Use exceptions to report shutdown result

Fixes #2406

opentelemetry-api/src/opentelemetry/util/exceptions.py

@@ -0,0 +1,32 @@
+# 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.
+
+
+class Failure(Exception):
+    "Exception raised when a function fails"
+
+    def __init__(self, method, exceptions):
+        super().__init__()
+        self._method = method
+        self._exceptions = exceptions
+
+    def __str__(self):
+        return (
+            f"{self._method} failed with the following exceptions: "
+            f"{self._exceptions}"
+        )
+
+
+class Timeout(Exception):
+    "Exception raised when a function times out"

opentelemetry-sdk/src/opentelemetry/sdk/_metrics/__init__.py

@@ -50,6 +50,7 @@
 from opentelemetry.sdk.resources import Resource
 from opentelemetry.sdk.util.instrumentation import InstrumentationInfo
 from opentelemetry.util._once import Once
+from opentelemetry.util.exceptions import Failure, Timeout
 
 _logger = getLogger(__name__)
 
@@ -315,25 +316,24 @@ def _shutdown():
 
         if not did_shutdown:
             _logger.warning("shutdown can only be called once")
-            return False
+            return
 
-        overall_result = True
+        metric_reader_errors = []
 
         for metric_reader in self._sdk_config.metric_readers:
-            metric_reader_result = metric_reader.shutdown()
+            try:
+                metric_reader.shutdown()
 
-            if not metric_reader_result:
-                _logger.warning(
-                    "MetricReader %s failed to shutdown", metric_reader
-                )
+            except (Failure, Timeout) as error:
 
-            overall_result = overall_result and metric_reader_result
+                metric_reader_errors.append(error)
 
         if self._atexit_handler is not None:
             unregister(self._atexit_handler)
             self._atexit_handler = None
 
-        return overall_result
+        if metric_reader_errors:
+            raise Failure("MeterProvider.shutdown", metric_reader_errors)
 
     def get_meter(
         self,

opentelemetry-sdk/src/opentelemetry/sdk/_metrics/export/__init__.py

@@ -30,6 +30,7 @@
 from opentelemetry.sdk._metrics.metric_reader import MetricReader
 from opentelemetry.sdk._metrics.point import AggregationTemporality, Metric
 from opentelemetry.util._once import Once
+from opentelemetry.util.exceptions import Failure
 
 _logger = logging.getLogger(__name__)
 
@@ -122,8 +123,8 @@ def _receive_metrics(self, metrics: Iterable[Metric]):
         with self._lock:
             self._metrics = list(metrics)
 
-    def shutdown(self) -> bool:
-        return True
+    def shutdown(self):
+        pass
 
 
 class PeriodicExportingMetricReader(MetricReader):
@@ -193,16 +194,19 @@ def _receive_metrics(self, metrics: Iterable[Metric]) -> None:
             _logger.exception("Exception while exporting metrics %s", str(e))
         detach(token)
 
-    def shutdown(self) -> bool:
-        def _shutdown():
-            self._shutdown = True
+    def shutdown(self):
+        try:
+
+            def _shutdown():
+                self._shutdown = True
 
-        did_set = self._shutdown_once.do_once(_shutdown)
-        if not did_set:
-            _logger.warning("Can't shutdown multiple times")
-            return False
+            did_set = self._shutdown_once.do_once(_shutdown)
+            if not did_set:
+                _logger.warning("Can't shutdown multiple times")
+                return
 
-        self._shutdown_event.set()
-        self._daemon_thread.join()
-        self._exporter.shutdown()
-        return True
+            self._shutdown_event.set()
+            self._daemon_thread.join()
+            self._exporter.shutdown()
+        except Exception as error:
+            raise Failure("PeriodicExporterMetricReader", [error])

opentelemetry-sdk/src/opentelemetry/sdk/_metrics/metric_reader.py

@@ -65,7 +65,7 @@ def _receive_metrics(self, metrics: Iterable[Metric]):
         """Called by `MetricReader.collect` when it receives a batch of metrics"""
 
     @abstractmethod
-    def shutdown(self) -> bool:
+    def shutdown(self):
         """Shuts down the MetricReader. This method provides a way
         for the MetricReader to do any cleanup required. A metric reader can
         only be shutdown once, any subsequent calls are ignored and return

opentelemetry-sdk/tests/metrics/test_in_memory_metric_reader.py

@@ -63,7 +63,7 @@ def test_converts_metrics_to_list(self):
 
     def test_shutdown(self):
         # shutdown should always be successful
-        self.assertTrue(InMemoryMetricReader().shutdown())
+        self.assertIsNone(InMemoryMetricReader().shutdown())
 
     def test_integration(self):
         reader = InMemoryMetricReader()

opentelemetry-sdk/tests/metrics/test_metrics.py

@@ -32,6 +32,7 @@
 from opentelemetry.sdk._metrics.point import AggregationTemporality
 from opentelemetry.sdk.resources import Resource
 from opentelemetry.test.concurrency_test import ConcurrencyTestBase, MockFunc
+from opentelemetry.util.exceptions import Failure
 
 
 class DummyMetricReader(MetricReader):
@@ -151,7 +152,9 @@ def test_shutdown(self):
 
         mock_metric_reader_0 = MagicMock(
             **{
-                "shutdown.return_value": False,
+                "shutdown.side_effect": Failure(
+                    "method", [ZeroDivisionError()]
+                ),
                 "__str__.return_value": "mock_metric_reader_0",
             }
         )
@@ -161,23 +164,31 @@ def test_shutdown(self):
             metric_readers=[mock_metric_reader_0, mock_metric_reader_1]
         )
 
-        with self.assertLogs(level=WARNING) as log:
-            self.assertFalse(meter_provider.shutdown())
-            self.assertEqual(
-                log.records[0].getMessage(),
-                "MetricReader mock_metric_reader_0 failed to shutdown",
-            )
+        with self.assertRaises(Failure) as error:
+            meter_provider.shutdown()
+
+        error = error.exception
+
+        self.assertIsInstance(error, Failure)
+        self.assertEqual(
+            str(error),
+            (
+                "MeterProvider.shutdown failed with the following exceptions:"
+                " [Failure('method', [ZeroDivisionError()])]"
+            ),
+        )
+
         mock_metric_reader_0.shutdown.assert_called_once()
         mock_metric_reader_1.shutdown.assert_called_once()
 
-        mock_metric_reader_0 = Mock(**{"shutdown.return_value": True})
-        mock_metric_reader_1 = Mock(**{"shutdown.return_value": True})
+        mock_metric_reader_0 = Mock()
+        mock_metric_reader_1 = Mock()
 
         meter_provider = MeterProvider(
             metric_readers=[mock_metric_reader_0, mock_metric_reader_1]
         )
 
-        self.assertTrue(meter_provider.shutdown())
+        self.assertIsNone(meter_provider.shutdown())
         mock_metric_reader_0.shutdown.assert_called_once()
         mock_metric_reader_1.shutdown.assert_called_once()