From 3629f5aa5d1961d8efd70413cda7941b1105662c Mon Sep 17 00:00:00 2001
From: Leighton <lechen@microsoft.com>
Date: Thu, 31 Oct 2019 16:13:37 -0700
Subject: [PATCH 01/15] Implement labelset

---
 .../metrics_example.py                        |  8 +--
 .../src/opentelemetry/metrics/__init__.py     | 65 ++++++++++++++-----
 .../src/opentelemetry/sdk/metrics/__init__.py | 63 ++++++++++++++----
 3 files changed, 102 insertions(+), 34 deletions(-)

diff --git a/examples/opentelemetry-example-app/src/opentelemetry_example_app/metrics_example.py b/examples/opentelemetry-example-app/src/opentelemetry_example_app/metrics_example.py
index 41bdba85972..7e9a204891a 100644
--- a/examples/opentelemetry-example-app/src/opentelemetry_example_app/metrics_example.py
+++ b/examples/opentelemetry-example-app/src/opentelemetry_example_app/metrics_example.py
@@ -30,17 +30,17 @@
     ("environment",),
 )
 
-label_values = ("staging",)
+label_set = meter.get_label_set({"environment":"staging"})
 
 # Direct metric usage
-counter.add(label_values, 25)
+counter.add(label_set, 25)
 
 # Handle usage
-counter_handle = counter.get_handle(label_values)
+counter_handle = counter.get_handle(label_set)
 counter_handle.add(100)
 
 # Record batch usage
-meter.record_batch(label_values, [(counter, 50)])
+meter.record_batch(label_set, [(counter, 50)])
 print(counter_handle.data)
 
 # TODO: exporters
diff --git a/opentelemetry-api/src/opentelemetry/metrics/__init__.py b/opentelemetry-api/src/opentelemetry/metrics/__init__.py
index e866aa97cfa..2987e5695cb 100644
--- a/opentelemetry-api/src/opentelemetry/metrics/__init__.py
+++ b/opentelemetry-api/src/opentelemetry/metrics/__init__.py
@@ -26,7 +26,7 @@
 
 
 """
-from typing import Callable, Optional, Sequence, Tuple, Type, TypeVar
+from typing import Callable, Dict, Optional, Sequence, Tuple, Type, TypeVar
 
 from opentelemetry.util import loader
 
@@ -66,6 +66,24 @@ def record(self, value: ValueT) -> None:
             value: The value to record to the handle.
         """
 
+class LabelSet:
+    """A canonicalized set of labels useful for preaggregation
+
+    Re-usable LabelSet objects provide a potential optimization for scenarios
+    where handles might not be effective. For example, if the LabelSet will be
+    re-used but only used once per metrics, handles do not offer any
+    optimization. It may best to pre-compute a canonicalized LabelSet once and
+    re-use it with the direct calling convention. LabelSets are immutable and
+    should be opaque in implementation.
+    """
+
+
+class DefaultLabelSet(LabelSet):
+    """The default LabelSet.
+
+    Used when no LabelSet implementation is available.
+    """
+
 
 class Metric:
     """Base class for various types of metrics.
@@ -74,7 +92,7 @@ class Metric:
     handle that the metric holds.
     """
 
-    def get_handle(self, label_values: Sequence[str]) -> "object":
+    def get_handle(self, label_set: LabelSet) -> "object":
         """Gets a handle, used for repeated-use of metrics instruments.
 
         Handles are useful to reduce the cost of repeatedly recording a metric
@@ -85,18 +103,18 @@ def get_handle(self, label_values: Sequence[str]) -> "object":
         a value was not provided are permitted.
 
         Args:
-            label_values: Values to associate with the returned handle.
+            label_set: `LabelSet` to associate with the returned handle.
         """
 
 
 class DefaultMetric(Metric):
     """The default Metric used when no Metric implementation is available."""
 
-    def get_handle(self, label_values: Sequence[str]) -> "DefaultMetricHandle":
+    def get_handle(self, label_set: LabelSet) -> "DefaultMetricHandle":
         """Gets a `DefaultMetricHandle`.
 
         Args:
-            label_values: The label values associated with the handle.
+            label_set: `LabelSet` to associate with the returned handle.
         """
         return DefaultMetricHandle()
 
@@ -104,15 +122,15 @@ def get_handle(self, label_values: Sequence[str]) -> "DefaultMetricHandle":
 class Counter(Metric):
     """A counter type metric that expresses the computation of a sum."""
 
-    def get_handle(self, label_values: Sequence[str]) -> "CounterHandle":
+    def get_handle(self, label_set: LabelSet) -> "CounterHandle":
         """Gets a `CounterHandle`."""
         return CounterHandle()
 
-    def add(self, label_values: Sequence[str], value: ValueT) -> None:
+    def add(self, label_set: LabelSet, value: ValueT) -> None:
         """Increases the value of the counter by ``value``.
 
         Args:
-            label_values: The label values associated with the metric.
+            label_set: `LabelSet` to associate with the returned handle.
             value: The value to add to the counter metric.
         """
 
@@ -126,15 +144,15 @@ class Gauge(Metric):
     the measurement interval is arbitrary.
     """
 
-    def get_handle(self, label_values: Sequence[str]) -> "GaugeHandle":
+    def get_handle(self, label_set: LabelSet) -> "GaugeHandle":
         """Gets a `GaugeHandle`."""
         return GaugeHandle()
 
-    def set(self, label_values: Sequence[str], value: ValueT) -> None:
+    def set(self, label_set: LabelSet, value: ValueT) -> None:
         """Sets the value of the gauge to ``value``.
 
         Args:
-            label_values: The label values associated with the metric.
+            label_set: `LabelSet` to associate with the returned handle.
             value: The value to set the gauge metric to.
         """
 
@@ -147,15 +165,15 @@ class Measure(Metric):
     Negative inputs will be discarded when monotonic is True.
     """
 
-    def get_handle(self, label_values: Sequence[str]) -> "MeasureHandle":
+    def get_handle(self, label_set: LabelSet) -> "MeasureHandle":
         """Gets a `MeasureHandle` with a float value."""
         return MeasureHandle()
 
-    def record(self, label_values: Sequence[str], value: ValueT) -> None:
+    def record(self, label_set: LabelSet, value: ValueT) -> None:
         """Records the ``value`` to the measure.
 
         Args:
-            label_values: The label values associated with the metric.
+            label_set: `LabelSet` to associate with the returned handle.
             value: The value to record to this measure metric.
         """
 
@@ -174,7 +192,7 @@ class Meter:
 
     def record_batch(
         self,
-        label_values: Sequence[str],
+        label_set: LabelSet,
         record_tuples: Sequence[Tuple["Metric", ValueT]],
     ) -> None:
         """Atomically records a batch of `Metric` and value pairs.
@@ -184,7 +202,7 @@ def record_batch(
         match the key-value pairs in the label tuples.
 
         Args:
-            label_values: The label values associated with all measurements in
+            label_set: The `LabelSet` associated with all measurements in
                 the batch. A measurement is a tuple, representing the `Metric`
                 being recorded and the corresponding value to record.
             record_tuples: A sequence of pairs of `Metric` s and the
@@ -211,8 +229,6 @@ def create_metric(
             value_type: The type of values being recorded by the metric.
             metric_type: The type of metric being created.
             label_keys: The keys for the labels with dynamic values.
-                Order of the sequence is important as the same order must be
-                used on recording when suppling values for these labels.
             enabled: Whether to report the metric by default.
             monotonic: Whether to only allow non-negative values.
 
@@ -221,6 +237,19 @@ def create_metric(
         # pylint: disable=no-self-use
         return DefaultMetric()
 
+    def get_label_set(self,
+                      labels: Dict[str, str],
+                      encoded: str) -> "LabelSet":
+        """Gets a `LabelSet` with the given `labels`.
+
+        Args:
+            labels: A dictionary representing label key to label value pairs.
+            encoded: A unique encoding to represent this `LabelSet`.
+
+        Returns: A `LabelSet` object canonicalized using the given input.
+        """
+        # pylint: disable=no-self-use
+        return DefaultLabelSet()
 
 # Once https://github.com/python/mypy/issues/7092 is resolved,
 # the following type definition should be replaced with
diff --git a/opentelemetry-sdk/src/opentelemetry/sdk/metrics/__init__.py b/opentelemetry-sdk/src/opentelemetry/sdk/metrics/__init__.py
index 0a941cd0d18..0022c60c52c 100644
--- a/opentelemetry-sdk/src/opentelemetry/sdk/metrics/__init__.py
+++ b/opentelemetry-sdk/src/opentelemetry/sdk/metrics/__init__.py
@@ -13,13 +13,26 @@
 # limitations under the License.
 
 import logging
-from typing import Sequence, Tuple, Type
+from collections import OrderedDict
+from typing import Dict, Sequence, Tuple, Type
 
 from opentelemetry import metrics as metrics_api
 
 logger = logging.getLogger(__name__)
 
 
+class LabelSet(metrics_api.LabelSet):
+    """See `opentelemetry.metrics.LabelSet."""
+
+    def __init__(
+        self,
+        labels: Dict[str, str] = None,
+        encoded: str = ""
+    ):
+        self.labels = labels
+        self.encoded = encoded
+
+
 class BaseHandle:
     def __init__(
         self,
@@ -97,14 +110,14 @@ def __init__(
         self.monotonic = monotonic
         self.handles = {}
 
