api/sdk: Observer to ValueObserver (open-telemetry#764)

Author: lzchen

docs/examples/basic_meter/observer.py

@@ -19,7 +19,7 @@
 import psutil
 
 from opentelemetry import metrics
-from opentelemetry.sdk.metrics import MeterProvider
+from opentelemetry.sdk.metrics import MeterProvider, ValueObserver
 from opentelemetry.sdk.metrics.export import ConsoleMetricsExporter
 from opentelemetry.sdk.metrics.export.batcher import UngroupedBatcher
 from opentelemetry.sdk.metrics.export.controller import PushController
@@ -43,6 +43,7 @@ def get_cpu_usage_callback(observer):
     description="per-cpu usage",
     unit="1",
     value_type=float,
+    observer_type=ValueObserver,
     label_keys=("cpu_number",),
 )
 

ext/opentelemetry-ext-opencensusexporter/src/opentelemetry/ext/opencensusexporter/metrics_exporter/__init__.py

@@ -114,10 +114,10 @@ def translate_to_collector(
             )
 
         metric_descriptor = metrics_pb2.MetricDescriptor(
-            name=metric_record.metric.name,
-            description=metric_record.metric.description,
-            unit=metric_record.metric.unit,
-            type=get_collector_metric_type(metric_record.metric),
+            name=metric_record.instrument.name,
+            description=metric_record.instrument.description,
+            unit=metric_record.instrument.unit,
+            type=get_collector_metric_type(metric_record.instrument),
             label_keys=label_keys,
         )
 
@@ -151,14 +151,14 @@ def get_collector_point(metric_record: MetricRecord) -> metrics_pb2.Point:
             metric_record.aggregator.last_update_timestamp
         )
     )
-    if metric_record.metric.value_type == int:
+    if metric_record.instrument.value_type == int:
         point.int64_value = metric_record.aggregator.checkpoint
-    elif metric_record.metric.value_type == float:
+    elif metric_record.instrument.value_type == float:
         point.double_value = metric_record.aggregator.checkpoint
     else:
         raise TypeError(
             "Unsupported metric type: {}".format(
-                metric_record.metric.value_type
+                metric_record.instrument.value_type
             )
         )
     return point

ext/opentelemetry-ext-opencensusexporter/tests/test_otcollector_metrics_exporter.py

@@ -92,21 +92,21 @@ def test_get_collector_point(self):
             "testName", "testDescription", "unit", float, ValueRecorder
         )
         result = metrics_exporter.get_collector_point(
-            MetricRecord(aggregator, self._key_labels, int_counter)
+            MetricRecord(int_counter, self._key_labels, aggregator)
         )
         self.assertIsInstance(result, metrics_pb2.Point)
         self.assertIsInstance(result.timestamp, Timestamp)
         self.assertEqual(result.int64_value, 0)
         aggregator.update(123.5)
         aggregator.take_checkpoint()
         result = metrics_exporter.get_collector_point(
-            MetricRecord(aggregator, self._key_labels, float_counter)
+            MetricRecord(float_counter, self._key_labels, aggregator)
         )
         self.assertEqual(result.double_value, 123.5)
         self.assertRaises(
             TypeError,
             metrics_exporter.get_collector_point(
-                MetricRecord(aggregator, self._key_labels, valuerecorder)
+                MetricRecord(valuerecorder, self._key_labels, aggregator)
             ),
         )
 
@@ -122,7 +122,7 @@ def test_export(self):
             "testname", "testdesc", "unit", int, Counter, ["environment"]
         )
         record = MetricRecord(
-            aggregate.CounterAggregator(), self._key_labels, test_metric
+            test_metric, self._key_labels, aggregate.CounterAggregator(),
         )
 
         result = collector_exporter.export([record])
@@ -147,7 +147,7 @@ def test_translate_to_collector(self):
         aggregator = aggregate.CounterAggregator()
         aggregator.update(123)
         aggregator.take_checkpoint()
-        record = MetricRecord(aggregator, self._key_labels, test_metric)
+        record = MetricRecord(test_metric, self._key_labels, aggregator,)
         output_metrics = metrics_exporter.translate_to_collector([record])
         self.assertEqual(len(output_metrics), 1)
         self.assertIsInstance(output_metrics[0], metrics_pb2.Metric)

ext/opentelemetry-ext-prometheus/src/opentelemetry/ext/prometheus/__init__.py

@@ -152,22 +152,22 @@ def _translate_to_prometheus(self, metric_record: MetricRecord):
         metric_name = ""
         if self._prefix != "":
             metric_name = self._prefix + "_"
-        metric_name += self._sanitize(metric_record.metric.name)
+        metric_name += self._sanitize(metric_record.instrument.name)
 
