performance[:memsize_by_type] = source_analysis[:by_type_bytes]
          memory_performance[:allocation_sample_rate] = source_analysis[:sample_rate]
          memory_performance[:allocation_sources_skipped] = source_analysis[:skipped] if source_analysis[:skipped]
        end
      end

      # Keep memory_events compact and user-friendly (no large raw arrays)
      memory_events = {
        memory_before: detailed_memory[:memory_before],
        memory_after: detailed_memory[:memory_after],
        duration_seconds: detailed_memory[:duration_seconds],
        allocations_count: (detailed_memory[:allocations] || []).length,
        memory_snapshots_count: (detailed_memory[:memory_snapshots] || []).length,
        large_objects_count: (detailed_memory[:large_objects] || []).length
      }
    else
      lightweight_memory = DeadBro::LightweightMemoryTracker.stop_request_tracking
      # Separate raw readings from derived performance metrics to avoid duplicating data
      memory_events = {
        memory_before: lightweight_memory[:memory_before],
        memory_after: lightweight_memory[:memory_after]
      }
      memory_performance = {
        memory_growth_mb: lightweight_memory[:memory_growth_mb],
        gc_count_increase: lightweight_memory[:gc_count_increase],
        heap_pages_increase: lightweight_memory[:heap_pages_increase],
        duration_seconds: lightweight_memory[:duration_seconds]
      }
    end

    # Record memory sample for leak detection (only if memory tracking enabled)
    if DeadBro.configuration.memory_tracking_enabled
      DeadBro::MemoryLeakDetector.record_memory_sample({
        memory_usage: memory_usage_mb,
        gc_count: gc_stats[:count],
        heap_pages: gc_stats[:heap_allocated_pages],
        object_count: gc_stats[:heap_live_slots],
        request_id: data[:request_id],
        controller: data[:controller],
        action: data[:action]
      })
    end

    # Report exceptions attached to this action (e.g. controller/view errors)
    if data[:exception] || data[:exception_object]
      begin
        exception_class, exception_message = data[:exception] if data[:exception]
        exception_obj = data[:exception_object]
        backtrace = Array(exception_obj&.backtrace).first(50)

        error_payload = {
          controller: data[:controller],
          action: data[:action],
          format: data[:format],
          method: data[:method],
          path: safe_path(data),
          status: data[:status],
          duration_ms: duration_ms,
          rails_env: DeadBro.env,
          host: DeadBro.safe_hostname,
          process_kind: DeadBro.process_kind,
          params: safe_params(data),
          user_agent: safe_user_agent(data),
          user_id: extract_user_id(data),
          exception_class: exception_class || exception_obj&.class&.name,
          message: (exception_message || exception_obj&.message).to_s[0, 1000],
          backtrace: backtrace,
          fingerprint: compute_error_fingerprint(exception_obj),
          cause_chain: build_cause_chain(exception_obj),
          error: true,
          logs: DeadBro.logger.logs
        }

        event_name = (exception_class || exception_obj&.class&.name || "exception").to_s
        client.post_metric(event_name: event_name, payload: error_payload, force: true)
      rescue
      ensure
        next
      end
    end

    payload = {
      controller: data[:controller],
      action: data[:action],
      format: data[:format],
      method: data[:method],
      path: safe_path(data),
      status: data[:status],
      started_at: started.utc.iso8601(3),
      duration_ms: duration_ms,
      view_runtime_ms: data[:view_runtime],
      db_runtime_ms: data[:db_runtime],
      host: DeadBro.safe_hostname,
      rails_env: DeadBro.env,
      process_kind: DeadBro.process_kind,
      params: safe_params(data),
      user_agent: safe_user_agent(data),
      user_id: extract_user_id(data),
      memory_usage: memory_usage_mb,
      gc_stats: gc_stats,
      sql_count: sql_count(data),
      sql_queries: sql_queries,
      http_outgoing: Thread.current[:dead_bro_http_events] || [],
      cache_events: cache_events,
      redis_events: redis_events,
      elasticsearch_events: elasticsearch_events,
      cache_hits: cache_hits(data),
      cache_misses: cache_misses(data),
      view_events: view_events,
      view_performance: view_performance,
      memory_events: memory_events,
      memory_performance: memory_performance,
      allocation_phases: allocation_phases,
      rack_duration_ms: rack_duration_ms,
      queue_duration_ms: Thread.current[:dead_bro_queue_duration_ms],
      db_connection_wait_ms: db_connection_stats[:wait_ms],
      db_connection_checkouts: db_connection_stats[:checkouts],
      gc_pressure: gc_pressure,
      ar_instantiation_count: ar_instantiation_count,
      cpu_time_ms: cpu_time_ms,
      logs: DeadBro.logger.logs
    }
    # force: true — the sampling decision (global or per-request-type) was
    # already made above; client#post_metric must not re-roll it with the
    # global-only rate, which would silently override a per-type sample rate.
    client.post_metric(event_name: name, payload: payload, force: true)
  end
end

.truncate_value(value, max_str: 200, max_array: 20, max_hash_keys: 30) ⇒ Object

Recursively truncate values to reasonable sizes to avoid huge payloads, and redact values whose key looks sensitive at any nesting level.



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# File 'lib/dead_bro/subscriber.rb', line 310

def self.truncate_value(value, max_str: 200, max_array: 20, max_hash_keys: 30)
  case value
  when String
    sanitized = sanitize_string(value)
    (sanitized.length > max_str) ? sanitized[0, max_str] + "…" : sanitized
  when Numeric, TrueClass, FalseClass, NilClass
    value
  when Array
    value[0, max_array].map { |v| truncate_value(v, max_str: max_str, max_array: max_array, max_hash_keys: max_hash_keys) }
  when Hash
    entries = value.to_a[0, max_hash_keys]
    entries.each_with_object({}) do |(k, v), memo|
      memo[k] = sensitive_key?(k) ? "[FILTERED]" : truncate_value(v, max_str: max_str, max_array: max_array, max_hash_keys: max_hash_keys)
    end
  else
    (value.to_s.length > max_str) ? value.to_s[0, max_str] + "…" : value.to_s
  end
end