text: #  BSD 3-Clause License
  #
  #  Copyright (c) 2019, Elasticsearch BV
  #  All rights reserved.
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  #  Redistribution and use in source and binary forms, with or without
  #  modification, are permitted provided that the following conditions are met:
  #
  #  * Redistributions of source code must retain the above copyright notice, this
  #    list of conditions and the following disclaimer.
  #
  #  * Redistributions in binary form must reproduce the above copyright notice,
  #    this list of conditions and the following disclaimer in the documentation
  #    and/or other materials provided with the distribution.
  #
  #  * Neither the name of the copyright holder nor the names of its
  #    contributors may be used to endorse or promote products derived from
  #    this software without specific prior written permission.
  #
  #  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  #  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  #  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  #  DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
  #  FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  #  DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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  #  CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  #  OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  #  OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  
  from elasticapm.conf import constants
  from elasticapm.instrumentation.packages.base import AbstractInstrumentedModule
  from elasticapm.traces import DroppedSpan, capture_span, execution_context
  from elasticapm.utils import default_ports
  from elasticapm.utils.disttracing import TracingOptions
  
  
  class Urllib3Instrumentation(AbstractInstrumentedModule):
      name = "urllib3"
  
      instrument_list = [
          ("urllib3.connectionpool", "HTTPConnectionPool.urlopen"),
          # packages that vendor or vendored urllib3 in the past
          ("requests.packages.urllib3.connectionpool", "HTTPConnectionPool.urlopen"),
          ("botocore.vendored.requests.packages.urllib3.connectionpool", "HTTPConnectionPool.urlopen"),
      ]
  
      def call(self, module, method, wrapped, instance, args, kwargs):
          if "method" in kwargs:
              method = kwargs["method"]
          else:
              method = args[0]
  
          headers = None
          if "headers" in kwargs:
              headers = kwargs["headers"]
              if headers is None:
                  headers = {}
                  kwargs["headers"] = headers
  
          host = instance.host
  
          if instance.port != default_ports.get(instance.scheme):
              host += ":" + str(instance.port)
  
          if "url" in kwargs:
              url = kwargs["url"]
          else:
              url = args[1]
  
          signature = method.upper() + " " + host
  
          # TODO: reconstruct URL more faithfully, e.g. include port
          url = instance.scheme + "://" + host + url
          transaction = execution_context.get_transaction()
  
          with capture_span(
              signature, span_type="external", span_subtype="http", extra={"http": {"url": url}}, leaf=True
          ) as span:
              # if urllib3 has been called in a leaf span, this span might be a DroppedSpan.
              leaf_span = span
              while isinstance(leaf_span, DroppedSpan):
                  leaf_span = leaf_span.parent
  
              if headers is not None:
                  # It's possible that there are only dropped spans, e.g. if we started dropping spans.
                  # In this case, the transaction.id is used
                  parent_id = leaf_span.id if leaf_span else transaction.id
                  trace_parent = transaction.trace_parent.copy_from(
                      span_id=parent_id, trace_options=TracingOptions(recorded=True)
                  )
                  headers[constants.TRACEPARENT_HEADER_NAME] = trace_parent.to_string()
              return wrapped(*args, **kwargs)
  
      def mutate_unsampled_call_args(self, module, method, wrapped, instance, args, kwargs, transaction):
          # since we don't have a span, we set the span id to the transaction id
          trace_parent = transaction.trace_parent.copy_from(
              span_id=transaction.id, trace_options=TracingOptions(recorded=False)
          )
          if "headers" in kwargs:
              headers = kwargs["headers"]
              if headers is None:
                  headers = {}
                  kwargs["headers"] = headers
              headers[constants.TRACEPARENT_HEADER_NAME] = trace_parent.to_string()
          return args, kwargs
  