metrics api/sdk: Move "config" out from Meter into MeterProvider (open-telemetry#751)

lzchen · web-flow · commit 75a131194adc · 2020-06-04T10:02:37.000-07:00
diff --git a/docs/examples/basic_meter/basic_metrics.py b/docs/examples/basic_meter/basic_metrics.py
@@ -30,33 +30,17 @@
 
 stateful = True
 
-
-def usage(argv):
-    print("usage:")
-    print("{} [mode]".format(argv[0]))
-    print("mode: stateful (default) or stateless")
-
-
-if len(sys.argv) >= 2:
-    batcher_mode = sys.argv[1]
-    if batcher_mode not in ("stateful", "stateless"):
-        print("bad mode specified.")
-        usage(sys.argv)
-        sys.exit(1)
-    stateful = batcher_mode == "stateful"
-
 print(
     "Starting example, values will be printed to the console every 5 seconds."
 )
 
-
+# Stateful determines whether how metrics are collected: if true, metrics
+# accumulate over the process lifetime. If false, metrics are reset at the
+# beginning of each collection interval.
+metrics.set_meter_provider(MeterProvider(stateful))
 # The Meter is responsible for creating and recording metrics. Each meter has a
-# unique name, which we set as the module's name here. The second argument
-# determines whether how metrics are collected: if true, metrics accumulate
-# over the process lifetime. If false, metrics are reset at the beginning of
-# each collection interval.
-metrics.set_meter_provider(MeterProvider())
-meter = metrics.get_meter(__name__, batcher_mode == "stateful")
+# unique name, which we set as the module's name here.
+meter = metrics.get_meter(__name__)
 
 # Exporter to export metrics to the console
 exporter = ConsoleMetricsExporter()
diff --git a/docs/examples/basic_meter/observer.py b/docs/examples/basic_meter/observer.py
@@ -24,8 +24,6 @@
 from opentelemetry.sdk.metrics.export.batcher import UngroupedBatcher
 from opentelemetry.sdk.metrics.export.controller import PushController
 
-# Configure a stateful batcher
-batcher = UngroupedBatcher(stateful=True)
 metrics.set_meter_provider(MeterProvider())
 meter = metrics.get_meter(__name__)
 exporter = ConsoleMetricsExporter()
diff --git a/opentelemetry-api/CHANGELOG.md b/opentelemetry-api/CHANGELOG.md
@@ -2,6 +2,8 @@
 
 ## Unreleased
 
+- Move stateful from Meter to MeterProvider
+  ([#751](https://github.com/open-telemetry/opentelemetry-python/pull/751))
 - Rename Measure to ValueRecorder in metrics
   ([#761](https://github.com/open-telemetry/opentelemetry-python/pull/761))
 
diff --git a/opentelemetry-api/src/opentelemetry/metrics/__init__.py b/opentelemetry-api/src/opentelemetry/metrics/__init__.py
@@ -29,7 +29,7 @@
 """
 import abc
 from logging import getLogger
-from typing import Callable, Dict, Sequence, Tuple, Type, TypeVar
+from typing import Callable, Dict, Optional, Sequence, Tuple, Type, TypeVar
 
 from opentelemetry.util import _load_provider
 
@@ -195,7 +195,6 @@ class MeterProvider(abc.ABC):
     def get_meter(
         self,
         instrumenting_module_name: str,
-        stateful: bool = True,
         instrumenting_library_version: str = "",
     ) -> "Meter":
         """Returns a `Meter` for use by the given instrumentation library.
@@ -212,12 +211,6 @@ def get_meter(
                 E.g., instead of ``"requests"``, use
                 ``"opentelemetry.ext.requests"``.
 
