Add MeterProvider and Meter to the SDK

Fixes open-telemetry#2200

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

@@ -0,0 +1,169 @@
+# 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.
+
+# pylint: disable=function-redefined,too-many-ancestors
+
+from atexit import register
+from logging import getLogger
+from typing import Optional
+
+from opentelemetry.metrics import Meter, MeterProvider
+from opentelemetry.metrics.instrument import (
+    Counter,
+    Histogram,
+    ObservableCounter,
+    ObservableGauge,
+    ObservableUpDownCounter,
+    UpDownCounter,
+)
+from opentelemetry.sdk.metrics.api import MetricExporter, MetricReader, View
+from opentelemetry.sdk.resources import Resource
+from opentelemetry.sdk.util.instrumentation import InstrumentationInfo
+
+_logger = getLogger(__name__)
+
+
+class Meter(Meter):
+    def __init__(self, instrumentation_info: InstrumentationInfo):
+        super().__init__(instrumentation_info)
+        self._instrumentation_info = instrumentation_info
+        self._meter_provider = None
+
+    def create_counter(self, name, unit=None, description=None) -> Counter:
+        pass
+
+    def create_up_down_counter(
+        self, name, unit=None, description=None
+    ) -> UpDownCounter:
+        pass
+
+    def create_observable_counter(
+        self, name, callback, unit=None, description=None
+    ) -> ObservableCounter:
+        pass
+
+    def create_histogram(self, name, unit=None, description=None) -> Histogram:
+        pass
+
+    def create_observable_gauge(
+        self, name, callback, unit=None, description=None
+    ) -> ObservableGauge:
+        pass
+
+    def create_observable_up_down_counter(
+        self, name, callback, unit=None, description=None
+    ) -> ObservableUpDownCounter:
+        pass
+
+
+class MeterProvider(MeterProvider):
+    """See `opentelemetry.metrics.Provider`."""
+
+    def __init__(
+        self,
+        resource: Resource = Resource.create({}),
+        shutdown_on_exit: bool = True,
+    ):
+        self._resource = resource
+        self._atexit_handler = None
+
+        if shutdown_on_exit:
+            self._atexit_handler = register(self.shutdown)
+
+        self._metric_readers = []
+        self._metric_exporters = []
+        self._views = []
+        self._shutdown = False
+
+    @property
+    def metric_readers(self):
+        return self._metric_readers
+
+    @property
+    def metric_exporters(self):
+        return self._metric_exporters
+
+    @property
+    def views(self):
+        return self._views
+
+    @property
+    def resource(self) -> Resource:
+        return self._resource
+
+    def get_meter(
+        self,
+        name: str,
+        version: Optional[str] = None,
+        schema_url: Optional[str] = None,
+    ) -> Meter:
+        meter = Meter(InstrumentationInfo(name, version, schema_url))
+
+        meter._meter_provider = self  # pylint: disable=protected-access
+
+        return meter
+
+    def shutdown(self):
+
+        if self._shutdown:
+            _logger.warning("shutdown can only be called once")
+            return False
+
+        result = True
+
+        for metric_reader in self._metric_readers:
+            result = result and metric_reader.shutdown()
+
+        for metric_exporter in self._metric_exporters:
+            result = result and metric_exporter.shutdown()
+
+        self._shutdown = True
+
+        return result
+
+    def force_flush(self) -> bool:
+        result = True
+
+        for metric_reader in self._metric_readers:
+            result = result and metric_reader.force_flush()
+
+        for metric_exporter in self._metric_exporters:
+            result = result and metric_exporter.force_flush()
+
+        return result
+
+    def register_metric_reader(self, metric_reader: "MetricReader") -> None:
+        self._metric_readers.append(metric_reader)
+
+    def register_metric_exporter(
+        self, metric_exporter: "MetricExporter"
+    ) -> None:
+        self._metric_exporters.append(metric_exporter)
+
+    def register_view(self, view: "View") -> None:
+        self._views.append(view)
+
+
+class MetricReader(MetricReader):
+    def collect(self):
+        pass
+
+
+class MetricExporter(MetricExporter):
+    def export(self):
+        pass
+
+
+class View(View):
+    pass

opentelemetry-sdk/src/opentelemetry/sdk/metrics/api.py

@@ -0,0 +1,48 @@
+# 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.
+
+# pylint: disable=function-redefined,too-many-ancestors
+
+from abc import ABC, abstractmethod
+from logging import getLogger
+
+_logger = getLogger(__name__)
+
+
+class MetricReader(ABC):
+    def __init__(self):
+        self._shutdown = False
+
+    @abstractmethod
+    def collect(self):
+        pass
+
+    def shutdown(self):
+        self._shutdown = True
+
+
+class MetricExporter(ABC):
+    def __init__(self):
+        self._shutdown = False
+
+    @abstractmethod
+    def export(self):
+        pass
+
+    def shutdown(self):
+        self._shutdown = True
+
+
+class View(ABC):
+    pass