-        if isinstance(metric_record.metric, Counter):
+        if isinstance(metric_record.instrument, Counter):
             prometheus_metric = CounterMetricFamily(
                 name=metric_name,
-                documentation=metric_record.metric.description,
+                documentation=metric_record.instrument.description,
                 labels=label_keys,
             )
             prometheus_metric.add_metric(
                 labels=label_values, value=metric_record.aggregator.checkpoint
             )
         # TODO: Add support for histograms when supported in OT
-        elif isinstance(metric_record.metric, ValueRecorder):
+        elif isinstance(metric_record.instrument, ValueRecorder):
             prometheus_metric = UnknownMetricFamily(
                 name=metric_name,
-                documentation=metric_record.metric.description,
+                documentation=metric_record.instrument.description,
                 labels=label_keys,
             )
             prometheus_metric.add_metric(
@@ -176,7 +176,7 @@ def _translate_to_prometheus(self, metric_record: MetricRecord):
 
         else:
             logger.warning(
-                "Unsupported metric type. %s", type(metric_record.metric)
+                "Unsupported metric type. %s", type(metric_record.instrument)
             )
         return prometheus_metric
 

ext/opentelemetry-ext-prometheus/tests/test_prometheus_exporter.py

@@ -67,7 +67,7 @@ def test_shutdown(self):
     def test_export(self):
         with self._registry_register_patch:
             record = MetricRecord(
-                CounterAggregator(), self._labels_key, self._test_metric
+                self._test_metric, self._labels_key, CounterAggregator(),
             )
             exporter = PrometheusMetricsExporter()
             result = exporter.export([record])
@@ -90,7 +90,7 @@ def test_counter_to_prometheus(self):
         aggregator = CounterAggregator()
         aggregator.update(123)
         aggregator.take_checkpoint()
-        record = MetricRecord(aggregator, key_labels, metric)
+        record = MetricRecord(metric, key_labels, aggregator)
         collector = CustomCollector("testprefix")
         collector.add_metrics_data([record])
 
@@ -118,7 +118,7 @@ def test_invalid_metric(self):
         )
         labels = {"environment": "staging"}
         key_labels = metrics.get_labels_as_key(labels)
-        record = MetricRecord(None, key_labels, metric)
+        record = MetricRecord(metric, key_labels, None)
         collector = CustomCollector("testprefix")
         collector.add_metrics_data([record])
         collector.collect()

ext/opentelemetry-ext-system-metrics/src/opentelemetry/ext/system_metrics/__init__.py

@@ -58,6 +58,7 @@
 import psutil
 
 from opentelemetry import metrics
+from opentelemetry.sdk.metrics import ValueObserver
 from opentelemetry.sdk.metrics.export import MetricsExporter
 from opentelemetry.sdk.metrics.export.controller import PushController
 
@@ -106,6 +107,7 @@ def __init__(
             description="System memory",
             unit="bytes",
             value_type=int,
+            observer_type=ValueObserver,
         )
 
         self.meter.register_observer(
@@ -114,6 +116,7 @@ def __init__(
             description="System CPU",
             unit="seconds",
             value_type=float,
+            observer_type=ValueObserver,
         )
 
         self.meter.register_observer(
@@ -122,6 +125,7 @@ def __init__(
             description="System network bytes",
             unit="bytes",
             value_type=int,
+            observer_type=ValueObserver,
         )
 
         self.meter.register_observer(
@@ -130,6 +134,7 @@ def __init__(
             description="Runtime memory",
             unit="bytes",
             value_type=int,
+            observer_type=ValueObserver,
         )
 
         self.meter.register_observer(
@@ -138,6 +143,7 @@ def __init__(
             description="Runtime CPU",
             unit="seconds",
             value_type=float,
+            observer_type=ValueObserver,
         )
 
         self.meter.register_observer(
@@ -146,9 +152,10 @@ def __init__(
             description="Runtime: gc objects",
             unit="objects",
             value_type=int,
+            observer_type=ValueObserver,
         )
 
-    def _get_system_memory(self, observer: metrics.Observer) -> None:
+    def _get_system_memory(self, observer: metrics.ValueObserver) -> None:
         """Observer callback for memory available
 
         Args:
@@ -161,7 +168,7 @@ def _get_system_memory(self, observer: metrics.Observer) -> None:
                 getattr(system_memory, metric), self._system_memory_labels
             )
 
-    def _get_system_cpu(self, observer: metrics.Observer) -> None:
+    def _get_system_cpu(self, observer: metrics.ValueObserver) -> None:
         """Observer callback for system cpu
 
         Args:
@@ -174,7 +181,7 @@ def _get_system_cpu(self, observer: metrics.Observer) -> None:
                 getattr(cpu_times, _type), self._system_cpu_labels
             )
 
-    def _get_network_bytes(self, observer: metrics.Observer) -> None:
+    def _get_network_bytes(self, observer: metrics.ValueObserver) -> None:
         """Observer callback for network bytes
 
