def extract(
self,
carrier: CarrierT,
context: Optional[Context] = None,
getter: Getter = default_getter,
) -> Context:
if context is None:
context = Context()
traceid = _extract_identifier(
getter.get(carrier, OT_TRACE_ID_HEADER),
_valid_extract_traceid,
INVALID_TRACE_ID,
)
spanid = _extract_identifier(
getter.get(carrier, OT_SPAN_ID_HEADER),
_valid_extract_spanid,
INVALID_SPAN_ID,
)
sampled = _extract_first_element(
getter.get(carrier, OT_SAMPLED_HEADER)
)
if sampled == "true":
traceflags = TraceFlags.SAMPLED
else:
traceflags = TraceFlags.DEFAULT
if traceid != INVALID_TRACE_ID and spanid != INVALID_SPAN_ID:
context = set_span_in_context(
NonRecordingSpan(
SpanContext(
trace_id=traceid,
span_id=spanid,
is_remote=True,
trace_flags=TraceFlags(traceflags),
)
),
context,
)
baggage = get_all(context) or {}
for key in getter.keys(carrier):
if not key.startswith(OT_BAGGAGE_PREFIX):
continue
baggage[
key[len(OT_BAGGAGE_PREFIX) :]
] = _extract_first_element(getter.get(carrier, key))
for key, value in baggage.items():
context = set_baggage(key, value, context)
return context
def _get_header_value(
getter: textmap.Getter, carrier: textmap.CarrierT,
) -> typing.Optional[str]:
# first try all lowercase header
header = getter.get(carrier, _TRACE_CONTEXT_HEADER_NAME)
if header:
return header[0]
# otherwise try to find in keys for mixed case
for key in getter.keys(carrier):
if key.lower() == _TRACE_CONTEXT_HEADER_NAME:
header = getter.get(carrier, key)
if header:
return header[0]
return None