-    def get_handle(self, label_values: Sequence[str]) -> BaseHandle:
+    def get_handle(self, label_set: LabelSet) -> BaseHandle:
         """See `opentelemetry.metrics.Metric.get_handle`."""
-        handle = self.handles.get(label_values)
+        handle = self.handles.get(label_set.encoded)
         if not handle:
             handle = self.HANDLE_TYPE(
                 self.value_type, self.enabled, self.monotonic
             )
-        self.handles[label_values] = handle
+        self.handles[label_set.encoded] = handle
         return handle
 
     UPDATE_FUNCTION = lambda x, y: None  # noqa: E731
@@ -141,10 +154,10 @@ def __init__(
         )
 
     def add(
-        self, label_values: Sequence[str], value: metrics_api.ValueT
+        self, label_set: LabelSet, value: metrics_api.ValueT
     ) -> None:
         """See `opentelemetry.metrics.Counter.add`."""
-        self.get_handle(label_values).add(value)
+        self.get_handle(label_set).add(value)
 
     UPDATE_FUNCTION = add
 
@@ -179,10 +192,10 @@ def __init__(
         )
 
     def set(
-        self, label_values: Sequence[str], value: metrics_api.ValueT
+        self, label_set: LabelSet, value: metrics_api.ValueT
     ) -> None:
         """See `opentelemetry.metrics.Gauge.set`."""
-        self.get_handle(label_values).set(value)
+        self.get_handle(label_set).set(value)
 
     UPDATE_FUNCTION = set
 
@@ -217,25 +230,30 @@ def __init__(
         )
 
     def record(
-        self, label_values: Sequence[str], value: metrics_api.ValueT
+        self, label_set: LabelSet, value: metrics_api.ValueT
     ) -> None:
         """See `opentelemetry.metrics.Measure.record`."""
-        self.get_handle(label_values).record(value)
+        self.get_handle(label_set).record(value)
 
     UPDATE_FUNCTION = record
 
+# Singleton of meter.get_label_set() with zero arguments
+EMPTY_LABEL_SET = LabelSet()
 
 class Meter(metrics_api.Meter):
     """See `opentelemetry.metrics.Meter`."""
 
+    def __init__(self):
+        self.labels = {}
+
     def record_batch(
         self,
-        label_values: Sequence[str],
+        label_set: LabelSet,
         record_tuples: Sequence[Tuple[metrics_api.Metric, metrics_api.ValueT]],
     ) -> None:
         """See `opentelemetry.metrics.Meter.record_batch`."""
         for metric, value in record_tuples:
-            metric.UPDATE_FUNCTION(label_values, value)
+            metric.UPDATE_FUNCTION(label_set, value)
 
     def create_metric(
         self,
@@ -260,5 +278,26 @@ def create_metric(
             monotonic=monotonic,
         )
 
+    def get_label_set(self, labels: Dict[str, str]):
+        """See `opentelemetry.metrics.Meter.create_metric`.
+        
+        This implementation encodes the labels to use as a map key.
+
+        Args:
+            labels: The dictionary of label keys to label values.
+        """
+        if not len(labels):
+            return EMPTY_LABEL_SET
+        sorted_labels = OrderedDict(sorted(labels.items()))
+        # Uses statsd encoding for labels
+        encoded = '|#' + ','.join('%s:%s' % (key,value) \
+            for (key, value) in sorted_labels.items())
+        # If LabelSet exists for this meter in memory, use existing one
+        if not self.labels.get(encoded):
+            self.labels[encoded] = \
+                LabelSet(labels=sorted_labels, encoded=encoded)
+        return self.labels[encoded]
+
 
 meter = Meter()
+

From 6a433fed472855cbd0807059a635f956b106e369 Mon Sep 17 00:00:00 2001
From: Leighton <lechen@microsoft.com>
Date: Fri, 1 Nov 2019 12:03:49 -0700
Subject: [PATCH 02/15] add tests

---
 .../src/opentelemetry/metrics/__init__.py     |  5 +-
 .../tests/metrics/test_metrics.py             |  4 +
 .../tests/metrics/test_metrics.py             | 82 +++++++++++++------
 3 files changed, 64 insertions(+), 27 deletions(-)

diff --git a/opentelemetry-api/src/opentelemetry/metrics/__init__.py b/opentelemetry-api/src/opentelemetry/metrics/__init__.py
index 2987e5695cb..d6e1be88f38 100644
--- a/opentelemetry-api/src/opentelemetry/metrics/__init__.py
+++ b/opentelemetry-api/src/opentelemetry/metrics/__init__.py
@@ -238,13 +238,12 @@ def create_metric(
         return DefaultMetric()
 
     def get_label_set(self,
-                      labels: Dict[str, str],
-                      encoded: str) -> "LabelSet":
+                      labels: Dict[str, str]
+                      ) -> "LabelSet":
         """Gets a `LabelSet` with the given `labels`.
 
         Args:
             labels: A dictionary representing label key to label value pairs.
-            encoded: A unique encoding to represent this `LabelSet`.
 
         Returns: A `LabelSet` object canonicalized using the given input.
         """
diff --git a/opentelemetry-api/tests/metrics/test_metrics.py b/opentelemetry-api/tests/metrics/test_metrics.py
index 758534f2356..177f444fbc1 100644
--- a/opentelemetry-api/tests/metrics/test_metrics.py
+++ b/opentelemetry-api/tests/metrics/test_metrics.py
@@ -29,6 +29,10 @@ def test_record_batch(self):
     def test_create_metric(self):
         metric = self.meter.create_metric("", "", "", float, metrics.Counter)
         self.assertIsInstance(metric, metrics.DefaultMetric)
+    
+    def test_get_label_set(self):
+        metric = self.meter.get_label_set({})
+        self.assertIsInstance(metric, metrics.DefaultLabelSet)
 
 
 class TestMetrics(unittest.TestCase):
diff --git a/opentelemetry-sdk/tests/metrics/test_metrics.py b/opentelemetry-sdk/tests/metrics/test_metrics.py
index cc37bc1a8aa..c9284794283 100644
--- a/opentelemetry-sdk/tests/metrics/test_metrics.py
+++ b/opentelemetry-sdk/tests/metrics/test_metrics.py
@@ -27,35 +27,38 @@ def test_extends_api(self):
     def test_record_batch(self):
         meter = metrics.Meter()
         label_keys = ("key1",)
-        label_values = ("value1",)
         counter = metrics.Counter("name", "desc", "unit", float, label_keys)
+        kvp = {"key1":"value1"}
+        label_set = meter.get_label_set(kvp)
         record_tuples = [(counter, 1.0)]
-        meter.record_batch(label_values, record_tuples)
-        self.assertEqual(counter.get_handle(label_values).data, 1.0)
+        meter.record_batch(label_set, record_tuples)
+        self.assertEqual(counter.get_handle(label_set).data, 1.0)
 
     def test_record_batch_multiple(self):
         meter = metrics.Meter()
         label_keys = ("key1", "key2", "key3")
-        label_values = ("value1", "value2", "value3")
+        kvp = {"key1":"value1", "key2":"value2", "key3":"value3"}
+        label_set = meter.get_label_set(kvp)
         counter = metrics.Counter("name", "desc", "unit", float, label_keys)
         gauge = metrics.Gauge("name", "desc", "unit", int, label_keys)
         measure = metrics.Measure("name", "desc", "unit", float, label_keys)
         record_tuples = [(counter, 1.0), (gauge, 5), (measure, 3.0)]
-        meter.record_batch(label_values, record_tuples)
-        self.assertEqual(counter.get_handle(label_values).data, 1.0)
-        self.assertEqual(gauge.get_handle(label_values).data, 5)
-        self.assertEqual(measure.get_handle(label_values).data, 0)
+        meter.record_batch(label_set, record_tuples)
+        self.assertEqual(counter.get_handle(label_set).data, 1.0)
+        self.assertEqual(gauge.get_handle(label_set).data, 5)
+        self.assertEqual(measure.get_handle(label_set).data, 0)
 
     def test_record_batch_exists(self):
         meter = metrics.Meter()
         label_keys = ("key1",)
-        label_values = ("value1",)
+        kvp = {"key1":"value1"}
+        label_set = meter.get_label_set(kvp)
         counter = metrics.Counter("name", "desc", "unit", float, label_keys)
-        counter.add(label_values, 1.0)
-        handle = counter.get_handle(label_values)
+        counter.add(label_set, 1.0)
+        handle = counter.get_handle(label_set)
         record_tuples = [(counter, 1.0)]
-        meter.record_batch(label_values, record_tuples)
-        self.assertEqual(counter.get_handle(label_values), handle)
+        meter.record_batch(label_set, record_tuples)
+        self.assertEqual(counter.get_handle(label_set), handle)
         self.assertEqual(handle.data, 2.0)
 
     def test_create_metric(self):
@@ -85,41 +88,72 @@ def test_create_measure(self):
         self.assertEqual(measure.value_type, float)
         self.assertEqual(measure.name, "name")
 
