How to use the opencensus.trace.propagation.trace_context_http_header_format.TraceContextPropagator function in opencensus

def test_from_headers_tracestate_limit(self):
        propagator = trace_context_http_header_format.\
            TraceContextPropagator()

        span_context = propagator.from_headers({
            'traceparent':
            '00-12345678901234567890123456789012-1234567890123456-00',
            'tracestate':
            ','.join([
                'a00=0,a01=1,a02=2,a03=3,a04=4,a05=5,a06=6,a07=7,a08=8,a09=9',
                'b00=0,b01=1,b02=2,b03=3,b04=4,b05=5,b06=6,b07=7,b08=8,b09=9',
                'c00=0,c01=1,c02=2,c03=3,c04=4,c05=5,c06=6,c07=7,c08=8,c09=9',
                'd00=0,d01=1,d02=2',
            ]),
        })

        self.assertFalse(span_context.tracestate)

def test_constructor_default(self):
        from opencensus.trace import print_exporter
        from opencensus.trace.propagation \
            import trace_context_http_header_format
        from opencensus.trace.samplers import ProbabilitySampler
        from opencensus.trace.span_context import SpanContext
        from opencensus.trace.tracers import noop_tracer

        tracer = tracer_module.Tracer()

        assert isinstance(tracer.span_context, SpanContext)
        assert isinstance(tracer.sampler, ProbabilitySampler)
        assert isinstance(tracer.exporter, print_exporter.PrintExporter)
        assert isinstance(
            tracer.propagator,
            trace_context_http_header_format.TraceContextPropagator)
        assert isinstance(tracer.tracer, noop_tracer.NoopTracer)

def test_header_match(self):
        propagator = trace_context_http_header_format.\
            TraceContextPropagator()

        trace_id = '12345678901234567890123456789012'
        span_id = '1234567890123456'

        # Trace option is not enabled.
        span_context = propagator.from_headers({
            'traceparent':
            '00-12345678901234567890123456789012-1234567890123456-00',
        })

        self.assertEqual(span_context.trace_id, trace_id)
        self.assertEqual(span_context.span_id, span_id)
        self.assertFalse(span_context.trace_options.enabled)

        # Trace option is enabled.

def test_from_headers_empty(self):
        from opencensus.trace.span_context import SpanContext

        propagator = trace_context_http_header_format.\
            TraceContextPropagator()

        span_context = propagator.from_headers({})

        self.assertTrue(isinstance(span_context, SpanContext))

def test_to_headers_with_empty_tracestate(self):
        from opencensus.trace import span_context
        from opencensus.trace import trace_options
        from opencensus.trace.tracestate import Tracestate

        propagator = trace_context_http_header_format.\
            TraceContextPropagator()

        trace_id = '12345678901234567890123456789012'
        span_id_hex = '1234567890123456'
        span_context = span_context.SpanContext(
            trace_id=trace_id,
            span_id=span_id_hex,
            tracestate=Tracestate(),
            trace_options=trace_options.TraceOptions('1'))

        headers = propagator.to_headers(span_context)

        self.assertTrue('traceparent' in headers)
        self.assertEqual(headers['traceparent'], '00-{}-{}-01'.format(
            trace_id, span_id_hex))

def get_tracer_propagator():
    global _tracer_propagator

    if _tracer_propagator is None:
        settings_ = getattr(settings, 'OPENCENSUS', {})
        settings_ = settings_.get('TRACE', {})

        _tracer_propagator = settings_.get('PROPAGATOR', None) or \
            trace_context_http_header_format.TraceContextPropagator()
        if isinstance(_tracer_propagator, str):
            _tracer_propagator = configuration.load(_tracer_propagator)

    return _tracer_propagator

def link(cls, headers):
        # type: (Dict[str, str]) -> None
        """
        Given a dictionary, extracts the context and links the context to the current tracer.

        :param headers: A key value pair dictionary
        :type headers: dict
        """
        ctx = trace_context_http_header_format.TraceContextPropagator().from_headers(headers)
        current_span = cls.get_current_span()
        current_span.add_link(Link(ctx.trace_id, ctx.span_id))

self.get_response = get_response
        settings = getattr(django.conf.settings, 'OPENCENSUS', {})
        settings = settings.get('TRACE', {})

        self.sampler = (settings.get('SAMPLER', None)
                        or samplers.ProbabilitySampler())
        if isinstance(self.sampler, six.string_types):
            self.sampler = configuration.load(self.sampler)

        self.exporter = settings.get('EXPORTER', None) or \
            print_exporter.PrintExporter()
        if isinstance(self.exporter, six.string_types):
            self.exporter = configuration.load(self.exporter)

        self.propagator = settings.get('PROPAGATOR', None) or \
            trace_context_http_header_format.TraceContextPropagator()
        if isinstance(self.propagator, six.string_types):
            self.propagator = configuration.load(self.propagator)

        self.blacklist_paths = settings.get(BLACKLIST_PATHS, None)

        self.blacklist_hostnames = settings.get(BLACKLIST_HOSTNAMES, None)

        if django.VERSION >= (2,):  # pragma: NO COVER
            connection.execute_wrappers.append(_trace_db_call)

#
#     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 opencensus.trace import print_exporter, samplers
from opencensus.trace.propagation import trace_context_http_header_format

DEFAULT_PYRAMID_TRACER_CONFIG = {
    'SAMPLER': samplers.AlwaysOnSampler(),
    'EXPORTER': print_exporter.PrintExporter(),
    'PROPAGATOR': trace_context_http_header_format.TraceContextPropagator(),
    # https://cloud.google.com/appengine/docs/flexible/python/
    # how-instances-are-managed#health_checking
    'BLACKLIST_PATHS': ['_ah/health'],
}


class PyramidTraceSettings(object):
    def __init__(self, registry):
        self.settings = registry.settings.get('OPENCENSUS', {})
        self.settings = self.settings.get(
            'TRACE', DEFAULT_PYRAMID_TRACER_CONFIG)

        _set_default_configs(self.settings, DEFAULT_PYRAMID_TRACER_CONFIG)

    def __getattr__(self, attr):
        # If not in defaults, it is something we cannot parse.