         Args:
@@ -187,7 +194,7 @@ def _get_network_bytes(self, observer: metrics.Observer) -> None:
                 getattr(net_io, _type), self._network_bytes_labels
             )
 
-    def _get_runtime_memory(self, observer: metrics.Observer) -> None:
+    def _get_runtime_memory(self, observer: metrics.ValueObserver) -> None:
         """Observer callback for runtime memory
 
         Args:
@@ -200,7 +207,7 @@ def _get_runtime_memory(self, observer: metrics.Observer) -> None:
                 getattr(proc_memory, _type), self._runtime_memory_labels
             )
 
-    def _get_runtime_cpu(self, observer: metrics.Observer) -> None:
+    def _get_runtime_cpu(self, observer: metrics.ValueObserver) -> None:
         """Observer callback for runtime CPU
 
         Args:
@@ -213,7 +220,7 @@ def _get_runtime_cpu(self, observer: metrics.Observer) -> None:
                 getattr(proc_cpu, _type), self._runtime_cpu_labels
             )
 
-    def _get_runtime_gc_count(self, observer: metrics.Observer) -> None:
+    def _get_runtime_gc_count(self, observer: metrics.ValueObserver) -> None:
         """Observer callback for garbage collection
 
         Args:

ext/opentelemetry-ext-system-metrics/tests/test_system_metrics.py

@@ -54,7 +54,7 @@ def _assert_metrics(self, observer_name, system_metrics, expected):
         ):
             if (
                 metric.labels in expected
-                and metric.metric.name == observer_name
+                and metric.instrument.name == observer_name
             ):
                 self.assertEqual(
                     metric.aggregator.checkpoint.last, expected[metric.labels],

opentelemetry-api/CHANGELOG.md

@@ -6,6 +6,8 @@
   ([#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))
+- Rename Observer to ValueObserver
+  ([#764](https://github.com/open-telemetry/opentelemetry-python/pull/764))
 
 ## 0.8b0
 

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

@@ -162,7 +162,6 @@ class Observer(abc.ABC):
     """An observer type metric instrument used to capture a current set of
     values.
 
-
     Observer instruments are asynchronous, a callback is invoked with the
     observer instrument as argument allowing the user to capture multiple
     values per collection interval.
@@ -190,6 +189,18 @@ def observe(self, value: ValueT, labels: Dict[str, str]) -> None:
         """
 
 
+class ValueObserver(Observer):
+    """No-op implementation of ``ValueObserver``."""
+
+    def observe(self, value: ValueT, labels: Dict[str, str]) -> None:
+        """Captures ``value`` to the valueobserver.
+
+        Args:
+            value: The value to capture to this valueobserver metric.
+            labels: Labels associated to ``value``.
+        """
+
+
 class MeterProvider(abc.ABC):
     @abc.abstractmethod
     def get_meter(
@@ -232,7 +243,9 @@ def get_meter(
         return DefaultMeter()
 
 
-MetricT = TypeVar("MetricT", Counter, ValueRecorder, Observer)
+MetricT = TypeVar("MetricT", Counter, ValueRecorder)
+InstrumentT = TypeVar("InstrumentT", Counter, Observer, ValueRecorder)
+ObserverT = TypeVar("ObserverT", bound=Observer)
 ObserverCallbackT = Callable[[Observer], None]
 
 
@@ -297,6 +310,7 @@ def register_observer(
         description: str,
         unit: str,
         value_type: Type[ValueT],
+        observer_type: Type[ObserverT],
         label_keys: Sequence[str] = (),
         enabled: bool = True,
     ) -> "Observer":
@@ -310,6 +324,7 @@ def register_observer(
             unit: Unit of the metric values following the UCUM convention
                 (https://unitsofmeasure.org/ucum.html).
             value_type: The type of values being recorded by the metric.
+            observer_type: The type of observer being registered.
             label_keys: The keys for the labels with dynamic values.
             enabled: Whether to report the metric by default.
         Returns: A new ``Observer`` metric instrument.
@@ -354,6 +369,7 @@ def register_observer(
         description: str,
         unit: str,
         value_type: Type[ValueT],
+        observer_type: Type[ObserverT],
         label_keys: Sequence[str] = (),
         enabled: bool = True,
     ) -> "Observer":

opentelemetry-api/tests/test_implementation.py

@@ -83,7 +83,9 @@ def test_create_metric(self):
     def test_register_observer(self):
         meter = metrics.DefaultMeter()
         callback = mock.Mock()
-        observer = meter.register_observer(callback, "", "", "", int, (), True)
+        observer = meter.register_observer(
+            callback, "", "", "", int, metrics.ValueObserver
+        )
         self.assertIsInstance(observer, metrics.DefaultObserver)
 
     def test_unregister_observer(self):