Class: OpenTelemetry::Baggage::Propagation::TextMapExtractor

Inherits:
Object
  • Object
show all
Includes:
Context::Propagation::DefaultGetter
Defined in:
lib/opentelemetry/baggage/propagation/text_map_extractor.rb

Overview

Extracts baggage from carriers in the W3C Baggage format

Instance Method Summary collapse

Methods included from Context::Propagation::DefaultGetter

#default_getter

Constructor Details

#initialize(baggage_key: 'baggage') ⇒ TextMapExtractor

Returns a new TextMapExtractor that extracts context using the specified header key

Parameters:

  • baggage_key (String) (defaults to: 'baggage') —

    The baggage header key used in the carrier



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# File 'lib/opentelemetry/baggage/propagation/text_map_extractor.rb', line 22

def initialize(baggage_key: 'baggage')
  @baggage_key = baggage_key
end

Instance Method Details

#extract(carrier, context, &getter) {|Carrier, String| ... } ⇒ Context

Extract remote baggage from the supplied carrier. If extraction fails, the original context will be returned

Parameters:

  • carrier (Carrier) —

    The carrier to get the header from

  • context (Context) —

    The context to be updated with extracted baggage

  • getter (optional Callable) —

    An optional callable that takes a carrier and a key and returns the value associated with the key. If omitted the default getter will be used which expects the carrier to respond to [] and []=.

Yields:

  • (Carrier, String) —

    if an optional getter is provided, extract will yield the carrier and the header key to the getter.

Returns:

  • (Context) —

    context updated with extracted baggage, or the original context if extraction fails



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# File 'lib/opentelemetry/baggage/propagation/text_map_extractor.rb', line 38

def extract(carrier, context, &getter)
  getter ||= default_getter
  header = getter.call(carrier, @baggage_key)

  entries = header.gsub(/\s/, '').split(',')

  baggage = entries.each_with_object({}) do |entry, memo|
    # The ignored variable below holds properties as per the W3C spec.
    # OTel is not using them currently, but they might be used for
    # metadata in the future
    kv, = entry.split(';', 2)
    k, v = kv.split('=').map!(&CGI.method(:unescape))
    memo[k] = v
  end

  context.set_value(ContextKeys.baggage_key, baggage)
rescue StandardError
  context
end