Extract View configuration interface so it only exposes public API. (#4239)

* Extract View configuration interface so it only exposes public API.

* scare

sdk-extensions/metric-incubator/src/test/java/io/opentelemetry/sdk/viewconfig/ViewConfigTest.java

@@ -16,6 +16,7 @@ import io.opentelemetry.sdk.autoconfigure.spi.ConfigurationException;
 import io.opentelemetry.sdk.metrics.SdkMeterProvider;
 import io.opentelemetry.sdk.metrics.SdkMeterProviderBuilder;
 import io.opentelemetry.sdk.metrics.common.InstrumentType;
+import io.opentelemetry.sdk.metrics.internal.view.ImmutableView;
 import io.opentelemetry.sdk.metrics.internal.view.ViewRegistryBuilder;
 import io.opentelemetry.sdk.metrics.view.Aggregation;
 import io.opentelemetry.sdk.metrics.view.InstrumentSelector;
@@ -114,7 +115,7 @@ class ViewConfigTest {
     assertThat(view.getDescription()).isEqualTo("description");
     assertThat(view.getAggregation()).isEqualTo(Aggregation.sum());
     assertThat(
-            view.getAttributesProcessor()
+            ImmutableView.getAttributesProcessor(view)
                 .process(
                     Attributes.builder()
                         .put("foo", "val")

sdk/metrics/src/debugEnabledTest/java/io/opentelemetry/testing/SourceInfoTest.java

@@ -13,20 +13,21 @@ import io.opentelemetry.sdk.metrics.internal.debug.SourceInfo;
 import io.opentelemetry.sdk.metrics.internal.descriptor.InstrumentDescriptor;
 import io.opentelemetry.sdk.metrics.internal.descriptor.MetricDescriptor;
 import io.opentelemetry.sdk.metrics.internal.state.DebugUtils;
+import io.opentelemetry.sdk.metrics.internal.view.ImmutableView;
 import io.opentelemetry.sdk.metrics.view.View;
 import org.junit.jupiter.api.Test;
 
 // Note: This class MUST be outside the io.opentelemetry.metrics package to work correctly.
-class TestSourceInfo {
+class SourceInfoTest {
   // Note: The line numbers for these statics are used as part of the test.
   private static final SourceInfo info = SourceInfo.fromCurrentStack();
 
   @Test
   void sourceInfoFindsStackTrace() {
-    assertThat(info.shortDebugString()).isEqualTo("TestSourceInfo.java:22");
+    assertThat(info.shortDebugString()).isEqualTo("SourceInfoTest.java:23");
     assertThat(info.multiLineDebugString())
         .startsWith(
-            "\tat io.opentelemetry.testing.TestSourceInfo.<clinit>(TestSourceInfo.java:22)\n");
+            "\tat io.opentelemetry.testing.SourceInfoTest.<clinit>(SourceInfoTest.java:23)\n");
   }
 
   @Test
@@ -83,7 +84,7 @@ class TestSourceInfo {
         .contains(simple.getSourceInstrument().getSourceInfo().multiLineDebugString())
         .contains("- Description [description2] does not match [description]")
         .contains("Conflicting view registered")
-        .contains(problemView.getSourceInfo().multiLineDebugString())
+        .contains(ImmutableView.getSourceInfo(problemView).multiLineDebugString())
         .contains("FROM instrument name")
         .contains(
             simpleWithNewDescription.getSourceInstrument().getSourceInfo().multiLineDebugString());
@@ -113,7 +114,7 @@ class TestSourceInfo {
     assertThat(DebugUtils.duplicateMetricErrorMessage(simple, simpleWithNewDescription))
         .contains("Found duplicate metric definition: name")
         .contains("VIEW defined")
-        .contains(problemView.getSourceInfo().multiLineDebugString())
+        .contains(ImmutableView.getSourceInfo(problemView).multiLineDebugString())
         .contains("FROM instrument name2")
         .contains(simple.getSourceInstrument().getSourceInfo().multiLineDebugString())
         .contains("- Unit [unit] does not match [unit2]")

sdk/metrics/src/main/java/io/opentelemetry/sdk/metrics/internal/state/AsynchronousMetricStorage.java

