Adds metric prototype

Fixes open-telemetry#1835

CHANGELOG.md

@@ -114,6 +114,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   ([#1877](https://github.com/open-telemetry/opentelemetry-python/pull/1877))
 - Added support for CreateKey functionality.
   ([#1853](https://github.com/open-telemetry/opentelemetry-python/pull/1853))
+- Add metrics
+  ([#1887](https://github.com/open-telemetry/opentelemetry-python/pull/1887))
 
 ### Changed
 - Updated get_tracer to return an empty string when passed an invalid name

docs/examples/metrics/grocery/README.rst

@@ -0,0 +1,10 @@
+Grocery
+=======
+
+This is the implementation of the grocery scenario.
+
+
+Useful links
+------------
+
+.. _Grocery: https://github.com/open-telemetry/oteps/blob/main/text/metrics/0146-metrics-prototype-scenarios.md#scenario-1-grocery

docs/examples/metrics/grocery/grocery.py

@@ -0,0 +1,94 @@
+# 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 opentelemetry.metrics import get_meter_provider
+from opentelemetry.sdk.metrics.export import ConsoleExporter
+
+exporter = ConsoleExporter()
+
+get_meter_provider().start_pipeline_equivalent(exporter, 5)
+
+meter = get_meter_provider().get_meter()
+
+
+order_counter = meter.create_counter(
+    name="orders",
+    description="number of orders",
+    unit="order",
+    value_type=int,
+)
+
+amount_counter = meter.create_counter(
+    name="amount",
+    description="amount paid",
+    unit="dollar",
+    value_type=int,
+)
+
+sold_items_counter = meter.create_counter(
+    name="sold items",
+    description="number of sold items",
+    unit="item",
+    value_type=int,
+)
+
+customers_in_store = meter.create_up_down_counter(
+    name="customers in store",
+    description="amount of customers present in store",
+    unit="customer",
+    value_type=int,
+)
+
+
+class GroceryStore:
+    def __init__(self, name):
+        self._name = name
+
+    def process_order(self, customer_name, potatoes=0, tomatoes=0):
+        order_counter.add(1, {"store": self._name, "customer": customer_name})
+
+        amount_counter.add(
+            (potatoes * 1) + (tomatoes * 3),
+            {"store": self._name, "customer": customer_name},
+        )
+
+        sold_items_counter.add(
+            potatoes,
+            {
+                "store": self._name,
+                "customer": customer_name,
+                "item": "potato",
+            },
+        )
+
+        sold_items_counter.add(
+            tomatoes,
+            {
+                "store": self._name,
+                "customer": customer_name,
+                "item": "tomato",
+            },
+        )
+
+    def enter_customer(self, customer_name, account_type):
+
+        customers_in_store.add(
+            1, {"store": self._name, "account_type": account_type}
+        )
+
+    def exit_customer(self, customer_name, account_type):
+
+        customers_in_store.add(
+            -1, {"store": self._name, "account_type": account_type}
+        )

docs/getting_started/otlpcollector_example.py

@@ -14,10 +14,13 @@
 
 # otcollector.py
 
-from opentelemetry import trace
+from opentelemetry import metrics, trace
+from opentelemetry.exporter.otlp.metrics_exporter import OTLPMetricsExporter
 from opentelemetry.exporter.otlp.proto.grpc.trace_exporter import (
     OTLPSpanExporter,
 )
+from opentelemetry.sdk.metrics import MeterProvider
+from opentelemetry.sdk.metrics.export import PushController
 from opentelemetry.sdk.trace import TracerProvider
 from opentelemetry.sdk.trace.export import BatchSpanProcessor
 

docs/sdk/sdk.rst

@@ -8,5 +8,6 @@ OpenTelemetry Python SDK
 
     resources
     trace
+    metrics
     error_handler
     environment_variables

exporter/opentelemetry-exporter-otlp-proto-grpc/src/opentelemetry/exporter/otlp/proto/grpc/exporter.py

@@ -126,7 +126,7 @@ def _translate_key_values(key: Text, value: Any) -> KeyValue:
     return KeyValue(key=key, value=_translate_value(value))
 
 
-def get_resource_data(
+def _get_resource_data(
     sdk_resource_instrumentation_library_data: Dict[
         SDKResource, ResourceDataT
     ],

