Class: AppProfiler::Backend::VernierBackend

Inherits:
BaseBackend
  • Object
show all
Defined in:
lib/app_profiler/backend/vernier_backend.rb

Constant Summary collapse

DEFAULTS = 
{
  mode: :wall,
}.freeze
AVAILABLE_MODES = 
[
  :wall,
  :retained,
].freeze
PRIVATE_METADATA = 
[
  :started_at, # started_at uses a monotonic source, not realtime
].freeze

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from BaseBackend

#run, run_lock

Class Method Details

.name ⇒ Object 



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# File 'lib/app_profiler/backend/vernier_backend.rb', line 23

def name
  :vernier
end

Instance Method Details

#results ⇒ Object 



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# File 'lib/app_profiler/backend/vernier_backend.rb', line 63

def results
  vernier_profile = backend_results
  clear

  return unless vernier_profile

  # Store all vernier metadata
  meta = vernier_profile.meta.reject { |k, v| k == :user_metadata || v.nil? || PRIVATE_METADATA.include?(k) }
  meta.merge!(@metadata) if @metadata

  # Internal metadata takes precedence over user metadata, but store
  # everything in user metadata
  vernier_profile.meta[:user_metadata]&.merge!(meta)

  # HACK: - "data" is private, but we want to avoid serializing to JSON then
  # parsing back from JSON by just directly getting the hash
  data = ::Vernier::Output::Firefox.new(vernier_profile).send(:data)
  data[:meta][:mode] = @mode
  data[:meta][:vernierUserMetadata] ||= meta # for compatibility with < 1.7.0
  @mode = nil
  @metadata = nil

  BaseProfile.from_vernier(data)
rescue => error
  AppProfiler.logger.info(
    "[Profiler] failed to obtain the profile error_class=#{error.class} error_message=#{error.message}",
  )
  nil
end

#running? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/app_profiler/backend/vernier_backend.rb', line 93

def running?
  @collector != nil
end

#start(params = {}) ⇒ Object 



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# File 'lib/app_profiler/backend/vernier_backend.rb', line 28

def start(params = {})
  # Do not start the profiler if we already have a collector started somewhere else.
  return false if running?
  return false unless acquire_run_lock

  @mode = params.delete(:mode) || DEFAULTS[:mode]
  raise ArgumentError unless AVAILABLE_MODES.include?(@mode)

  if Gem.loaded_specs["vernier"].version < Gem::Version.new("1.7.0")
    @metadata = params.delete(:metadata)
  end
  clear

  @collector ||= ::Vernier::Collector.new(@mode, **params)
  @collector.start
rescue => error
  AppProfiler.logger.info(
    "[Profiler] failed to start the profiler error_class=#{error.class} error_message=#{error.message}",
  )
  release_run_lock
  # This is a boolean instead of nil to be consistent with the stackprof backend behaviour
  # boolean as well.
  false
end

#stop ⇒ Object 



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# File 'lib/app_profiler/backend/vernier_backend.rb', line 53

def stop
  return false unless running?

  @results = @collector&.stop
  @collector = nil
  !@results.nil?
ensure
  release_run_lock
end