@@ -23,6 +23,7 @@ import io.opentelemetry.sdk.metrics.internal.descriptor.InstrumentDescriptor;
 import io.opentelemetry.sdk.metrics.internal.descriptor.MetricDescriptor;
 import io.opentelemetry.sdk.metrics.internal.export.CollectionInfo;
 import io.opentelemetry.sdk.metrics.internal.view.AttributesProcessor;
+import io.opentelemetry.sdk.metrics.internal.view.ImmutableView;
 import io.opentelemetry.sdk.metrics.view.View;
 import io.opentelemetry.sdk.resources.Resource;
 import java.util.HashMap;
@@ -74,7 +75,7 @@ public class AsynchronousMetricStorage<T, O> implements MetricStorage {
     AsyncAccumulator<T> accumulator = new AsyncAccumulator<>(instrument);
     ObservableDoubleMeasurement measurement =
         new ObservableDoubleMeasurementImpl<>(
-            aggregator, accumulator, view.getAttributesProcessor());
+            aggregator, accumulator, ImmutableView.getAttributesProcessor(view));
     return new AsynchronousMetricStorage<>(metricDescriptor, aggregator, accumulator, measurement);
   }
 
@@ -88,7 +89,8 @@ public class AsynchronousMetricStorage<T, O> implements MetricStorage {
             .createAggregator(instrument, ExemplarFilter.neverSample());
     AsyncAccumulator<T> accumulator = new AsyncAccumulator<>(instrument);
     ObservableLongMeasurement measurement =
-        new ObservableLongMeasurementImpl<>(aggregator, accumulator, view.getAttributesProcessor());
+        new ObservableLongMeasurementImpl<>(
+            aggregator, accumulator, ImmutableView.getAttributesProcessor(view));
     return new AsynchronousMetricStorage<>(metricDescriptor, aggregator, accumulator, measurement);
   }
 

sdk/metrics/src/main/java/io/opentelemetry/sdk/metrics/internal/state/DebugUtils.java

@@ -6,6 +6,7 @@
 package io.opentelemetry.sdk.metrics.internal.state;
 
 import io.opentelemetry.sdk.metrics.internal.descriptor.MetricDescriptor;
+import io.opentelemetry.sdk.metrics.internal.view.ImmutableView;
 
 /**
  * Utilities for logging metric diagnostic issues.
@@ -45,7 +46,7 @@ public final class DebugUtils {
       result.append("\tVIEW defined\n");
       conflict
           .getSourceView()
-          .ifPresent(v -> result.append(v.getSourceInfo().multiLineDebugString()));
+          .ifPresent(v -> result.append(ImmutableView.getSourceInfo(v).multiLineDebugString()));
       result
           .append("\tFROM instrument ")
           .append(conflict.getSourceInstrument().getName())
@@ -109,7 +110,8 @@ public final class DebugUtils {
       result.append("Conflicting view registered.\n");
       existing
           .getSourceView()
-          .ifPresent(view -> result.append(view.getSourceInfo().multiLineDebugString()));
+          .ifPresent(
+              view -> result.append(ImmutableView.getSourceInfo(view).multiLineDebugString()));
       result
           .append("FROM instrument ")
           .append(existing.getSourceInstrument().getName())

sdk/metrics/src/main/java/io/opentelemetry/sdk/metrics/internal/state/SynchronousMetricStorage.java

@@ -11,6 +11,7 @@ import io.opentelemetry.sdk.metrics.internal.aggregator.Aggregator;
 import io.opentelemetry.sdk.metrics.internal.aggregator.AggregatorFactory;
 import io.opentelemetry.sdk.metrics.internal.descriptor.InstrumentDescriptor;
 import io.opentelemetry.sdk.metrics.internal.descriptor.MetricDescriptor;
+import io.opentelemetry.sdk.metrics.internal.view.ImmutableView;
 import io.opentelemetry.sdk.metrics.view.View;
 
 /**
@@ -43,6 +44,6 @@ public interface SynchronousMetricStorage extends MetricStorage, WriteableMetric
       return empty();
     }
     return new DefaultSynchronousMetricStorage<>(
-        metricDescriptor, aggregator, view.getAttributesProcessor());
+        metricDescriptor, aggregator, ImmutableView.getAttributesProcessor(view));
   }
 }

sdk/metrics/src/main/java/io/opentelemetry/sdk/metrics/internal/view/ImmutableView.java