+    def test_get_label_set(self):
+        meter = metrics.Meter()
+        kvp = {"environment":"staging", "a":"z"}
+        label_set = meter.get_label_set(kvp)
+        encoding = '|#a:z,environment:staging'
+        self.assertEqual(label_set.encoded, encoding)
+
+    def test_get_label_set_empty(self):
+        meter = metrics.Meter()
+        kvp = {}
+        label_set = meter.get_label_set(kvp)
+        self.assertEqual(label_set, metrics.EMPTY_LABEL_SET)
+
+    def test_get_label_set_exists(self):
+        meter = metrics.Meter()
+        kvp = {"environment":"staging", "a":"z"}
+        label_set = meter.get_label_set(kvp)
+        label_set2 = meter.get_label_set(kvp)
+        self.assertEqual(label_set, label_set2)
+
 
 class TestMetric(unittest.TestCase):
     def test_get_handle(self):
+        meter = metrics.Meter()
         metric_types = [metrics.Counter, metrics.Gauge, metrics.Measure]
         for _type in metric_types:
             metric = _type("name", "desc", "unit", int, ("key",))
-            label_values = ("value",)
-            handle = metric.get_handle(label_values)
-            self.assertEqual(metric.handles.get(label_values), handle)
+            kvp = {"key":"value"}
+            label_set = meter.get_label_set(kvp)
+            handle = metric.get_handle(label_set)
+            self.assertEqual(metric.handles.get(label_set.encoded), handle)
 
 
 class TestCounter(unittest.TestCase):
     def test_add(self):
+        meter = metrics.Meter()
         metric = metrics.Counter("name", "desc", "unit", int, ("key",))
-        handle = metric.get_handle(("value",))
-        metric.add(("value",), 3)
-        metric.add(("value",), 2)
+        kvp = {"key":"value"}
+        label_set = meter.get_label_set(kvp)
+        handle = metric.get_handle(label_set)
+        metric.add(label_set, 3)
+        metric.add(label_set, 2)
         self.assertEqual(handle.data, 5)
 
 
 class TestGauge(unittest.TestCase):
     def test_set(self):
+        meter = metrics.Meter()
         metric = metrics.Gauge("name", "desc", "unit", int, ("key",))
-        handle = metric.get_handle(("value",))
-        metric.set(("value",), 3)
+        kvp = {"key":"value"}
+        label_set = meter.get_label_set(kvp)
+        handle = metric.get_handle(label_set)
+        metric.set(label_set, 3)
         self.assertEqual(handle.data, 3)
-        metric.set(("value",), 2)
+        metric.set(label_set, 2)
         self.assertEqual(handle.data, 2)
 
 
 class TestMeasure(unittest.TestCase):
     def test_record(self):
+        meter = metrics.Meter()
         metric = metrics.Measure("name", "desc", "unit", int, ("key",))
-        handle = metric.get_handle(("value",))
-        metric.record(("value",), 3)
+        kvp = {"key":"value"}
+        label_set = meter.get_label_set(kvp)
+        handle = metric.get_handle(label_set)
+        metric.record(label_set, 3)
         # Record not implemented yet
         self.assertEqual(handle.data, 0)
 

From d816da89968ae8a8267ec0c851e3ba5954c1cdc3 Mon Sep 17 00:00:00 2001
From: Leighton <lechen@microsoft.com>
Date: Fri, 1 Nov 2019 14:22:35 -0700
Subject: [PATCH 03/15] fix lint

---
 .../metrics_example.py                        |  2 +-
 .../src/opentelemetry/metrics/__init__.py     |  6 ++--
 .../tests/metrics/test_metrics.py             | 24 +++++++++-----
 .../src/opentelemetry/sdk/metrics/__init__.py | 31 +++++++------------
 .../tests/metrics/test_metrics.py             | 20 ++++++------
 5 files changed, 42 insertions(+), 41 deletions(-)

diff --git a/examples/opentelemetry-example-app/src/opentelemetry_example_app/metrics_example.py b/examples/opentelemetry-example-app/src/opentelemetry_example_app/metrics_example.py
index 7e9a204891a..246d6c3507d 100644
--- a/examples/opentelemetry-example-app/src/opentelemetry_example_app/metrics_example.py
+++ b/examples/opentelemetry-example-app/src/opentelemetry_example_app/metrics_example.py
@@ -30,7 +30,7 @@
     ("environment",),
 )
 
-label_set = meter.get_label_set({"environment":"staging"})
+label_set = meter.get_label_set({"environment": "staging"})
 
 # Direct metric usage
 counter.add(label_set, 25)
diff --git a/opentelemetry-api/src/opentelemetry/metrics/__init__.py b/opentelemetry-api/src/opentelemetry/metrics/__init__.py
index d6e1be88f38..b275389a538 100644
--- a/opentelemetry-api/src/opentelemetry/metrics/__init__.py
+++ b/opentelemetry-api/src/opentelemetry/metrics/__init__.py
@@ -66,6 +66,7 @@ def record(self, value: ValueT) -> None:
             value: The value to record to the handle.
         """
 
+
 class LabelSet:
     """A canonicalized set of labels useful for preaggregation
 
@@ -237,9 +238,7 @@ def create_metric(
         # pylint: disable=no-self-use
         return DefaultMetric()
 
-    def get_label_set(self,
-                      labels: Dict[str, str]
-                      ) -> "LabelSet":
+    def get_label_set(self, labels: Dict[str, str]) -> "LabelSet":
         """Gets a `LabelSet` with the given `labels`.
 
         Args:
@@ -250,6 +249,7 @@ def get_label_set(self,
         # pylint: disable=no-self-use
         return DefaultLabelSet()
 
+
 # Once https://github.com/python/mypy/issues/7092 is resolved,
 # the following type definition should be replaced with
 # from opentelemetry.util.loader import ImplementationFactory
diff --git a/opentelemetry-api/tests/metrics/test_metrics.py b/opentelemetry-api/tests/metrics/test_metrics.py
index 177f444fbc1..1ae9f177927 100644
--- a/opentelemetry-api/tests/metrics/test_metrics.py
+++ b/opentelemetry-api/tests/metrics/test_metrics.py
@@ -24,12 +24,13 @@ def setUp(self):
 
     def test_record_batch(self):
         counter = metrics.Counter()
-        self.meter.record_batch(("values"), ((counter, 1),))
+        label_set = metrics.LabelSet()
+        self.meter.record_batch(label_set, ((counter, 1),))
 
     def test_create_metric(self):
         metric = self.meter.create_metric("", "", "", float, metrics.Counter)
         self.assertIsInstance(metric, metrics.DefaultMetric)
-    
+
     def test_get_label_set(self):
         metric = self.meter.get_label_set({})
         self.assertIsInstance(metric, metrics.DefaultLabelSet)
@@ -38,35 +39,42 @@ def test_get_label_set(self):
 class TestMetrics(unittest.TestCase):
     def test_default(self):
         default = metrics.DefaultMetric()
-        handle = default.get_handle(("test", "test1"))
+        label_set = metrics.LabelSet()
+        handle = default.get_handle(label_set)
         self.assertIsInstance(handle, metrics.DefaultMetricHandle)
 
     def test_counter(self):
         counter = metrics.Counter()
+        label_set = metrics.LabelSet()
         handle = counter.get_handle(("test", "test1"))
         self.assertIsInstance(handle, metrics.CounterHandle)
 
     def test_counter_add(self):
         counter = metrics.Counter()
-        counter.add(("value",), 1)
+        label_set = metrics.LabelSet()
+        counter.add(label_set, 1)
 
     def test_gauge(self):
         gauge = metrics.Gauge()
-        handle = gauge.get_handle(("test", "test1"))
+        label_set = metrics.LabelSet()
+        handle = gauge.get_handle(label_set)
         self.assertIsInstance(handle, metrics.GaugeHandle)
 
     def test_gauge_set(self):
         gauge = metrics.Gauge()
-        gauge.set(("value",), 1)
+        label_set = metrics.LabelSet()
+        gauge.set(label_set, 1)
 
     def test_measure(self):
         measure = metrics.Measure()
-        handle = measure.get_handle(("test", "test1"))
+        label_set = metrics.LabelSet()
+        handle = measure.get_handle(label_set)
         self.assertIsInstance(handle, metrics.MeasureHandle)
 
     def test_measure_record(self):
         measure = metrics.Measure()
-        measure.record(("value",), 1)
+        label_set = metrics.LabelSet()
+        measure.record(label_set, 1)
 
     def test_default_handle(self):
         metrics.DefaultMetricHandle()
diff --git a/opentelemetry-sdk/src/opentelemetry/sdk/metrics/__init__.py b/opentelemetry-sdk/src/opentelemetry/sdk/metrics/__init__.py
index 0022c60c52c..d008b8c17b5 100644
--- a/opentelemetry-sdk/src/opentelemetry/sdk/metrics/__init__.py
+++ b/opentelemetry-sdk/src/opentelemetry/sdk/metrics/__init__.py
@@ -24,11 +24,7 @@
 class LabelSet(metrics_api.LabelSet):
     """See `opentelemetry.metrics.LabelSet."""
 
