Add initial implementation for Observers

sdk/src/main/java/io/opentelemetry/sdk/metrics/BaseInstrument.java

@@ -16,13 +16,11 @@
 
 package io.opentelemetry.sdk.metrics;
 
-import io.opentelemetry.metrics.InstrumentWithBinding;
-import io.opentelemetry.metrics.LabelSet;
+import io.opentelemetry.metrics.Instrument;
 import java.util.List;
 import java.util.Map;
 
-// TODO: add a BaseInstrument and a BaseInstrumentWithBounds.
-abstract class BaseInstrument<B> implements InstrumentWithBinding<B> {
+abstract class BaseInstrument implements Instrument {
 
   private final String name;
   private final String description;
@@ -37,19 +35,6 @@ abstract class BaseInstrument<B> implements InstrumentWithBinding<B> {
     this.labelKeys = labelKeys;
   }
 
-  abstract B createBoundInstrument(LabelSet labelSet);
-
-  @Override
-  public B bind(LabelSet labelSet) {
-    return createBoundInstrument(labelSet);
-    // todo: associate with an aggregator/accumulator
-  }
-
-  @Override
-  public void unbind(B boundInstrument) {
-    // todo: pass through to an aggregator/accumulator
-  }
-
   @Override
   public boolean equals(Object o) {
     if (this == o) {
@@ -59,7 +44,7 @@ public boolean equals(Object o) {
       return false;
     }
 
-    BaseInstrument<?> that = (BaseInstrument<?>) o;
+    BaseInstrument that = (BaseInstrument) o;
 
     if (name != null ? !name.equals(that.name) : that.name != null) {
       return false;

sdk/src/main/java/io/opentelemetry/sdk/metrics/BaseInstrumentWithBinding.java

@@ -0,0 +1,44 @@
+/*
+ * Copyright 2020, OpenTelemetry Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.opentelemetry.sdk.metrics;
+
+import io.opentelemetry.metrics.InstrumentWithBinding;
+import io.opentelemetry.metrics.LabelSet;
+import java.util.List;
+import java.util.Map;
+
+abstract class BaseInstrumentWithBinding<B> extends BaseInstrument
+    implements InstrumentWithBinding<B> {
+
+  BaseInstrumentWithBinding(
+      String name, String description, Map<String, String> constantLabels, List<String> labelKeys) {
+    super(name, description, constantLabels, labelKeys);
+  }
+
+  abstract B createBoundInstrument(LabelSet labelSet);
+
+  @Override
+  public B bind(LabelSet labelSet) {
+    return createBoundInstrument(labelSet);
+    // todo: associate with an aggregator/accumulator
+  }
+
+  @Override
+  public void unbind(B boundInstrument) {
+    // todo: pass through to an aggregator/accumulator
+  }
+}

sdk/src/main/java/io/opentelemetry/sdk/metrics/DoubleCounterSdk.java

@@ -22,7 +22,8 @@
 import java.util.List;
 import java.util.Map;
 
-final class DoubleCounterSdk extends BaseInstrument<BoundDoubleCounter> implements DoubleCounter {
+final class DoubleCounterSdk extends BaseInstrumentWithBinding<BoundDoubleCounter>
+    implements DoubleCounter {
 
   private final boolean monotonic;
 

sdk/src/main/java/io/opentelemetry/sdk/metrics/DoubleMeasureSdk.java

@@ -22,7 +22,8 @@
 import java.util.List;
 import java.util.Map;
 