-            stateful: True/False to indicate whether the meter will be
-                    stateful. True indicates the meter computes checkpoints
-                    from over the process lifetime. False indicates the meter
-                    computes checkpoints which describe the updates of a single
-                    collection period (deltas).
-
             instrumenting_library_version: Optional. The version string of the
                 instrumenting library.  Usually this should be the same as
                 ``pkg_resources.get_distribution(instrumenting_library_name).version``.
@@ -233,7 +226,6 @@ class DefaultMeterProvider(MeterProvider):
     def get_meter(
         self,
         instrumenting_module_name: str,
-        stateful: bool = True,
         instrumenting_library_version: str = "",
     ) -> "Meter":
         # pylint:disable=no-self-use,unused-argument
@@ -376,15 +368,19 @@ def unregister_observer(self, observer: "Observer") -> None:
 
 def get_meter(
     instrumenting_module_name: str,
-    stateful: bool = True,
     instrumenting_library_version: str = "",
+    meter_provider: Optional[MeterProvider] = None,
 ) -> "Meter":
     """Returns a `Meter` for use by the given instrumentation library.
     This function is a convenience wrapper for
     opentelemetry.metrics.get_meter_provider().get_meter
+
+    If meter_provider is omitted the current configured one is used.
     """
-    return get_meter_provider().get_meter(
-        instrumenting_module_name, stateful, instrumenting_library_version
+    if meter_provider is None:
+        meter_provider = get_meter_provider()
+    return meter_provider.get_meter(
+        instrumenting_module_name, instrumenting_library_version
     )
 
 
diff --git a/opentelemetry-sdk/CHANGELOG.md b/opentelemetry-sdk/CHANGELOG.md
@@ -2,6 +2,8 @@
 
 ## Unreleased
 
+- Move stateful & resource from Meter to MeterProvider
+  ([#751](https://github.com/open-telemetry/opentelemetry-python/pull/751))
 - Rename Measure to ValueRecorder in metrics
   ([#761](https://github.com/open-telemetry/opentelemetry-python/pull/761))
 
diff --git a/opentelemetry-sdk/src/opentelemetry/sdk/metrics/__init__.py b/opentelemetry-sdk/src/opentelemetry/sdk/metrics/__init__.py
@@ -270,22 +270,21 @@ class Meter(metrics_api.Meter):
     """See `opentelemetry.metrics.Meter`.
 
     Args:
+        source: The `MeterProvider` that created this meter.
         instrumentation_info: The `InstrumentationInfo` for this meter.
-        stateful: Indicates whether the meter is stateful.
     """
 
     def __init__(
         self,
+        source: "MeterProvider",
         instrumentation_info: "InstrumentationInfo",
-        stateful: bool,
-        resource: Resource = Resource.create_empty(),
     ):
         self.instrumentation_info = instrumentation_info
+        self.batcher = UngroupedBatcher(source.stateful)
+        self.resource = source.resource
         self.metrics = set()
         self.observers = set()
-        self.batcher = UngroupedBatcher(stateful)
         self.observers_lock = threading.Lock()
-        self.resource = resource
 
     def collect(self) -> None:
         """Collects all the metrics created with this `Meter` for export.
@@ -398,21 +397,29 @@ def unregister_observer(self, observer: "Observer") -> None:
 
 
 class MeterProvider(metrics_api.MeterProvider):
-    def __init__(self, resource: Resource = Resource.create_empty()):
+    """See `opentelemetry.metrics.MeterProvider`.
+
+    Args:
+        stateful: Indicates whether meters created are going to be stateful
+        resource: Resource for this MeterProvider
+    """
+
+    def __init__(
+        self, stateful=True, resource: Resource = Resource.create_empty(),
+    ):
+        self.stateful = stateful
         self.resource = resource
 
     def get_meter(
         self,
         instrumenting_module_name: str,
-        stateful=True,
         instrumenting_library_version: str = "",
     ) -> "metrics_api.Meter":
         if not instrumenting_module_name:  # Reject empty strings too.
             raise ValueError("get_meter called with missing module name.")
         return Meter(
+            self,
             InstrumentationInfo(
                 instrumenting_module_name, instrumenting_library_version
             ),
-            stateful=stateful,
-            resource=self.resource,
         )
diff --git a/opentelemetry-sdk/tests/metrics/test_metrics.py b/opentelemetry-sdk/tests/metrics/test_metrics.py
@@ -21,6 +21,11 @@
 
 
 class TestMeterProvider(unittest.TestCase):
+    def test_stateful(self):
+        meter_provider = metrics.MeterProvider(stateful=False)
+        meter = meter_provider.get_meter(__name__)
+        self.assertIs(meter.batcher.stateful, False)
+
     def test_resource(self):
         resource = resources.Resource.create({})
         meter_provider = metrics.MeterProvider(resource=resource)