-    def __init__(
-        self,
-        labels: Dict[str, str] = None,
-        encoded: str = ""
-    ):
+    def __init__(self, labels: Dict[str, str] = None, encoded: str = ""):
         self.labels = labels
         self.encoded = encoded
 
@@ -153,9 +149,7 @@ def __init__(
             monotonic=monotonic,
         )
 
-    def add(
-        self, label_set: LabelSet, value: metrics_api.ValueT
-    ) -> None:
+    def add(self, label_set: LabelSet, value: metrics_api.ValueT) -> None:
         """See `opentelemetry.metrics.Counter.add`."""
         self.get_handle(label_set).add(value)
 
@@ -191,9 +185,7 @@ def __init__(
             monotonic=monotonic,
         )
 
-    def set(
-        self, label_set: LabelSet, value: metrics_api.ValueT
-    ) -> None:
+    def set(self, label_set: LabelSet, value: metrics_api.ValueT) -> None:
         """See `opentelemetry.metrics.Gauge.set`."""
         self.get_handle(label_set).set(value)
 
@@ -229,17 +221,17 @@ def __init__(
             monotonic=monotonic,
         )
 
-    def record(
-        self, label_set: LabelSet, value: metrics_api.ValueT
-    ) -> None:
+    def record(self, label_set: LabelSet, value: metrics_api.ValueT) -> None:
         """See `opentelemetry.metrics.Measure.record`."""
         self.get_handle(label_set).record(value)
 
     UPDATE_FUNCTION = record
 
+
 # Singleton of meter.get_label_set() with zero arguments
 EMPTY_LABEL_SET = LabelSet()
 
+
 class Meter(metrics_api.Meter):
     """See `opentelemetry.metrics.Meter`."""
 
@@ -290,14 +282,15 @@ def get_label_set(self, labels: Dict[str, str]):
             return EMPTY_LABEL_SET
         sorted_labels = OrderedDict(sorted(labels.items()))
         # Uses statsd encoding for labels
-        encoded = '|#' + ','.join('%s:%s' % (key,value) \
-            for (key, value) in sorted_labels.items())
+        encoded = "|#" + ",".join(
+            "%s:%s" % (key, value) for (key, value) in sorted_labels.items()
+        )
         # If LabelSet exists for this meter in memory, use existing one
         if not self.labels.get(encoded):
-            self.labels[encoded] = \
-                LabelSet(labels=sorted_labels, encoded=encoded)
+            self.labels[encoded] = LabelSet(
+                labels=sorted_labels, encoded=encoded
+            )
         return self.labels[encoded]
 
 
 meter = Meter()
-
diff --git a/opentelemetry-sdk/tests/metrics/test_metrics.py b/opentelemetry-sdk/tests/metrics/test_metrics.py
index c9284794283..0427dd2108b 100644
--- a/opentelemetry-sdk/tests/metrics/test_metrics.py
+++ b/opentelemetry-sdk/tests/metrics/test_metrics.py
@@ -28,7 +28,7 @@ def test_record_batch(self):
         meter = metrics.Meter()
         label_keys = ("key1",)
         counter = metrics.Counter("name", "desc", "unit", float, label_keys)
-        kvp = {"key1":"value1"}
+        kvp = {"key1": "value1"}
         label_set = meter.get_label_set(kvp)
         record_tuples = [(counter, 1.0)]
         meter.record_batch(label_set, record_tuples)
@@ -37,7 +37,7 @@ def test_record_batch(self):
     def test_record_batch_multiple(self):
         meter = metrics.Meter()
         label_keys = ("key1", "key2", "key3")
-        kvp = {"key1":"value1", "key2":"value2", "key3":"value3"}
+        kvp = {"key1": "value1", "key2": "value2", "key3": "value3"}
         label_set = meter.get_label_set(kvp)
         counter = metrics.Counter("name", "desc", "unit", float, label_keys)
         gauge = metrics.Gauge("name", "desc", "unit", int, label_keys)
@@ -51,7 +51,7 @@ def test_record_batch_multiple(self):
     def test_record_batch_exists(self):
         meter = metrics.Meter()
         label_keys = ("key1",)
-        kvp = {"key1":"value1"}
+        kvp = {"key1": "value1"}
         label_set = meter.get_label_set(kvp)
         counter = metrics.Counter("name", "desc", "unit", float, label_keys)
         counter.add(label_set, 1.0)
@@ -90,9 +90,9 @@ def test_create_measure(self):
 
     def test_get_label_set(self):
         meter = metrics.Meter()
-        kvp = {"environment":"staging", "a":"z"}
+        kvp = {"environment": "staging", "a": "z"}
         label_set = meter.get_label_set(kvp)
-        encoding = '|#a:z,environment:staging'
+        encoding = "|#a:z,environment:staging"
         self.assertEqual(label_set.encoded, encoding)
 
     def test_get_label_set_empty(self):
@@ -103,7 +103,7 @@ def test_get_label_set_empty(self):
 
     def test_get_label_set_exists(self):
         meter = metrics.Meter()
-        kvp = {"environment":"staging", "a":"z"}
+        kvp = {"environment": "staging", "a": "z"}
         label_set = meter.get_label_set(kvp)
         label_set2 = meter.get_label_set(kvp)
         self.assertEqual(label_set, label_set2)
@@ -115,7 +115,7 @@ def test_get_handle(self):
         metric_types = [metrics.Counter, metrics.Gauge, metrics.Measure]
         for _type in metric_types:
             metric = _type("name", "desc", "unit", int, ("key",))
-            kvp = {"key":"value"}
+            kvp = {"key": "value"}
             label_set = meter.get_label_set(kvp)
             handle = metric.get_handle(label_set)
             self.assertEqual(metric.handles.get(label_set.encoded), handle)
@@ -125,7 +125,7 @@ class TestCounter(unittest.TestCase):
     def test_add(self):
         meter = metrics.Meter()
         metric = metrics.Counter("name", "desc", "unit", int, ("key",))
-        kvp = {"key":"value"}
+        kvp = {"key": "value"}
         label_set = meter.get_label_set(kvp)
         handle = metric.get_handle(label_set)
         metric.add(label_set, 3)
@@ -137,7 +137,7 @@ class TestGauge(unittest.TestCase):
     def test_set(self):
         meter = metrics.Meter()
         metric = metrics.Gauge("name", "desc", "unit", int, ("key",))
-        kvp = {"key":"value"}
+        kvp = {"key": "value"}
         label_set = meter.get_label_set(kvp)
         handle = metric.get_handle(label_set)
         metric.set(label_set, 3)
@@ -150,7 +150,7 @@ class TestMeasure(unittest.TestCase):
     def test_record(self):
         meter = metrics.Meter()
         metric = metrics.Measure("name", "desc", "unit", int, ("key",))
-        kvp = {"key":"value"}
+        kvp = {"key": "value"}
         label_set = meter.get_label_set(kvp)
         handle = metric.get_handle(label_set)
         metric.record(label_set, 3)

From df80425d0afe2cc215cfb463ab321ea26c022cfb Mon Sep 17 00:00:00 2001
From: Leighton <lechen@microsoft.com>
Date: Fri, 1 Nov 2019 14:48:11 -0700
Subject: [PATCH 04/15] fix lint

---
 opentelemetry-api/tests/metrics/test_metrics.py             | 2 +-
 opentelemetry-sdk/src/opentelemetry/sdk/metrics/__init__.py | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/opentelemetry-api/tests/metrics/test_metrics.py b/opentelemetry-api/tests/metrics/test_metrics.py
index 1ae9f177927..77031d614de 100644
--- a/opentelemetry-api/tests/metrics/test_metrics.py
+++ b/opentelemetry-api/tests/metrics/test_metrics.py
@@ -46,7 +46,7 @@ def test_default(self):
     def test_counter(self):
         counter = metrics.Counter()
         label_set = metrics.LabelSet()
-        handle = counter.get_handle(("test", "test1"))
+        handle = counter.get_handle(label_set)
         self.assertIsInstance(handle, metrics.CounterHandle)
 
     def test_counter_add(self):
diff --git a/opentelemetry-sdk/src/opentelemetry/sdk/metrics/__init__.py b/opentelemetry-sdk/src/opentelemetry/sdk/metrics/__init__.py
index d008b8c17b5..49e02781542 100644
--- a/opentelemetry-sdk/src/opentelemetry/sdk/metrics/__init__.py
+++ b/opentelemetry-sdk/src/opentelemetry/sdk/metrics/__init__.py
@@ -272,13 +272,13 @@ def create_metric(
 
     def get_label_set(self, labels: Dict[str, str]):
         """See `opentelemetry.metrics.Meter.create_metric`.
-        
+
         This implementation encodes the labels to use as a map key.
 
         Args:
             labels: The dictionary of label keys to label values.
         """
-        if not len(labels):
+        if len(labels) == 0:
             return EMPTY_LABEL_SET
         sorted_labels = OrderedDict(sorted(labels.items()))
         # Uses statsd encoding for labels

From c9600568440c0c536e0aceb6599cf4b3f60ee2fe Mon Sep 17 00:00:00 2001
From: Leighton <lechen@microsoft.com>
Date: Fri, 1 Nov 2019 15:01:31 -0700
Subject: [PATCH 05/15] fix docs

---
 opentelemetry-api/src/opentelemetry/metrics/__init__.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/opentelemetry-api/src/opentelemetry/metrics/__init__.py b/opentelemetry-api/src/opentelemetry/metrics/__init__.py
index b275389a538..aad70d5ba3d 100644
--- a/opentelemetry-api/src/opentelemetry/metrics/__init__.py
+++ b/opentelemetry-api/src/opentelemetry/metrics/__init__.py
@@ -239,7 +239,7 @@ def create_metric(
         return DefaultMetric()
 
     def get_label_set(self, labels: Dict[str, str]) -> "LabelSet":
-        """Gets a `LabelSet` with the given `labels`.
+        """Gets a `LabelSet` with the given labels.
 
         Args:
             labels: A dictionary representing label key to label value pairs.

