import re

import uuid

_traceparent_header_format_re = re.compile(

"^[ \t]*([0-9a-f]{2})-([0-9a-f]{32})-([0-9a-f]{16})-([0-9a-f]{2})" "(-.*)?[ \t]*$"

)

class _EnvironHeaders(object):

def __init__(self, environ):

self.environ = environ

def get(self, key):

return self.environ.get("HTTP_" + key.replace("-", "_").upper())

class SpanContext(object):

def __init__(self, trace_id, span_id, recorded=False, parent=None):

self.trace_id = trace_id

self.span_id = span_id

self.recorded = recorded

self.parent = None

def __repr__(self):

return "%s(trace_id=%r, span_id=%r, recorded=%r)" % (

self.__class__.__name__,

self.trace_id,

self.span_id,

self.recorded,

)

@classmethod

def start_trace(cls, recorded=False):

return cls(

trace_id=uuid.uuid4().hex, span_id=uuid.uuid4().hex[16:], recorded=recorded

)

def new_span(self):

if self.trace_id is None:

return SpanContext.start_trace()

return SpanContext(

trace_id=self.trace_id,

span_id=uuid.uuid4().hex[16:],

parent=self,

recorded=self.recorded,

)

@classmethod

def continue_from_environ(cls, environ):

return cls.continue_from_headers(_EnvironHeaders(environ))

@classmethod

def continue_from_headers(cls, headers):

parent = cls.from_traceparent(headers.get("sentry-trace"))

if parent is None:

return cls.start_trace()

return parent.new_span()

def iter_headers(self):

yield "sentry-trace", self.to_traceparent()

@classmethod

def from_traceparent(cls, traceparent):

if not traceparent:

return None

match = _traceparent_header_format_re.match(traceparent)

if match is None:

return None

version, trace_id, span_id, trace_options, extra = match.groups()

if int(trace_id, 16) == 0 or int(span_id, 16) == 0:

return None

version = int(version, 16)

if version == 0:

if extra:

return None

elif version == 255:

return None

options = int(trace_options, 16)

return cls(trace_id=trace_id, span_id=span_id, recorded=options & 1 != 0)

def to_traceparent(self):

return "%02x-%s-%s-%02x" % (

0,

self.trace_id,

self.span_id,

self.recorded and 1 or 0,

)