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# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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from threading import Lock
import time
import opentracing
from opentracing import Format, Tracer
from opentracing import UnsupportedFormatException
from opentracing.scope_managers import ThreadLocalScopeManager
from .context import SpanContext
from .span import MockSpan
class MockTracer(Tracer):
"""MockTracer makes it easy to test the semantics of OpenTracing
instrumentation.
By using a MockTracer as a :class:`~opentracing.Tracer` implementation
for tests, a developer can assert that :class:`~opentracing.Span`
properties and relationships with other
**Spans** are defined as expected by instrumentation code.
By default, MockTracer registers propagators for :attr:`Format.TEXT_MAP`,
:attr:`Format.HTTP_HEADERS` and :attr:`Format.BINARY`. The user should
call :func:`register_propagator()` for each additional inject/extract
format.
"""
def __init__(self, scope_manager=None):
"""Initialize a MockTracer instance."""
scope_manager = ThreadLocalScopeManager() \
if scope_manager is None else scope_manager
super(MockTracer, self).__init__(scope_manager)
self._propagators = {}
self._finished_spans = []
self._spans_lock = Lock()
# Simple-as-possible (consecutive for repeatability) id generation.
self._next_id = 0
self._next_id_lock = Lock()
self._register_required_propagators()
def register_propagator(self, format, propagator):
"""Register a propagator with this MockTracer.
:param string format: a :class:`~opentracing.Format`
identifier like :attr:`~opentracing.Format.TEXT_MAP`
:param **Propagator** propagator: a **Propagator** instance to handle
inject/extract calls involving `format`
"""
self._propagators[format] = propagator
def _register_required_propagators(self):
from .text_propagator import TextPropagator
from .binary_propagator import BinaryPropagator
self.register_propagator(Format.TEXT_MAP, TextPropagator())
self.register_propagator(Format.HTTP_HEADERS, TextPropagator())
self.register_propagator(Format.BINARY, BinaryPropagator())
def finished_spans(self):
"""Return a copy of all finished **Spans** started by this MockTracer
(since construction or the last call to :meth:`~MockTracer.reset()`)
:rtype: list
:return: a copy of the finished **Spans**.
"""
with self._spans_lock:
return list(self._finished_spans)
def reset(self):
"""Clear the finished **Spans** queue.
Note that this does **not** have any effect on **Spans** created by
MockTracer that have not finished yet; those
will still be enqueued in :meth:`~MockTracer.finished_spans()`
when they :func:`finish()`.
"""
with self._spans_lock:
self._finished_spans = []
def _append_finished_span(self, span):
with self._spans_lock:
self._finished_spans.append(span)
def _generate_id(self):
with self._next_id_lock:
self._next_id += 1
return self._next_id
def start_active_span(self,
operation_name,
child_of=None,
references=None,
tags=None,
start_time=None,
ignore_active_span=False,
finish_on_close=True):
# create a new Span
span = self.start_span(
operation_name=operation_name,
child_of=child_of,
references=references,
tags=tags,
start_time=start_time,
ignore_active_span=ignore_active_span,
)
return self.scope_manager.activate(span, finish_on_close)
def start_span(self,
operation_name=None,
child_of=None,
references=None,
tags=None,
start_time=None,
ignore_active_span=False):
start_time = time.time() if start_time is None else start_time
# See if we have a parent_ctx in `references`
parent_ctx = None
if child_of is not None:
parent_ctx = (
child_of if isinstance(child_of, opentracing.SpanContext)
else child_of.context)
elif references is not None and len(references) > 0:
# TODO only the first reference is currently used
parent_ctx = references[0].referenced_context
# retrieve the active SpanContext
if not ignore_active_span and parent_ctx is None:
scope = self.scope_manager.active
if scope is not None:
parent_ctx = scope.span.context
# Assemble the child ctx
ctx = SpanContext(span_id=self._generate_id())
if parent_ctx is not None:
if parent_ctx._baggage is not None:
ctx._baggage = parent_ctx._baggage.copy()
ctx.trace_id = parent_ctx.trace_id
else:
ctx.trace_id = self._generate_id()
# Tie it all together
return MockSpan(
self,
operation_name=operation_name,
context=ctx,
parent_id=(None if parent_ctx is None else parent_ctx.span_id),
tags=tags,
start_time=start_time)
def inject(self, span_context, format, carrier):
if format in self._propagators:
self._propagators[format].inject(span_context, carrier)
else:
raise UnsupportedFormatException()
def extract(self, format, carrier):
if format in self._propagators:
return self._propagators[format].extract(carrier)
else:
raise UnsupportedFormatException()