-final class DoubleMeasureSdk extends BaseInstrument<BoundDoubleMeasure> implements DoubleMeasure {
+final class DoubleMeasureSdk extends BaseInstrumentWithBinding<BoundDoubleMeasure>
+    implements DoubleMeasure {
 
   private final boolean absolute;
 

sdk/src/main/java/io/opentelemetry/sdk/metrics/DoubleObserverSdk.java

@@ -0,0 +1,88 @@
+/*
+ * Copyright 2020, OpenTelemetry Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.opentelemetry.sdk.metrics;
+
+import io.opentelemetry.metrics.DoubleObserver;
+import java.util.List;
+import java.util.Map;
+
+final class DoubleObserverSdk extends BaseInstrument implements DoubleObserver {
+  private final boolean monotonic;
+
+  DoubleObserverSdk(
+      String name,
+      String description,
+      Map<String, String> constantLabels,
+      List<String> labelKeys,
+      boolean monotonic) {
+    super(name, description, constantLabels, labelKeys);
+    this.monotonic = monotonic;
+  }
+
+  @Override
+  public void setCallback(Callback<DoubleObserver.ResultDoubleObserver> metricUpdater) {
+    throw new UnsupportedOperationException("to be implemented");
+  }
+
+  @Override
+  public boolean equals(Object o) {
+    if (this == o) {
+      return true;
+    }
+    if (!(o instanceof DoubleObserverSdk)) {
+      return false;
+    }
+    if (!super.equals(o)) {
+      return false;
+    }
+
+    DoubleObserverSdk that = (DoubleObserverSdk) o;
+
+    return monotonic == that.monotonic;
+  }
+
+  @Override
+  public int hashCode() {
+    int result = super.hashCode();
+    result = 31 * result + (monotonic ? 1 : 0);
+    return result;
+  }
+
+  static DoubleObserver.Builder builder(String name) {
+    return new Builder(name);
+  }
+
+  private static final class Builder
+      extends AbstractObserverBuilder<DoubleObserver.Builder, DoubleObserver>
+      implements DoubleObserver.Builder {
+
+    private Builder(String name) {
+      super(name);
+    }
+
+    @Override
+    Builder getThis() {
+      return this;
+    }
+
+    @Override
+    public DoubleObserver build() {
+      return new DoubleObserverSdk(
+          getName(), getDescription(), getConstantLabels(), getLabelKeys(), isMonotonic());
+    }
+  }
+}

sdk/src/main/java/io/opentelemetry/sdk/metrics/LongCounterSdk.java

@@ -22,7 +22,8 @@
 import java.util.List;
 import java.util.Map;
 
-final class LongCounterSdk extends BaseInstrument<BoundLongCounter> implements LongCounter {
+final class LongCounterSdk extends BaseInstrumentWithBinding<BoundLongCounter>
+    implements LongCounter {
 
   private final boolean monotonic;
 

sdk/src/main/java/io/opentelemetry/sdk/metrics/LongMeasureSdk.java

@@ -22,7 +22,8 @@
 import java.util.List;
 import java.util.Map;
 
-final class LongMeasureSdk extends BaseInstrument<BoundLongMeasure> implements LongMeasure {
+final class LongMeasureSdk extends BaseInstrumentWithBinding<BoundLongMeasure>
+    implements LongMeasure {
 
   private final boolean absolute;
 

sdk/src/main/java/io/opentelemetry/sdk/metrics/LongObserverSdk.java

@@ -0,0 +1,88 @@
+/*
+ * Copyright 2020, OpenTelemetry Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.opentelemetry.sdk.metrics;
+
+import io.opentelemetry.metrics.LongObserver;
+import java.util.List;
+import java.util.Map;
+
+final class LongObserverSdk extends BaseInstrument implements LongObserver {
+  private final boolean monotonic;
+
+  LongObserverSdk(
+      String name,
+      String description,
+      Map<String, String> constantLabels,
+      List<String> labelKeys,
+      boolean monotonic) {
+    super(name, description, constantLabels, labelKeys);
+    this.monotonic = monotonic;
+  }
+
+  @Override
+  public void setCallback(Callback<LongObserver.ResultLongObserver> metricUpdater) {
+    throw new UnsupportedOperationException("to be implemented");
+  }
+
+  @Override
+  public boolean equals(Object o) {
+    if (this == o) {
+      return true;
+    }
+    if (!(o instanceof LongObserverSdk)) {
+      return false;
+    }
+    if (!super.equals(o)) {
+      return false;
+    }
+
+    LongObserverSdk that = (LongObserverSdk) o;
+
+    return monotonic == that.monotonic;
+  }
+
+  @Override
+  public int hashCode() {
+    int result = super.hashCode();
+    result = 31 * result + (monotonic ? 1 : 0);
+    return result;
+  }
+
+  static LongObserver.Builder builder(String name) {
+    return new Builder(name);
+  }
+
+  private static final class Builder
+      extends AbstractObserverBuilder<LongObserver.Builder, LongObserver>
+      implements LongObserver.Builder {
+
+    private Builder(String name) {
+      super(name);
+    }
+
+    @Override
+    Builder getThis() {
+      return this;
+    }
+
+    @Override
+    public LongObserver build() {
+      return new LongObserverSdk(
+          getName(), getDescription(), getConstantLabels(), getLabelKeys(), isMonotonic());
+    }
+  }
+}

