Module: XRay::Facets::Helper

Included in:
AwsSDKPlugin::Handler, NetHttp::HTTPInstanceInterceptor, Rack::Middleware
Defined in:
lib/aws-xray-sdk/facets/helper.rb

Overview

Hepler functions shared for all external frameworks/libraries like make sampling decisions from incoming http requests etc.

Constant Summary collapse

TRACE_HEADER = 
'X-Amzn-Trace-Id'.freeze
TRACE_HEADER_PROXY = 
'HTTP_X_AMZN_TRACE_ID'.freeze

Instance Method Summary collapse

Instance Method Details

#construct_header(headers:) ⇒ TraceHeader

Construct a TraceHeader object from headers of the incoming request. This method should always return a TraceHeader object regardless of tracing header's presence in the incoming request.

Parameters:

  • headers (Hash) —

    Hash that contains X-Ray trace header key.

Returns:

  • (TraceHeader) —

    The new constructed trace header object.



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# File 'lib/aws-xray-sdk/facets/helper.rb', line 17

def construct_header(headers:)
  if v = headers[TRACE_HEADER_PROXY] || headers[TRACE_HEADER]
    TraceHeader.from_header_string header_str: v
  else
    TraceHeader.empty_header
  end
end

#prep_header_str(entity:) ⇒ Object

Prepares a X-Ray header string based on the provided Segment/Subsegment.



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# File 'lib/aws-xray-sdk/facets/helper.rb', line 44

def prep_header_str(entity:)
  TraceHeader.from_entity(entity: entity).header_string
end

#should_sample?(header_obj:, recorder:, sampling_req:, **args) ⇒ Boolean

The sampling decision coming from trace_header always has the highest precedence. If the trace_header doesn't contain sampling decision then it checks if sampling is enabled or not in the recorder. If not enbaled it returns 'true'. Otherwise it uses sampling rules to decide.

Returns:

  • (Boolean) 


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# File 'lib/aws-xray-sdk/facets/helper.rb', line 30

def should_sample?(header_obj:, recorder:, sampling_req:, **args)
  # check outside decision
  if i = header_obj.sampled
    !i.zero?
  # check sampling rules
  elsif recorder.sampling_enabled?
    recorder.sampler.sample_request?(sampling_req)
  # sample if no reason not to
  else
    true
  end
end