@@ -0,0 +1,56 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.sdk.metrics.internal.view;
+
+import com.google.auto.value.AutoValue;
+import io.opentelemetry.sdk.metrics.internal.debug.SourceInfo;
+import io.opentelemetry.sdk.metrics.view.Aggregation;
+import io.opentelemetry.sdk.metrics.view.View;
+import javax.annotation.Nullable;
+import javax.annotation.concurrent.Immutable;
+
+/**
+ * A configuration for a metric stream transformation.
+ *
+ * <p>This class is internal and is hence not for public use. Its APIs are unstable and can change
+ * at any time.
+ */
+@AutoValue
+@Immutable
+public abstract class ImmutableView implements View {
+
+  /** Returns the {@link AttributesProcessor} for the {@link View}. */
+  public static AttributesProcessor getAttributesProcessor(View view) {
+    if (view instanceof ImmutableView) {
+      return ((ImmutableView) view).getAttributesProcessor();
+    }
+    return AttributesProcessor.NOOP;
+  }
+
+  /** Processor of attributes before performing aggregation. */
+  abstract AttributesProcessor getAttributesProcessor();
+
+  /** Returns the {@link SourceInfo} for the {@link View}. */
+  public static SourceInfo getSourceInfo(View view) {
+    if (view instanceof ImmutableView) {
+      return ((ImmutableView) view).getSourceInfo();
+    }
+    return SourceInfo.noSourceInfo();
+  }
+
+  /** Information about where the View was defined. */
+  abstract SourceInfo getSourceInfo();
+
+  static ImmutableView create(
+      @Nullable String name,
+      @Nullable String description,
+      Aggregation aggregation,
+      AttributesProcessor attributesProcessor) {
+    // TODO - Add the ability to track when a View was registered via a config file.
+    return new AutoValue_ImmutableView(
+        name, description, aggregation, attributesProcessor, SourceInfo.fromCurrentStack());
+  }
+}

sdk/metrics/src/main/java/io/opentelemetry/sdk/metrics/internal/view/ViewBuilderImpl.java

@@ -0,0 +1,81 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.sdk.metrics.internal.view;
+
+import io.opentelemetry.sdk.metrics.view.Aggregation;
+import io.opentelemetry.sdk.metrics.view.View;
+import io.opentelemetry.sdk.metrics.view.ViewBuilder;
+import java.util.function.Predicate;
+import javax.annotation.Nullable;
+
+/**
+ * Builder of metric {@link View}s.
+ *
+ * <p>This class is internal and is hence not for public use. Its APIs are unstable and can change
+ * at any time.
+ */
+public final class ViewBuilderImpl implements ViewBuilder {
+  @Nullable private String name = null;
+  @Nullable private String description = null;
+  private Aggregation aggregation = Aggregation.defaultAggregation();
+  private AttributesProcessor processor = AttributesProcessor.noop();
+
+  public ViewBuilderImpl() {}
+
+  @Override
+  public ViewBuilder setName(String name) {
+    this.name = name;
+    return this;
+  }
+
+  @Override
+  public ViewBuilder setDescription(String description) {
+    this.description = description;
+    return this;
+  }
+
+  @Override
+  public ViewBuilder setAggregation(Aggregation aggregation) {
+    this.aggregation = aggregation;
+    return this;
+  }
+
+  @Override
+  public ViewBuilder setAttributeFilter(Predicate<String> keyFilter) {
+    this.processor = this.processor.then(AttributesProcessor.filterByKeyName(keyFilter));
+    return this;
+  }
+
+  /**
+   * Appends key-values from baggage to all measurements.
+   *
+   * <p>Note: This runs after all other attribute processing added so far.
+   *
+   * @param keyFilter Only baggage key values pairs where the key matches this predicate will be
+   *     appended.
+   * @return this Builder.
+   */
+  public ViewBuilder appendFilteredBaggageAttributes(Predicate<String> keyFilter) {
+    this.processor = this.processor.then(AttributesProcessor.appendBaggageByKeyName(keyFilter));
+    return this;
+  }
+
+  /**
+   * Appends all key-values from baggage to all measurements.
+   *
+   * <p>Note: This runs after all other attribute processing added so far.
+   *
+   * @return this Builder.
+   */
+  public ViewBuilder appendAllBaggageAttributes() {
+    return appendFilteredBaggageAttributes(StringPredicates.ALL);
+  }
+
+  @Override
+  public View build() {
+    return ImmutableView.create(this.name, this.description, this.aggregation, this.processor);
+  }
+}

sdk/metrics/src/main/java/io/opentelemetry/sdk/metrics/view/View.java

@@ -5,49 +5,28 @@
 
 package io.opentelemetry.sdk.metrics.view;
 
-import com.google.auto.value.AutoValue;
-import io.opentelemetry.sdk.metrics.internal.debug.SourceInfo;
-import io.opentelemetry.sdk.metrics.internal.view.AttributesProcessor;
+import io.opentelemetry.sdk.metrics.internal.view.ViewBuilderImpl;
 import javax.annotation.Nullable;
-import javax.annotation.concurrent.Immutable;
 
-/** TODO: javadoc. */
-@AutoValue
-@Immutable
-public abstract class View {
+/** A configuration for a metric stream transformation. */
+public interface View {
+  /** Returns a {@linkplain ViewBuilder builder} for a {@link View}. */
+  static ViewBuilder builder() {
+    return new ViewBuilderImpl();
+  }
 
   /**
    * The name of the resulting metric to generate, or {@code null} if the same as the instrument.
    */
   @Nullable
-  public abstract String getName();
+  String getName();
 
   /**
    * The name of the resulting metric to generate, or {@code null} if the same as the instrument.
    */
   @Nullable
-  public abstract String getDescription();
+  String getDescription();
 