From 893640aa787a23131e15cd58089be2d9041b6c5d Mon Sep 17 00:00:00 2001
From: Leighton <lechen@microsoft.com>
Date: Thu, 14 Nov 2019 18:20:54 -0800
Subject: [PATCH 06/15] include meter check

---
 .../src/opentelemetry/sdk/metrics/__init__.py | 39 +++++++++++++++++--
 .../tests/metrics/test_metrics.py             | 37 ++++++++++++------
 2 files changed, 61 insertions(+), 15 deletions(-)

diff --git a/opentelemetry-sdk/src/opentelemetry/sdk/metrics/__init__.py b/opentelemetry-sdk/src/opentelemetry/sdk/metrics/__init__.py
index 49e02781542..7b6c9316635 100644
--- a/opentelemetry-sdk/src/opentelemetry/sdk/metrics/__init__.py
+++ b/opentelemetry-sdk/src/opentelemetry/sdk/metrics/__init__.py
@@ -24,7 +24,11 @@
 class LabelSet(metrics_api.LabelSet):
     """See `opentelemetry.metrics.LabelSet."""
 
-    def __init__(self, labels: Dict[str, str] = None, encoded: str = ""):
+    def __init__(self,
+                 meter: "Meter" = None,
+                 labels: Dict[str, str] = None,
+                 encoded: str = ""):
+        self.meter = meter
         self.labels = labels
         self.encoded = encoded
 
@@ -93,6 +97,7 @@ def __init__(
         description: str,
         unit: str,
         value_type: Type[metrics_api.ValueT],
+        meter: "Meter",
         label_keys: Sequence[str] = None,
         enabled: bool = True,
         monotonic: bool = False,
@@ -101,6 +106,7 @@ def __init__(
         self.description = description
         self.unit = unit
         self.value_type = value_type
+        self.meter = meter
         self.label_keys = label_keys
         self.enabled = enabled
         self.monotonic = monotonic
@@ -108,14 +114,32 @@ def __init__(
 
     def get_handle(self, label_set: LabelSet) -> BaseHandle:
         """See `opentelemetry.metrics.Metric.get_handle`."""
-        handle = self.handles.get(label_set.encoded)
+        lable_set_for = self._label_set_for(label_set)
+        handle = self.handles.get(lable_set_for.encoded)
         if not handle:
             handle = self.HANDLE_TYPE(
                 self.value_type, self.enabled, self.monotonic
             )
-        self.handles[label_set.encoded] = handle
+        self.handles[lable_set_for.encoded] = handle
         return handle
 
+    def _label_set_for(self, label_set: LabelSet) -> LabelSet:
+        """Returns an appropriate `LabelSet` based off this metric's `meter`
+
+        If this metric's `meter` is the same as label_set's meter, that means
+        label_set was created from this metric's `meter` instance and the
+        proper handle can be found. If not, label_set was created using a
+        different `meter` implementation, in which the metric cannot interpret.
+        In this case, return the `EMPTY_LABEL_SET`.
+
+        Args:
+            label_set: The `LabelSet` to check for the same `Meter` implentation.
+        """
+        if label_set.meter and label_set.meter is self.meter:
+            return label_set
+        return EMPTY_LABEL_SET
+
+
     UPDATE_FUNCTION = lambda x, y: None  # noqa: E731
 
 
@@ -135,6 +159,7 @@ def __init__(
         description: str,
         unit: str,
         value_type: Type[metrics_api.ValueT],
+        meter: "Meter",
         label_keys: Sequence[str] = None,
         enabled: bool = True,
         monotonic: bool = True,
@@ -144,6 +169,7 @@ def __init__(
             description,
             unit,
             value_type,
+            meter,
             label_keys=label_keys,
             enabled=enabled,
             monotonic=monotonic,
@@ -171,6 +197,7 @@ def __init__(
         description: str,
         unit: str,
         value_type: Type[metrics_api.ValueT],
+        meter: "Meter",
         label_keys: Sequence[str] = None,
         enabled: bool = True,
         monotonic: bool = False,
@@ -180,6 +207,7 @@ def __init__(
             description,
             unit,
             value_type,
+            meter,
             label_keys=label_keys,
             enabled=enabled,
             monotonic=monotonic,
@@ -207,6 +235,7 @@ def __init__(
         description: str,
         unit: str,
         value_type: Type[metrics_api.ValueT],
+        meter: "Meter",
         label_keys: Sequence[str] = None,
         enabled: bool = False,
         monotonic: bool = False,
@@ -216,6 +245,7 @@ def __init__(
             description,
             unit,
             value_type,
+            meter,
             label_keys=label_keys,
             enabled=enabled,
             monotonic=monotonic,
@@ -265,6 +295,7 @@ def create_metric(
             description,
             unit,
             value_type,
+            self,
             label_keys=label_keys,
             enabled=enabled,
             monotonic=monotonic,
@@ -288,7 +319,7 @@ def get_label_set(self, labels: Dict[str, str]):
         # If LabelSet exists for this meter in memory, use existing one
         if not self.labels.get(encoded):
             self.labels[encoded] = LabelSet(
-                labels=sorted_labels, encoded=encoded
+                self, labels=sorted_labels, encoded=encoded
             )
         return self.labels[encoded]
 
diff --git a/opentelemetry-sdk/tests/metrics/test_metrics.py b/opentelemetry-sdk/tests/metrics/test_metrics.py
index 0427dd2108b..3f060c4e1b4 100644
--- a/opentelemetry-sdk/tests/metrics/test_metrics.py
+++ b/opentelemetry-sdk/tests/metrics/test_metrics.py
@@ -27,7 +27,7 @@ def test_extends_api(self):
     def test_record_batch(self):
         meter = metrics.Meter()
         label_keys = ("key1",)
-        counter = metrics.Counter("name", "desc", "unit", float, label_keys)
+        counter = metrics.Counter("name", "desc", "unit", float, meter,label_keys)
         kvp = {"key1": "value1"}
         label_set = meter.get_label_set(kvp)
         record_tuples = [(counter, 1.0)]
@@ -39,9 +39,9 @@ def test_record_batch_multiple(self):
         label_keys = ("key1", "key2", "key3")
         kvp = {"key1": "value1", "key2": "value2", "key3": "value3"}
         label_set = meter.get_label_set(kvp)
-        counter = metrics.Counter("name", "desc", "unit", float, label_keys)
+        counter = metrics.Counter("name", "desc", "unit", float, meter, label_keys)
         gauge = metrics.Gauge("name", "desc", "unit", int, label_keys)
-        measure = metrics.Measure("name", "desc", "unit", float, label_keys)
+        measure = metrics.Measure("name", "desc", "unit", float, meter, label_keys)
         record_tuples = [(counter, 1.0), (gauge, 5), (measure, 3.0)]
         meter.record_batch(label_set, record_tuples)
         self.assertEqual(counter.get_handle(label_set).data, 1.0)
@@ -53,7 +53,7 @@ def test_record_batch_exists(self):
         label_keys = ("key1",)
         kvp = {"key1": "value1"}
         label_set = meter.get_label_set(kvp)
-        counter = metrics.Counter("name", "desc", "unit", float, label_keys)
+        counter = metrics.Counter("name", "desc", "unit", float, meter, label_keys)
         counter.add(label_set, 1.0)
         handle = counter.get_handle(label_set)
         record_tuples = [(counter, 1.0)]
@@ -64,7 +64,7 @@ def test_record_batch_exists(self):
     def test_create_metric(self):
         meter = metrics.Meter()
         counter = meter.create_metric(
-            "name", "desc", "unit", int, metrics.Counter, ()
+            "name", "desc", "unit", int, metrics.Counter, meter, ()
         )
         self.assertTrue(isinstance(counter, metrics.Counter))
         self.assertEqual(counter.value_type, int)
@@ -73,7 +73,7 @@ def test_create_metric(self):
     def test_create_gauge(self):
         meter = metrics.Meter()
         gauge = meter.create_metric(
-            "name", "desc", "unit", float, metrics.Gauge, ()
+            "name", "desc", "unit", float, metrics.Gauge, meter, ()
         )
         self.assertTrue(isinstance(gauge, metrics.Gauge))
         self.assertEqual(gauge.value_type, float)
@@ -82,7 +82,7 @@ def test_create_gauge(self):
     def test_create_measure(self):
         meter = metrics.Meter()
         measure = meter.create_metric(
-            "name", "desc", "unit", float, metrics.Measure, ()
+            "name", "desc", "unit", float, metrics.Measure, meter, ()
         )
         self.assertTrue(isinstance(measure, metrics.Measure))
         self.assertEqual(measure.value_type, float)
@@ -114,17 +114,32 @@ def test_get_handle(self):
         meter = metrics.Meter()
         metric_types = [metrics.Counter, metrics.Gauge, metrics.Measure]
         for _type in metric_types:
-            metric = _type("name", "desc", "unit", int, ("key",))
+            metric = _type("name", "desc", "unit", int, meter, ("key",))
             kvp = {"key": "value"}
             label_set = meter.get_label_set(kvp)
             handle = metric.get_handle(label_set)
             self.assertEqual(metric.handles.get(label_set.encoded), handle)
 
