Initial implementation of a global Tracer.

README.rst

@@ -55,7 +55,7 @@ Somewhere in your server's request handler code:
 .. code-block:: python
 
  def handle_request(request):
- span = before_request(request, opentracing.tracer)
+ span = before_request(request, opentracing.global_tracer())
  # store span in some request-local storage using Tracer.scope_manager,
  # using the returned `Scope` as Context Manager to ensure
  # `Span` will be cleared and (in this case) `Span.finish()` be called.
@@ -111,7 +111,7 @@ Somewhere in your service that's about to make an outgoing call:
  def before_http_request(request, current_span_extractor):
  op = request.operation
  parent_span = current_span_extractor()
- outbound_span = opentracing.tracer.start_span(
+ outbound_span = opentracing.global_tracer().start_span(
  operation_name=op,
  child_of=parent_span
  )
@@ -127,7 +127,7 @@ Somewhere in your service that's about to make an outgoing call:
  outbound_span.set_tag(tags.PEER_PORT, port)
 
  http_header_carrier = {}
- opentracing.tracer.inject(
+ opentracing.global_tracer().inject(
  span_context=outbound_span,
  format=Format.HTTP_HEADERS,
  carrier=http_header_carrier)

docs/api.rst

@@ -29,6 +29,10 @@ Classes
 
 Utility Functions
 -----------------
+.. autofunction:: opentracing.global_tracer
+
+.. autofunction:: opentracing.set_global_tracer
+
 .. autofunction:: opentracing.start_child_span
 
 .. autofunction:: opentracing.child_of

opentracing/__init__.py

@@ -32,4 +32,29 @@
 # Global variable that should be initialized to an instance of real tracer.
 # Note: it should be accessed via 'opentracing.tracer', not via
 # 'from opentracing import tracer', the latter seems to take a copy.
+# DEPRECATED, use global_tracer() and set_global_tracer() instead.
 tracer = Tracer()
+
+
+def global_tracer():
+ """Returns the global tracer.
+ The default value is an instance of :class:`opentracing.Tracer`
+
+ :rtype: :class:`Tracer`
+ :return: The global tracer instance.
+ """
+ return tracer
+
+
+def set_global_tracer(value):
+ """Sets the global tracer.
+ It is an error to pass ``None``.
+
+ :param value: the :class:`Tracer` used as global instance.
+ :type value: :class:`Tracer`
+ """
+ if value is None:
+ raise ValueError('The global Tracer tracer cannot be None')
+
+ global tracer
+ tracer = value

tests/test_globaltracer.py

@@ -0,0 +1,38 @@
+# Copyright The OpenTracing Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from __future__ import absolute_import
+import pytest
+import mock
+import opentracing
+
+
+def test_opentracing_tracer():
+ assert opentracing.tracer is opentracing.global_tracer()
+ assert isinstance(opentracing.global_tracer(), opentracing.Tracer)
+
+
+@mock.patch('opentracing.tracer')
+def test_set_global_tracer(mock_obj):
+ tracer = mock.Mock()
+ opentracing.set_global_tracer(tracer)
+ assert opentracing.global_tracer() is tracer
+
+ opentracing.set_global_tracer(mock_obj)
+ assert opentracing.global_tracer() is mock_obj
+
+
+def test_register_none():
+ with pytest.raises(ValueError):
+ opentracing.set_global_tracer(None)