1 files changed, 60 insertions, 0 deletions
diff --git a/api/src/main/java/io/opencensus/metrics/MetricRegistry.java b/api/src/main/java/io/opencensus/metrics/MetricRegistry.java
index 557f886a..5be15594 100644
--- a/api/src/main/java/io/opencensus/metrics/MetricRegistry.java
+++ b/api/src/main/java/io/opencensus/metrics/MetricRegistry.java
@@ -17,6 +17,8 @@
 package io.opencensus.metrics;
 
 import io.opencensus.common.ExperimentalApi;
+import io.opencensus.common.ToDoubleFunction;
+import io.opencensus.common.ToLongFunction;
 import io.opencensus.internal.Utils;
 import java.util.List;
 
@@ -63,6 +65,40 @@ public abstract class MetricRegistry {
   public abstract DoubleGauge addDoubleGauge(
       String name, String description, String unit, List<LabelKey> labelKeys);
 
+  /**
+   * Builds a new derived long gauge to be added to the registry. This is more convenient form when
+   * you want to define a gauge by executing a {@link ToLongFunction} on an object.
+   *
+   * @param name the name of the metric.
+   * @param description the description of the metric.
+   * @param unit the unit of the metric.
+   * @param labelKeys the list of the label keys.
+   * @throws NullPointerException if {@code labelKeys} is null OR any element of {@code labelKeys}
+   *     is null OR {@code name}, {@code description}, {@code unit} is null.
+   * @throws IllegalArgumentException if different metric with the same name already registered.
+   * @since 0.17
+   */
+  @ExperimentalApi
+  public abstract DerivedLongGauge addDerivedLongGauge(
+      String name, String description, String unit, List<LabelKey> labelKeys);
+
+  /**
+   * Builds a new derived double gauge to be added to the registry. This is more convenient form
+   * when you want to define a gauge by executing a {@link ToDoubleFunction} on an object.
+   *
+   * @param name the name of the metric.
+   * @param description the description of the metric.
+   * @param unit the unit of the metric.
+   * @param labelKeys the list of the label keys.
+   * @throws NullPointerException if {@code labelKeys} is null OR any element of {@code labelKeys}
+   *     is null OR {@code name}, {@code description}, {@code unit} is null.
+   * @throws IllegalArgumentException if different metric with the same name already registered.
+   * @since 0.17
+   */
+  @ExperimentalApi
+  public abstract DerivedDoubleGauge addDerivedDoubleGauge(
+      String name, String description, String unit, List<LabelKey> labelKeys);
+
   static MetricRegistry newNoopMetricRegistry() {
     return new NoopMetricRegistry();
   }
@@ -92,5 +128,29 @@ public abstract class MetricRegistry {
           Utils.checkNotNull(unit, "unit"),
           labelKeys);
     }
+
+    @Override
+    public DerivedLongGauge addDerivedLongGauge(
+        String name, String description, String unit, List<LabelKey> labelKeys) {
+      Utils.checkListElementNotNull(
+          Utils.checkNotNull(labelKeys, "labelKeys"), "labelKey element should not be null.");
+      return DerivedLongGauge.newNoopDerivedLongGauge(
+          Utils.checkNotNull(name, "name"),
+          Utils.checkNotNull(description, "description"),
+          Utils.checkNotNull(unit, "unit"),
+          labelKeys);
+    }
+
+    @Override
+    public DerivedDoubleGauge addDerivedDoubleGauge(
+        String name, String description, String unit, List<LabelKey> labelKeys) {
+      Utils.checkListElementNotNull(
+          Utils.checkNotNull(labelKeys, "labelKeys"), "labelKey element should not be null.");
+      return DerivedDoubleGauge.newNoopDerivedDoubleGauge(
+          Utils.checkNotNull(name, "name"),
+          Utils.checkNotNull(description, "description"),
+          Utils.checkNotNull(unit, "unit"),
+          labelKeys);
+    }
   }
 }