+    def test_label_set_for(self):
+        meter = metrics.Meter()
+        metric = metrics.Counter("name", "desc", "unit", int, meter, ("key",))
+        kvp = {"environment": "staging", "a": "z"}
+        label_set = meter.get_label_set(kvp)
+        self.assertEqual(metric._label_set_for(label_set), label_set)
+
+    def test_label_set_for_different(self):
+        meter = metrics.Meter()
+        meter2 = metrics.Meter()
+        metric = metrics.Counter("name", "desc", "unit", int, meter, ("key",))
+        kvp = {"environment": "staging", "a": "z"}
+        label_set = meter2.get_label_set(kvp)
+        self.assertEqual(metric._label_set_for(label_set), metrics.EMPTY_LABEL_SET)
+
 
 class TestCounter(unittest.TestCase):
     def test_add(self):
         meter = metrics.Meter()
-        metric = metrics.Counter("name", "desc", "unit", int, ("key",))
+        metric = metrics.Counter("name", "desc", "unit", int, meter, ("key",))
         kvp = {"key": "value"}
         label_set = meter.get_label_set(kvp)
         handle = metric.get_handle(label_set)
@@ -136,7 +151,7 @@ def test_add(self):
 class TestGauge(unittest.TestCase):
     def test_set(self):
         meter = metrics.Meter()
-        metric = metrics.Gauge("name", "desc", "unit", int, ("key",))
+        metric = metrics.Gauge("name", "desc", "unit", int, meter, ("key",))
         kvp = {"key": "value"}
         label_set = meter.get_label_set(kvp)
         handle = metric.get_handle(label_set)
@@ -149,7 +164,7 @@ def test_set(self):
 class TestMeasure(unittest.TestCase):
     def test_record(self):
         meter = metrics.Meter()
-        metric = metrics.Measure("name", "desc", "unit", int, ("key",))
+        metric = metrics.Measure("name", "desc", "unit", int, meter, ("key",))
         kvp = {"key": "value"}
         label_set = meter.get_label_set(kvp)
         handle = metric.get_handle(label_set)

From 7e9e7ad400edf8bda7ddbc695624de1c52876ee4 Mon Sep 17 00:00:00 2001
From: Leighton <lechen@microsoft.com>
Date: Thu, 14 Nov 2019 18:39:30 -0800
Subject: [PATCH 07/15] fix test

---
 opentelemetry-sdk/tests/metrics/export/test_export.py | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/opentelemetry-sdk/tests/metrics/export/test_export.py b/opentelemetry-sdk/tests/metrics/export/test_export.py
index ca8e8a36311..4d8e6df8575 100644
--- a/opentelemetry-sdk/tests/metrics/export/test_export.py
+++ b/opentelemetry-sdk/tests/metrics/export/test_export.py
@@ -22,19 +22,22 @@
 class TestConsoleMetricsExporter(unittest.TestCase):
     # pylint: disable=no-self-use
     def test_export(self):
+        meter = metrics.Meter()
         exporter = ConsoleMetricsExporter()
         metric = metrics.Counter(
             "available memory",
             "available memory",
             "bytes",
             int,
+            meter,
             ("environment",),
         )
-        label_values = ("staging",)
-        handle = metric.get_handle(label_values)
+        kvp = {"environment": "staging"}
+        label_set = meter.get_label_set(kvp)
+        handle = metric.get_handle(label_set)
         result = '{}(data="{}", label_values="{}", metric_data={})'.format(
-            ConsoleMetricsExporter.__name__, metric, label_values, handle
+            ConsoleMetricsExporter.__name__, metric, label_set, handle
         )
         with mock.patch("sys.stdout") as mock_stdout:
-            exporter.export([(metric, label_values)])
+            exporter.export([(metric, label_set)])
             mock_stdout.write.assert_any_call(result)

From f2842ffcb71c35b55b8df4b884feca8563875df3 Mon Sep 17 00:00:00 2001
From: Leighton <lechen@microsoft.com>
Date: Fri, 15 Nov 2019 14:41:57 -0800
Subject: [PATCH 08/15] lint

---
 .../src/opentelemetry/sdk/metrics/__init__.py | 10 ++++++----
 .../tests/metrics/test_metrics.py             | 20 ++++++++++++++-----
 2 files changed, 21 insertions(+), 9 deletions(-)

diff --git a/opentelemetry-sdk/src/opentelemetry/sdk/metrics/__init__.py b/opentelemetry-sdk/src/opentelemetry/sdk/metrics/__init__.py
index f9db54b0db4..4d1e0343e19 100644
--- a/opentelemetry-sdk/src/opentelemetry/sdk/metrics/__init__.py
+++ b/opentelemetry-sdk/src/opentelemetry/sdk/metrics/__init__.py
@@ -25,10 +25,12 @@
 class LabelSet(metrics_api.LabelSet):
     """See `opentelemetry.metrics.LabelSet."""
 
-    def __init__(self,
-                 meter: "Meter" = None,
-                 labels: Dict[str, str] = None,
-                 encoded: str = ""):
+    def __init__(
+        self,
+        meter: "Meter" = None,
+        labels: Dict[str, str] = None,
+        encoded: str = "",
+    ):
         self.meter = meter
         self.labels = labels
         self.encoded = encoded
diff --git a/opentelemetry-sdk/tests/metrics/test_metrics.py b/opentelemetry-sdk/tests/metrics/test_metrics.py
index 3f060c4e1b4..2213459911f 100644
--- a/opentelemetry-sdk/tests/metrics/test_metrics.py
+++ b/opentelemetry-sdk/tests/metrics/test_metrics.py
@@ -27,7 +27,9 @@ def test_extends_api(self):
     def test_record_batch(self):
         meter = metrics.Meter()
         label_keys = ("key1",)
-        counter = metrics.Counter("name", "desc", "unit", float, meter,label_keys)
+        counter = metrics.Counter(
+            "name", "desc", "unit", float, meter, label_keys
+        )
         kvp = {"key1": "value1"}
         label_set = meter.get_label_set(kvp)
         record_tuples = [(counter, 1.0)]
@@ -39,9 +41,13 @@ def test_record_batch_multiple(self):
         label_keys = ("key1", "key2", "key3")
         kvp = {"key1": "value1", "key2": "value2", "key3": "value3"}
         label_set = meter.get_label_set(kvp)
-        counter = metrics.Counter("name", "desc", "unit", float, meter, label_keys)
+        counter = metrics.Counter(
+            "name", "desc", "unit", float, meter, label_keys
+        )
         gauge = metrics.Gauge("name", "desc", "unit", int, label_keys)
-        measure = metrics.Measure("name", "desc", "unit", float, meter, label_keys)
+        measure = metrics.Measure(
+            "name", "desc", "unit", float, meter, label_keys
+        )
         record_tuples = [(counter, 1.0), (gauge, 5), (measure, 3.0)]
         meter.record_batch(label_set, record_tuples)
         self.assertEqual(counter.get_handle(label_set).data, 1.0)
@@ -53,7 +59,9 @@ def test_record_batch_exists(self):
         label_keys = ("key1",)
         kvp = {"key1": "value1"}
         label_set = meter.get_label_set(kvp)
-        counter = metrics.Counter("name", "desc", "unit", float, meter, label_keys)
+        counter = metrics.Counter(
+            "name", "desc", "unit", float, meter, label_keys
+        )
         counter.add(label_set, 1.0)
         handle = counter.get_handle(label_set)
         record_tuples = [(counter, 1.0)]
@@ -133,7 +141,9 @@ def test_label_set_for_different(self):
         metric = metrics.Counter("name", "desc", "unit", int, meter, ("key",))
         kvp = {"environment": "staging", "a": "z"}
         label_set = meter2.get_label_set(kvp)
-        self.assertEqual(metric._label_set_for(label_set), metrics.EMPTY_LABEL_SET)
+        self.assertEqual(
+            metric._label_set_for(label_set), metrics.EMPTY_LABEL_SET
+        )
 
 
 class TestCounter(unittest.TestCase):

From f390f879cb48e19a2a96ea6c77b8ba56e70ac4f7 Mon Sep 17 00:00:00 2001
From: Leighton <lechen@microsoft.com>
Date: Fri, 15 Nov 2019 15:00:58 -0800
Subject: [PATCH 09/15] lint

---
 opentelemetry-sdk/src/opentelemetry/sdk/metrics/__init__.py | 2 +-
 opentelemetry-sdk/tests/metrics/test_metrics.py             | 2 ++
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/opentelemetry-sdk/src/opentelemetry/sdk/metrics/__init__.py b/opentelemetry-sdk/src/opentelemetry/sdk/metrics/__init__.py
index 4d1e0343e19..461f4bbb5f4 100644
--- a/opentelemetry-sdk/src/opentelemetry/sdk/metrics/__init__.py
+++ b/opentelemetry-sdk/src/opentelemetry/sdk/metrics/__init__.py
@@ -21,7 +21,7 @@
 
 logger = logging.getLogger(__name__)
 
-
+# pylint: disable=redefined-outer-name
 class LabelSet(metrics_api.LabelSet):
     """See `opentelemetry.metrics.LabelSet."""
 
diff --git a/opentelemetry-sdk/tests/metrics/test_metrics.py b/opentelemetry-sdk/tests/metrics/test_metrics.py
index 2213459911f..6e8a7f157d4 100644
--- a/opentelemetry-sdk/tests/metrics/test_metrics.py
+++ b/opentelemetry-sdk/tests/metrics/test_metrics.py
@@ -133,6 +133,7 @@ def test_label_set_for(self):
         metric = metrics.Counter("name", "desc", "unit", int, meter, ("key",))
         kvp = {"environment": "staging", "a": "z"}
         label_set = meter.get_label_set(kvp)
+        # pylint: disable=protected-access
         self.assertEqual(metric._label_set_for(label_set), label_set)
 
     def test_label_set_for_different(self):
@@ -141,6 +142,7 @@ def test_label_set_for_different(self):
         metric = metrics.Counter("name", "desc", "unit", int, meter, ("key",))
         kvp = {"environment": "staging", "a": "z"}
         label_set = meter2.get_label_set(kvp)
+        # pylint: disable=protected-access
         self.assertEqual(
             metric._label_set_for(label_set), metrics.EMPTY_LABEL_SET
         )

