Class: Datadog::Tracing::Distributed::Baggage

Inherits:
Object
  • Object
show all
Defined in:
lib/datadog/tracing/distributed/baggage.rb

Overview

W3C Baggage propagator implementation. The baggage header is propagated through ‘baggage`.

See Also:

Constant Summary collapse

BAGGAGE_KEY = 
'baggage'
DD_TRACE_BAGGAGE_MAX_ITEMS = 
64
DD_TRACE_BAGGAGE_MAX_BYTES = 
8192
SAFE_CHARACTERS_KEY = 
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789$!#&'*+-.^_`|~"
SAFE_CHARACTERS_VALUE = 
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789$!#&'()*+-./:<>?@[]^_`{|}~"

Instance Method Summary collapse

Constructor Details

#initialize(fetcher:, baggage_key: BAGGAGE_KEY) ⇒ Baggage

Returns a new instance of Baggage.



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# File 'lib/datadog/tracing/distributed/baggage.rb', line 23

def initialize(
  fetcher:,
  baggage_key: BAGGAGE_KEY
)
  @baggage_key = baggage_key
  @fetcher = fetcher
end

Instance Method Details

#extract(data) ⇒ Object 



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# File 'lib/datadog/tracing/distributed/baggage.rb', line 67

def extract(data)
  fetcher = @fetcher.new(data)
  data = fetcher[@baggage_key]
  return unless data

  baggage = parse_baggage_header(fetcher[@baggage_key])
  return unless baggage

  TraceDigest.new(
    baggage: baggage,
  )
end

#inject!(digest, data) ⇒ Object 



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# File 'lib/datadog/tracing/distributed/baggage.rb', line 31

def inject!(digest, data)
  return if digest.nil? || digest.baggage.nil?

  baggage_items = digest.baggage.reject { |k, v| k.nil? || v.nil? }
  return if baggage_items.empty?

  begin
    if baggage_items.size > DD_TRACE_BAGGAGE_MAX_ITEMS
      ::Datadog.logger.warn('Baggage item limit exceeded, dropping excess items')
      baggage_items = baggage_items.first(DD_TRACE_BAGGAGE_MAX_ITEMS)
    end

    encoded_items = []
    total_size = 0

    baggage_items.each do |key, value|
      item = "#{encode_item(key, SAFE_CHARACTERS_KEY)}=#{encode_item(value, SAFE_CHARACTERS_VALUE)}"
      item_size = item.bytesize + (encoded_items.empty? ? 0 : 1) # +1 for comma if not first item
      if total_size + item_size > DD_TRACE_BAGGAGE_MAX_BYTES
        ::Datadog.logger.warn('Baggage header size exceeded, dropping excess items')
        break # stop adding items when size limit is reached
      end
      encoded_items << item
      total_size += item_size
    end

    # edge case where a single item is too large
    return if encoded_items.empty?

    header_value = encoded_items.join(',')
    data[@baggage_key] = header_value
  rescue => e
    ::Datadog.logger.warn("Failed to encode and inject baggage header: #{e.message}")
  end
end