Class: Datadog::Profiling::Pprof::Template

Inherits:
Object
  • Object
show all
Defined in:
lib/ddtrace/profiling/pprof/template.rb

Overview

Converts a collection of profiling events into a Perftools::Profiles::Profile

Defined Under Namespace

Classes: NoProfilingEventConversionError, UnknownSampleTypeMappingError

Constant Summary collapse

DEFAULT_MAPPINGS = 
{
  Events::StackSample => Pprof::StackSample
}.freeze

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(mappings) ⇒ Template

Returns a new instance of Template.



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# File 'lib/ddtrace/profiling/pprof/template.rb', line 35

def initialize(mappings)
  @builder = Builder.new
  @converters = Hash.new { |_h, event_class| raise NoProfilingEventConversionError, event_class }
  @sample_type_mappings = Hash.new { |_h, type| raise UnknownSampleTypeMappingError, type }

  # Add default mapping
  builder.mappings.fetch($PROGRAM_NAME, &builder.method(:build_mapping))

  # Combine all sample types from each converter class
  types = mappings.values.each_with_object({}) do |converter_class, t|
    t.merge!(converter_class.sample_value_types)
  end

  # Build the sample types into sample type objects
  types.each do |type_name, type_args|
    index = nil

    sample_type = builder.sample_types.fetch(*type_args) do |id, type, unit|
      index = id
      builder.build_value_type(type, unit)
    end

    # Create mapping between the type and index to which its assigned.
    # Do this for faster lookup while building profile sample values.
    sample_type_mappings[type_name] = index || builder.sample_types.messages.index(sample_type)
  end

  # Freeze them so they can't be modified.
  # We don't want the number of sample types to vary between samples within the same profile.
  builder.sample_types.freeze
  sample_type_mappings.freeze

  # Add converters
  mappings.each do |event_class, converter_class|
    converters[event_class] = converter_class.new(builder, sample_type_mappings)
  end

  converters.freeze
end

Instance Attribute Details

#builder ⇒ Object (readonly)

Returns the value of attribute builder.



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# File 'lib/ddtrace/profiling/pprof/template.rb', line 18

def builder
  @builder
end

#converters ⇒ Object (readonly)

Returns the value of attribute converters.



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# File 'lib/ddtrace/profiling/pprof/template.rb', line 18

def converters
  @converters
end

#sample_type_mappings ⇒ Object (readonly)

Returns the value of attribute sample_type_mappings.



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# File 'lib/ddtrace/profiling/pprof/template.rb', line 18

def sample_type_mappings
  @sample_type_mappings
end

Class Method Details

.for_event_classes(event_classes) ⇒ Object 



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# File 'lib/ddtrace/profiling/pprof/template.rb', line 23

def self.for_event_classes(event_classes)
  # Build a map of event class --> converter class
  mappings = event_classes.each_with_object({}) do |event_class, m|
    converter_class = DEFAULT_MAPPINGS[event_class]
    raise NoProfilingEventConversionError, event_class unless converter_class

    m[event_class] = converter_class
  end

  new(mappings)
end

Instance Method Details

#add_events!(event_class, events) ⇒ Object 



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# File 'lib/ddtrace/profiling/pprof/template.rb', line 75

def add_events!(event_class, events)
  converters[event_class].add_events!(events)
end

#debug_statistics ⇒ Object 



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# File 'lib/ddtrace/profiling/pprof/template.rb', line 79

def debug_statistics
  converters.values.map(&:debug_statistics).join(', ')
end

#to_pprof(start:, finish:) ⇒ Object 



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# File 'lib/ddtrace/profiling/pprof/template.rb', line 83

def to_pprof(start:, finish:)
  profile = builder.build_profile(start: start, finish: finish)
  data = builder.encode_profile(profile)
  types = sample_type_mappings.keys

  Payload.new(data, types)
end