From 4c050d2d69848527455aeca234748def90bffb11 Mon Sep 17 00:00:00 2001
From: Leighton <lechen@microsoft.com>
Date: Fri, 15 Nov 2019 15:15:17 -0800
Subject: [PATCH 10/15] lint

---
 opentelemetry-sdk/src/opentelemetry/sdk/metrics/__init__.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/opentelemetry-sdk/src/opentelemetry/sdk/metrics/__init__.py b/opentelemetry-sdk/src/opentelemetry/sdk/metrics/__init__.py
index 461f4bbb5f4..3bdc6719e73 100644
--- a/opentelemetry-sdk/src/opentelemetry/sdk/metrics/__init__.py
+++ b/opentelemetry-sdk/src/opentelemetry/sdk/metrics/__init__.py
@@ -21,6 +21,7 @@
 
 logger = logging.getLogger(__name__)
 
+
 # pylint: disable=redefined-outer-name
 class LabelSet(metrics_api.LabelSet):
     """See `opentelemetry.metrics.LabelSet."""

From 2fe06ca8b90a145e07e6914bb1cdcac12bb9194d Mon Sep 17 00:00:00 2001
From: Leighton <lechen@microsoft.com>
Date: Mon, 18 Nov 2019 12:00:40 -0800
Subject: [PATCH 11/15] Address comments

---
 opentelemetry-api/tests/metrics/test_metrics.py             | 4 ++--
 opentelemetry-sdk/src/opentelemetry/sdk/metrics/__init__.py | 4 ++--
 opentelemetry-sdk/tests/metrics/test_metrics.py             | 2 +-
 3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/opentelemetry-api/tests/metrics/test_metrics.py b/opentelemetry-api/tests/metrics/test_metrics.py
index 77031d614de..f8610a6fa4c 100644
--- a/opentelemetry-api/tests/metrics/test_metrics.py
+++ b/opentelemetry-api/tests/metrics/test_metrics.py
@@ -39,8 +39,8 @@ def test_get_label_set(self):
 class TestMetrics(unittest.TestCase):
     def test_default(self):
         default = metrics.DefaultMetric()
-        label_set = metrics.LabelSet()
-        handle = default.get_handle(label_set)
+        default_ls = metrics.DefaultLabelSet()
+        handle = default.get_handle(default_ls)
         self.assertIsInstance(handle, metrics.DefaultMetricHandle)
 
     def test_counter(self):
diff --git a/opentelemetry-sdk/src/opentelemetry/sdk/metrics/__init__.py b/opentelemetry-sdk/src/opentelemetry/sdk/metrics/__init__.py
index 3bdc6719e73..395669de1e0 100644
--- a/opentelemetry-sdk/src/opentelemetry/sdk/metrics/__init__.py
+++ b/opentelemetry-sdk/src/opentelemetry/sdk/metrics/__init__.py
@@ -330,8 +330,8 @@ def get_label_set(self, labels: Dict[str, str]):
             return EMPTY_LABEL_SET
         sorted_labels = OrderedDict(sorted(labels.items()))
         # Uses statsd encoding for labels
-        encoded = "|#" + ",".join(
-            "%s:%s" % (key, value) for (key, value) in sorted_labels.items()
+        encoded = "," + ",".join(
+            "%s=%s" % (key, value) for (key, value) in sorted_labels.items()
         )
         # If LabelSet exists for this meter in memory, use existing one
         if not self.labels.get(encoded):
diff --git a/opentelemetry-sdk/tests/metrics/test_metrics.py b/opentelemetry-sdk/tests/metrics/test_metrics.py
index 6e8a7f157d4..3b1b66b2b77 100644
--- a/opentelemetry-sdk/tests/metrics/test_metrics.py
+++ b/opentelemetry-sdk/tests/metrics/test_metrics.py
@@ -100,7 +100,7 @@ def test_get_label_set(self):
         meter = metrics.Meter()
         kvp = {"environment": "staging", "a": "z"}
         label_set = meter.get_label_set(kvp)
-        encoding = "|#a:z,environment:staging"
+        encoding = ",a=z,environment=staging"
         self.assertEqual(label_set.encoded, encoding)
 
     def test_get_label_set_empty(self):

From 30e5e5a04a002dc3ec5029b697271ca0198c7a69 Mon Sep 17 00:00:00 2001
From: Leighton <lechen@microsoft.com>
Date: Tue, 19 Nov 2019 11:16:13 -0800
Subject: [PATCH 12/15] abc

---
 opentelemetry-api/src/opentelemetry/metrics/__init__.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/opentelemetry-api/src/opentelemetry/metrics/__init__.py b/opentelemetry-api/src/opentelemetry/metrics/__init__.py
index aad70d5ba3d..465020606d2 100644
--- a/opentelemetry-api/src/opentelemetry/metrics/__init__.py
+++ b/opentelemetry-api/src/opentelemetry/metrics/__init__.py
@@ -26,6 +26,7 @@
 
 
 """
+import abc
 from typing import Callable, Dict, Optional, Sequence, Tuple, Type, TypeVar
 
 from opentelemetry.util import loader
@@ -67,7 +68,7 @@ def record(self, value: ValueT) -> None:
         """
 
 
-class LabelSet:
+class LabelSet(abc.ABC):
     """A canonicalized set of labels useful for preaggregation
 
     Re-usable LabelSet objects provide a potential optimization for scenarios

From f37512828711fbe54f4eea76c899d6530290f16a Mon Sep 17 00:00:00 2001
From: Leighton <lechen@microsoft.com>
Date: Wed, 27 Nov 2019 16:51:07 -0800
Subject: [PATCH 13/15] Apply Chris' changes

---
 .../src/opentelemetry/sdk/metrics/__init__.py | 54 +++----------------
 .../tests/metrics/test_metrics.py             | 39 ++++----------
 2 files changed, 18 insertions(+), 75 deletions(-)

diff --git a/opentelemetry-sdk/src/opentelemetry/sdk/metrics/__init__.py b/opentelemetry-sdk/src/opentelemetry/sdk/metrics/__init__.py
index 395669de1e0..fcb7e6207e5 100644
--- a/opentelemetry-sdk/src/opentelemetry/sdk/metrics/__init__.py
+++ b/opentelemetry-sdk/src/opentelemetry/sdk/metrics/__init__.py
@@ -26,15 +26,8 @@
 class LabelSet(metrics_api.LabelSet):
     """See `opentelemetry.metrics.LabelSet."""
 
-    def __init__(
-        self,
-        meter: "Meter" = None,
-        labels: Dict[str, str] = None,
-        encoded: str = "",
-    ):
-        self.meter = meter
+    def __init__(self, labels: Dict[str, str] = None):
         self.labels = labels
-        self.encoded = encoded
 
 
 class BaseHandle:
@@ -110,7 +103,6 @@ def __init__(
         description: str,
         unit: str,
         value_type: Type[metrics_api.ValueT],
-        meter: "Meter",
         label_keys: Sequence[str] = None,
         enabled: bool = True,
         monotonic: bool = False,
@@ -119,7 +111,6 @@ def __init__(
         self.description = description
         self.unit = unit
         self.value_type = value_type
-        self.meter = meter
         self.label_keys = label_keys
         self.enabled = enabled
         self.monotonic = monotonic
@@ -127,31 +118,14 @@ def __init__(
 
     def get_handle(self, label_set: LabelSet) -> BaseHandle:
         """See `opentelemetry.metrics.Metric.get_handle`."""
-        lable_set_for = self._label_set_for(label_set)
-        handle = self.handles.get(lable_set_for.encoded)
+        handle = self.handles.get(label_set)
         if not handle:
             handle = self.HANDLE_TYPE(
                 self.value_type, self.enabled, self.monotonic
             )
-        self.handles[lable_set_for.encoded] = handle
+        self.handles[label_set] = handle
         return handle
 
