test_threads.py

# Copyright The OpenTelemetry 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 concurrent.futures import (  # pylint: disable=no-name-in-module
    ThreadPoolExecutor,
)

from opentracing.ext import tags

# pylint: disable=import-error
from ..otel_ot_shim_tracer import MockTracer  # noqa: TID252
from ..testcase import OpenTelemetryTestCase  # noqa: TID252
from ..utils import get_logger, get_one_by_operation_name  # noqa: TID252
from .request_handler import RequestHandler

logger = get_logger(__name__)


class Client:
    def __init__(self, request_handler, executor):
        self.request_handler = request_handler
        self.executor = executor

    def send_task(self, message):
        request_context = {}

        def before_handler():
            self.request_handler.before_request(message, request_context)

        def after_handler():
            self.request_handler.after_request(message, request_context)

        self.executor.submit(before_handler).result()
        self.executor.submit(after_handler).result()

        return f"{message}::response"

    def send(self, message):
        return self.executor.submit(self.send_task, message)

    def send_sync(self, message, timeout=5.0):
        fut = self.executor.submit(self.send_task, message)
        return fut.result(timeout=timeout)


class TestThreads(OpenTelemetryTestCase):
    """
    There is only one instance of 'RequestHandler' per 'Client'. Methods of
    'RequestHandler' are executed concurrently in different threads which are
    reused (executor). Therefore we cannot use current active span and
    activate span. So one issue here is setting correct parent span.
    """

    def setUp(self):  # pylint: disable=invalid-name
        self.tracer = MockTracer()
        self.executor = ThreadPoolExecutor(max_workers=3)
        self.client = Client(RequestHandler(self.tracer), self.executor)

    def test_two_callbacks(self):
        response_future1 = self.client.send("message1")
        response_future2 = self.client.send("message2")

        self.assertEqual("message1::response", response_future1.result(5.0))
        self.assertEqual("message2::response", response_future2.result(5.0))

        spans = self.tracer.finished_spans()
        self.assertEqual(len(spans), 2)

        for span in spans:
            self.assertEqual(
                span.attributes.get(tags.SPAN_KIND, None),
                tags.SPAN_KIND_RPC_CLIENT,
            )

        self.assertNotSameTrace(spans[0], spans[1])
        self.assertIsNone(spans[0].parent)
        self.assertIsNone(spans[1].parent)

    def test_parent_not_picked(self):
        """Active parent should not be picked up by child."""

        with self.tracer.start_active_span("parent"):
            response = self.client.send_sync("no_parent")
            self.assertEqual("no_parent::response", response)

        spans = self.tracer.finished_spans()
        self.assertEqual(len(spans), 2)

        child_span = get_one_by_operation_name(spans, "send")
        self.assertIsNotNone(child_span)

        parent_span = get_one_by_operation_name(spans, "parent")
        self.assertIsNotNone(parent_span)

        # Here check that there is no parent-child relation.
        self.assertIsNotChildOf(child_span, parent_span)

    def test_bad_solution_to_set_parent(self):
        """Solution is bad because parent is per client and is not automatically
        activated depending on the context.
        """

        with self.tracer.start_active_span("parent") as scope:
            client = Client(
                # Pass a span context to be used ad the parent.
                RequestHandler(self.tracer, scope.span.context),
                self.executor,
            )
            response = client.send_sync("correct_parent")
            self.assertEqual("correct_parent::response", response)

        response = client.send_sync("wrong_parent")
        self.assertEqual("wrong_parent::response", response)

        spans = self.tracer.finished_spans()
        self.assertEqual(len(spans), 3)

        spans = sorted(spans, key=lambda x: x.start_time)
        parent_span = get_one_by_operation_name(spans, "parent")
        self.assertIsNotNone(parent_span)

        spans = [s for s in spans if s != parent_span]
        self.assertEqual(len(spans), 2)
        for span in spans:
            self.assertIsChildOf(span, parent_span)