sdk/src/main/java/io/opentelemetry/sdk/metrics/MeterSdk.java

@@ -80,12 +80,12 @@ public LongMeasure.Builder longMeasureBuilder(String name) {
 
   @Override
   public DoubleObserver.Builder doubleObserverBuilder(String name) {
-    throw new UnsupportedOperationException("to be implemented");
+    return DoubleObserverSdk.builder(name);
   }
 
   @Override
   public LongObserver.Builder longObserverBuilder(String name) {
-    throw new UnsupportedOperationException("to be implemented");
+    return LongObserverSdk.builder(name);
   }
 
   @Override

sdk/src/test/java/io/opentelemetry/sdk/metrics/MeterSdkTest.java

@@ -21,8 +21,10 @@
 import com.google.common.collect.ImmutableMap;
 import io.opentelemetry.metrics.DoubleCounter;
 import io.opentelemetry.metrics.DoubleMeasure;
+import io.opentelemetry.metrics.DoubleObserver;
 import io.opentelemetry.metrics.LongCounter;
 import io.opentelemetry.metrics.LongMeasure;
+import io.opentelemetry.metrics.LongObserver;
 import java.util.Collections;
 import org.junit.Test;
 import org.junit.runner.RunWith;
@@ -68,6 +70,23 @@ public void testLongMeasure() {
     // todo: verify that the MeterSdk has kept track of what has been created, once that's in place
   }
 
+  @Test
+  public void testLongObserver() {
+    LongObserver longObserver =
+        testSdk
+            .longObserverBuilder("testCounter")
+            .setConstantLabels(ImmutableMap.of("sk1", "sv1"))
+            .setLabelKeys(Collections.singletonList("sk1"))
+            .setDescription("My very own counter")
+            .setUnit("metric tonnes")
+            .setMonotonic(true)
+            .build();
+    assertThat(longObserver).isNotNull();
+    assertThat(longObserver).isInstanceOf(LongObserverSdk.class);
+
+    // todo: verify that the MeterSdk has kept track of what has been created, once that's in place
+  }
+
   @Test
   public void testDoubleCounter() {
     DoubleCounter doubleCounter =
@@ -102,6 +121,23 @@ public void testDoubleMeasure() {
     // todo: verify that the MeterSdk has kept track of what has been created, once that's in place
   }
 
+  @Test
+  public void testDoubleObserver() {
+    DoubleObserver doubleObserver =
+        testSdk
+            .doubleObserverBuilder("testCounter")
+            .setConstantLabels(ImmutableMap.of("sk1", "sv1"))
+            .setLabelKeys(Collections.singletonList("sk1"))
+            .setDescription("My very own counter")
+            .setUnit("metric tonnes")
+            .setMonotonic(true)
+            .build();
+    assertThat(doubleObserver).isNotNull();
+    assertThat(doubleObserver).isInstanceOf(DoubleObserverSdk.class);
+
+    // todo: verify that the MeterSdk has kept track of what has been created, once that's in place
+  }
+
   @Test
   public void testLabelSets() {
     assertThat(testSdk.createLabelSet()).isSameInstanceAs(testSdk.createLabelSet());