-    def _label_set_for(self, label_set: LabelSet) -> LabelSet:
-        """Returns an appropriate `LabelSet` based off this metric's `meter`
-
-        If this metric's `meter` is the same as label_set's meter, that means
-        label_set was created from this metric's `meter` instance and the
-        proper handle can be found. If not, label_set was created using a
-        different `meter` implementation, in which the metric cannot interpret.
-        In this case, return the `EMPTY_LABEL_SET`.
-
-        Args:
-            label_set: The `LabelSet` to check for the same `Meter` implentation.
-        """
-        if label_set.meter and label_set.meter is self.meter:
-            return label_set
-        return EMPTY_LABEL_SET
-
     def __repr__(self):
         return '{}(name="{}", description={})'.format(
             type(self).__name__, self.name, self.description
@@ -176,7 +150,6 @@ def __init__(
         description: str,
         unit: str,
         value_type: Type[metrics_api.ValueT],
-        meter: "Meter",
         label_keys: Sequence[str] = None,
         enabled: bool = True,
         monotonic: bool = True,
@@ -186,7 +159,6 @@ def __init__(
             description,
             unit,
             value_type,
-            meter,
             label_keys=label_keys,
             enabled=enabled,
             monotonic=monotonic,
@@ -214,7 +186,6 @@ def __init__(
         description: str,
         unit: str,
         value_type: Type[metrics_api.ValueT],
-        meter: "Meter",
         label_keys: Sequence[str] = None,
         enabled: bool = True,
         monotonic: bool = False,
@@ -224,7 +195,6 @@ def __init__(
             description,
             unit,
             value_type,
-            meter,
             label_keys=label_keys,
             enabled=enabled,
             monotonic=monotonic,
@@ -252,7 +222,6 @@ def __init__(
         description: str,
         unit: str,
         value_type: Type[metrics_api.ValueT],
-        meter: "Meter",
         label_keys: Sequence[str] = None,
         enabled: bool = False,
         monotonic: bool = False,
@@ -262,7 +231,6 @@ def __init__(
             description,
             unit,
             value_type,
-            meter,
             label_keys=label_keys,
             enabled=enabled,
             monotonic=monotonic,
@@ -275,7 +243,7 @@ def record(self, label_set: LabelSet, value: metrics_api.ValueT) -> None:
     UPDATE_FUNCTION = record
 
 
-# Singleton of meter.get_label_set() with zero arguments
+# Used when getting a LabelSet with no key/values
 EMPTY_LABEL_SET = LabelSet()
 
 
@@ -312,7 +280,6 @@ def create_metric(
             description,
             unit,
             value_type,
-            self,
             label_keys=label_keys,
             enabled=enabled,
             monotonic=monotonic,
@@ -328,16 +295,11 @@ def get_label_set(self, labels: Dict[str, str]):
         """
         if len(labels) == 0:
             return EMPTY_LABEL_SET
-        sorted_labels = OrderedDict(sorted(labels.items()))
-        # Uses statsd encoding for labels
-        encoded = "," + ",".join(
-            "%s=%s" % (key, value) for (key, value) in sorted_labels.items()
-        )
+        # Use simple encoding for now until encoding API is implemented
+        encoded = tuple(sorted(labels.items()))
         # If LabelSet exists for this meter in memory, use existing one
-        if not self.labels.get(encoded):
-            self.labels[encoded] = LabelSet(
-                self, labels=sorted_labels, encoded=encoded
-            )
+        if not encoded in self.labels:
+            self.labels[encoded] = LabelSet(labels=labels)
         return self.labels[encoded]
 
 
diff --git a/opentelemetry-sdk/tests/metrics/test_metrics.py b/opentelemetry-sdk/tests/metrics/test_metrics.py
index 3b1b66b2b77..81e6dd2c9d5 100644
--- a/opentelemetry-sdk/tests/metrics/test_metrics.py
+++ b/opentelemetry-sdk/tests/metrics/test_metrics.py
@@ -72,7 +72,7 @@ def test_record_batch_exists(self):
     def test_create_metric(self):
         meter = metrics.Meter()
         counter = meter.create_metric(
-            "name", "desc", "unit", int, metrics.Counter, meter, ()
+            "name", "desc", "unit", int, metrics.Counter, ()
         )
         self.assertTrue(isinstance(counter, metrics.Counter))
         self.assertEqual(counter.value_type, int)
@@ -81,7 +81,7 @@ def test_create_metric(self):
     def test_create_gauge(self):
         meter = metrics.Meter()
         gauge = meter.create_metric(
-            "name", "desc", "unit", float, metrics.Gauge, meter, ()
+            "name", "desc", "unit", float, metrics.Gauge, ()
         )
         self.assertTrue(isinstance(gauge, metrics.Gauge))
         self.assertEqual(gauge.value_type, float)
@@ -90,7 +90,7 @@ def test_create_gauge(self):
     def test_create_measure(self):
         meter = metrics.Meter()
         measure = meter.create_metric(
-            "name", "desc", "unit", float, metrics.Measure, meter, ()
+            "name", "desc", "unit", float, metrics.Measure, ()
         )
         self.assertTrue(isinstance(measure, metrics.Measure))
         self.assertEqual(measure.value_type, float)
@@ -100,8 +100,8 @@ def test_get_label_set(self):
         meter = metrics.Meter()
         kvp = {"environment": "staging", "a": "z"}
         label_set = meter.get_label_set(kvp)
-        encoding = ",a=z,environment=staging"
-        self.assertEqual(label_set.encoded, encoding)
+        encoded = tuple(sorted(kvp.items()))
+        self.assertIs(meter.labels[encoded], label_set)
 
     def test_get_label_set_empty(self):
         meter = metrics.Meter()
@@ -114,7 +114,7 @@ def test_get_label_set_exists(self):
         kvp = {"environment": "staging", "a": "z"}
         label_set = meter.get_label_set(kvp)
         label_set2 = meter.get_label_set(kvp)
-        self.assertEqual(label_set, label_set2)
+        self.assertIs(label_set, label_set2)
 
 
 class TestMetric(unittest.TestCase):
@@ -126,32 +126,13 @@ def test_get_handle(self):
             kvp = {"key": "value"}
             label_set = meter.get_label_set(kvp)
             handle = metric.get_handle(label_set)
-            self.assertEqual(metric.handles.get(label_set.encoded), handle)
-
-    def test_label_set_for(self):
-        meter = metrics.Meter()
-        metric = metrics.Counter("name", "desc", "unit", int, meter, ("key",))
-        kvp = {"environment": "staging", "a": "z"}
-        label_set = meter.get_label_set(kvp)
-        # pylint: disable=protected-access
-        self.assertEqual(metric._label_set_for(label_set), label_set)
-
-    def test_label_set_for_different(self):
-        meter = metrics.Meter()
-        meter2 = metrics.Meter()
-        metric = metrics.Counter("name", "desc", "unit", int, meter, ("key",))
-        kvp = {"environment": "staging", "a": "z"}
-        label_set = meter2.get_label_set(kvp)
-        # pylint: disable=protected-access
-        self.assertEqual(
-            metric._label_set_for(label_set), metrics.EMPTY_LABEL_SET
-        )
+            self.assertEqual(metric.handles.get(label_set), handle)
 
 
 class TestCounter(unittest.TestCase):
     def test_add(self):
         meter = metrics.Meter()
-        metric = metrics.Counter("name", "desc", "unit", int, meter, ("key",))
+        metric = metrics.Counter("name", "desc", "unit", int, ("key",))
         kvp = {"key": "value"}
         label_set = meter.get_label_set(kvp)
         handle = metric.get_handle(label_set)
@@ -163,7 +144,7 @@ def test_add(self):
 class TestGauge(unittest.TestCase):
     def test_set(self):
         meter = metrics.Meter()
-        metric = metrics.Gauge("name", "desc", "unit", int, meter, ("key",))
+        metric = metrics.Gauge("name", "desc", "unit", int, ("key",))
         kvp = {"key": "value"}
         label_set = meter.get_label_set(kvp)
         handle = metric.get_handle(label_set)
@@ -176,7 +157,7 @@ def test_set(self):
 class TestMeasure(unittest.TestCase):
     def test_record(self):
         meter = metrics.Meter()
-        metric = metrics.Measure("name", "desc", "unit", int, meter, ("key",))
+        metric = metrics.Measure("name", "desc", "unit", int, ("key",))
         kvp = {"key": "value"}
         label_set = meter.get_label_set(kvp)
         handle = metric.get_handle(label_set)

From ce33371ecf117a5e53f0d39dd62d92e8597d4e6f Mon Sep 17 00:00:00 2001
From: Leighton <lechen@microsoft.com>
Date: Wed, 27 Nov 2019 17:04:29 -0800
Subject: [PATCH 14/15] fix lint

---
 opentelemetry-sdk/src/opentelemetry/sdk/metrics/__init__.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/opentelemetry-sdk/src/opentelemetry/sdk/metrics/__init__.py b/opentelemetry-sdk/src/opentelemetry/sdk/metrics/__init__.py
index fcb7e6207e5..bb495bc1be3 100644
--- a/opentelemetry-sdk/src/opentelemetry/sdk/metrics/__init__.py
+++ b/opentelemetry-sdk/src/opentelemetry/sdk/metrics/__init__.py
@@ -298,7 +298,7 @@ def get_label_set(self, labels: Dict[str, str]):
         # Use simple encoding for now until encoding API is implemented
         encoded = tuple(sorted(labels.items()))
         # If LabelSet exists for this meter in memory, use existing one
-        if not encoded in self.labels:
+        if encoded not in self.labels:
             self.labels[encoded] = LabelSet(labels=labels)
         return self.labels[encoded]
 

From 792449eaa5a68bf9dc6eab827f585e964eb27c50 Mon Sep 17 00:00:00 2001
From: Chris Kleinknecht <libc@google.com>
Date: Mon, 2 Dec 2019 23:58:12 -0500
Subject: [PATCH 15/15] Use mypy==0.740

---
 tox.ini | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tox.ini b/tox.ini
index e0e076fe77d..445ed696ed5 100644
--- a/tox.ini
+++ b/tox.ini
@@ -22,7 +22,7 @@ python =
 deps =
   test: pytest
   coverage: pytest-cov
-  mypy,mypyinstalled: mypy~=0.740
+  mypy,mypyinstalled: mypy==0.740
 
 setenv =
   mypy: MYPYPATH={toxinidir}/opentelemetry-api/src/