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,
)

# pylint: disable=import-error
from ..otel_ot_shim_tracer import MockTracer  # noqa: TID252
from ..testcase import OpenTelemetryTestCase  # noqa: TID252


class TestThreads(OpenTelemetryTestCase):
    def setUp(self):  # pylint: disable=invalid-name
        self.tracer = MockTracer()
        # use max_workers=3 as a general example even if only one would suffice
        self.executor = ThreadPoolExecutor(max_workers=3)

    def test_main(self):
        # Start an isolated task and query for its result -and finish it-
        # in another task/thread
        span = self.tracer.start_span("initial")
        self.submit_another_task(span)

        self.executor.shutdown(True)

        spans = self.tracer.finished_spans()
        self.assertEqual(len(spans), 3)
        self.assertNamesEqual(spans, ["initial", "subtask", "task"])

        # task/subtask are part of the same trace,
        # and subtask is a child of task
        self.assertSameTrace(spans[1], spans[2])
        self.assertIsChildOf(spans[1], spans[2])

        # initial task is not related in any way to those two tasks
        self.assertNotSameTrace(spans[0], spans[1])
        self.assertEqual(spans[0].parent, None)
        self.assertEqual(spans[2].parent, None)

    def task(self, span):
        # Create a new Span for this task
        with self.tracer.start_active_span("task"):
            with self.tracer.scope_manager.activate(span, True):
                # Simulate work strictly related to the initial Span
                pass

            # Use the task span as parent of a new subtask
            with self.tracer.start_active_span("subtask"):
                pass

    def submit_another_task(self, span):
        self.executor.submit(self.task, span)