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

@@ -0,0 +1,216 @@
+# 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=abstract-class-instantiated
+# pylint: disable=too-many-ancestors
+# pylint: disable=useless-super-delegation
+
+
+from abc import ABC, abstractmethod
+from functools import wraps
+from logging import getLogger
+from typing import cast
+
+from opentelemetry.environment_variables import OTEL_PYTHON_METER_PROVIDER
+from opentelemetry.metrics.instrument import (
+    Counter,
+    DefaultCounter,
+    DefaultHistogram,
+    DefaultObservableCounter,
+    DefaultObservableGauge,
+    DefaultObservableUpDownCounter,
+    DefaultUpDownCounter,
+    Histogram,
+    ObservableCounter,
+    ObservableGauge,
+    ObservableUpDownCounter,
+    UpDownCounter,
+)
+from opentelemetry.util._providers import _load_provider
+from opentelemetry.util.types import Attributes
+
+_logger = getLogger(__name__)
+
+
+class Measurement(ABC):
+    @abstractmethod
+    def __init__(self, value, **attributes: Attributes):
+        pass
+
+
+class DefaultMeasurement(Measurement):
+    def __init__(self, value, **attributes: Attributes):
+        super().__init__(value, **attributes)
+
+
+class Meter(ABC):
+
+    # FIXME make unit and description be "" if unit or description are None
+    @abstractmethod
+    def create_counter(self, name, unit=None, description=None) -> Counter:
+        pass
+
+    @abstractmethod
+    def create_up_down_counter(
+        self, name, unit=None, description=None
+    ) -> UpDownCounter:
+        pass
+
+    @abstractmethod
+    def create_observable_counter(
+        self, name, callback, unit=None, description=None
+    ) -> ObservableCounter:
+        pass
+
+    @abstractmethod
+    def create_histogram(self, name, unit=None, description=None) -> Histogram:
+        pass
+
+    @abstractmethod
+    def create_observable_gauge(
+        self, name, callback, unit=None, description=None
+    ) -> ObservableGauge:
+        pass
+
+    @abstractmethod
+    def create_observable_up_down_counter(
+        self, name, callback, unit=None, description=None
+    ) -> ObservableUpDownCounter:
+        pass
+
+    @staticmethod
+    def check_unique_name(checker):
+        def wrapper_0(method):
+            @wraps(method)
+            def wrapper_1(self, name, unit=None, description=None):
+                checker(self, name)
+                return method(self, name, unit=unit, description=description)
+
+            return wrapper_1
+
+        return wrapper_0
+
+
+class DefaultMeter(Meter):
+    def __init__(self):
+        self._instrument_names = set()
+
+    def _instrument_name_checker(self, name):
+
+        if name in self._instrument_names:
+            raise Exception("Instrument name {} has been used already")
+
+        self._instrument_names.add(name)
+
+    @Meter.check_unique_name(_instrument_name_checker)
+    def create_counter(self, name, unit=None, description=None) -> Counter:
+        return DefaultCounter(name, unit=unit, description=description)
+
+    @Meter.check_unique_name(_instrument_name_checker)
+    def create_up_down_counter(
+        self, name, unit=None, description=None
+    ) -> UpDownCounter:
+        return DefaultUpDownCounter(name, unit=unit, description=description)
+
+    @Meter.check_unique_name(_instrument_name_checker)
+    def create_observable_counter(
+        self, name, callback, unit=None, description=None
+    ) -> ObservableCounter:
+        return DefaultObservableCounter(
+            name,
+            callback,
+            unit=unit,
+            description=description,
+        )
+
+    @Meter.check_unique_name(_instrument_name_checker)
+    def create_histogram(self, name, unit=None, description=None) -> Histogram:
+        return DefaultHistogram(name, unit=unit, description=description)
+
+    @Meter.check_unique_name(_instrument_name_checker)
+    def create_observable_gauge(
+        self, name, callback, unit=None, description=None
+    ) -> ObservableGauge:
+        return DefaultObservableGauge(  # pylint: disable=abstract-class-instantiated
+            name,
+            callback,
+            unit=unit,
+            description=description,
+        )
+
+    @Meter.check_unique_name(_instrument_name_checker)
+    def create_observable_up_down_counter(
+        self, name, callback, unit=None, description=None
+    ) -> ObservableUpDownCounter:
+        return DefaultObservableUpDownCounter(  # pylint: disable=abstract-class-instantiated
+            name,
+            callback,
+            unit=unit,
+            description=description,
+        )
+
+
+class MeterProvider(ABC):
+    """
+    var
+    """
+
+    @abstractmethod
+    def get_meter(
+        self,
+        name,
+        version=None,
+        schema_url=None,
+    ) -> Meter:
+        """
+        vpas
+        """
+        pass
+
+
+class DefaultMeterProvider(MeterProvider):
+    def get_meter(
+        self,
+        name,
+        version=None,
+        schema_url=None,
+    ) -> Meter:
+        return DefaultMeter()
+
+
+_METER_PROVIDER = None
+
+
+def set_meter_provider(meter_provider: MeterProvider) -> None:
+    """Sets the current global :class:`~.MeterProvider` object."""
+    global _METER_PROVIDER  # pylint: disable=global-statement
+
+    if _METER_PROVIDER is not None:
+        _logger.warning("Overriding of current MeterProvider is not allowed")
+        return
+
+    _METER_PROVIDER = meter_provider
+
+
+def get_meter_provider() -> MeterProvider:
+    """Gets the current global :class:`~.MeterProvider` object."""
+    global _METER_PROVIDER  # pylint: disable=global-statement
+
+    if _METER_PROVIDER is None:
+        _METER_PROVIDER = cast(
+            "MeterProvider",
+            _load_provider(OTEL_PYTHON_METER_PROVIDER, "meter_provider"),
+        )
+
+    return _METER_PROVIDER