   /** The aggregation used for this view. */
-  public abstract Aggregation getAggregation();
-
-  /** Processor of attributes before performing aggregation. */
-  public abstract AttributesProcessor getAttributesProcessor();
-
-  /** Information about where the View was defined. */
-  public abstract SourceInfo getSourceInfo();
-
-  public static ViewBuilder builder() {
-    return new ViewBuilder();
-  }
-
-  static View create(
-      @Nullable String name,
-      @Nullable String description,
-      Aggregation aggregation,
-      AttributesProcessor attributesProcessor) {
-    // TODO - Add the ability to track when a View was registered via a config file.
-    return new AutoValue_View(
-        name, description, aggregation, attributesProcessor, SourceInfo.fromCurrentStack());
-  }
+  Aggregation getAggregation();
 }

sdk/metrics/src/main/java/io/opentelemetry/sdk/metrics/view/ViewBuilder.java

@@ -5,19 +5,10 @@
 
 package io.opentelemetry.sdk.metrics.view;
 
-import io.opentelemetry.sdk.metrics.internal.view.AttributesProcessor;
-import io.opentelemetry.sdk.metrics.internal.view.StringPredicates;
 import java.util.function.Predicate;
-import javax.annotation.Nullable;
 
-/** Builder of metric {@link View}s. */
-public final class ViewBuilder {
-  @Nullable private String name = null;
-  @Nullable private String description = null;
-  private Aggregation aggregation = Aggregation.defaultAggregation();
-  private AttributesProcessor processor = AttributesProcessor.noop();
-
-  ViewBuilder() {}
+/** A builder for {@link View}. */
+public interface ViewBuilder {
 
   /**
    * sets the name of the resulting metric.
@@ -25,10 +16,7 @@ public final class ViewBuilder {
    * @param name metric name or {@code null} if the underlying instrument name should be used.
    * @return this Builder.
    */
-  public ViewBuilder setName(String name) {
-    this.name = name;
-    return this;
-  }
+  ViewBuilder setName(String name);
 
   /**
    * sets the name of the resulting metric.
@@ -37,10 +25,7 @@ public final class ViewBuilder {
    *     should be used.
    * @return this Builder.
    */
-  public ViewBuilder setDescription(String description) {
-    this.description = description;
-    return this;
-  }
+  ViewBuilder setDescription(String description);
 
   /**
    * sets {@link Aggregation}.
@@ -48,10 +33,7 @@ public final class ViewBuilder {
    * @param aggregation aggregation to use.
    * @return this Builder.
    */
-  public ViewBuilder setAggregation(Aggregation aggregation) {
-    this.aggregation = aggregation;
-    return this;
-  }
+  ViewBuilder setAggregation(Aggregation aggregation);
 
   /**
    * Sets a filter for attributes, where only attribute names that pass the supplied {@link
@@ -62,38 +44,8 @@ public final class ViewBuilder {
    * @param keyFilter filter for key names to include.
    * @return this Builder.
    */
-  public ViewBuilder setAttributeFilter(Predicate<String> keyFilter) {
-    this.processor = this.processor.then(AttributesProcessor.filterByKeyName(keyFilter));
-    return this;
-  }
+  ViewBuilder setAttributeFilter(Predicate<String> keyFilter);
 
-  /**
-   * Appends key-values from baggage to all measurements.
-   *
-   * <p>Note: This runs after all other attribute processing added so far.
-   *
-   * @param keyFilter Only baggage key values pairs where the key matches this predicate will be
-   *     appended.
-   * @return this Builder.
-   */
-  public ViewBuilder appendFilteredBaggageAttributes(Predicate<String> keyFilter) {
-    this.processor = this.processor.then(AttributesProcessor.appendBaggageByKeyName(keyFilter));
-    return this;
-  }
-
-  /**
-   * Appends all key-values from baggage to all measurements.
-   *
-   * <p>Note: This runs after all other attribute processing added so far.
-   *
-   * @return this Builder.
-   */
-  public ViewBuilder appendAllBaggageAttributes() {
-    return appendFilteredBaggageAttributes(StringPredicates.ALL);
-  }
-
-  /** Returns the resulting {@link View}. */
-  public View build() {
-    return View.create(this.name, this.description, this.aggregation, this.processor);
-  }
+  /** Returns a {@link View} with the configuration of this builder. */
+  View build();
 }

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

@@ -29,6 +29,7 @@ import io.opentelemetry.sdk.metrics.common.InstrumentType;
 import io.opentelemetry.sdk.metrics.data.LongPointData;
 import io.opentelemetry.sdk.metrics.data.MetricData;
 import io.opentelemetry.sdk.metrics.export.MetricReader;
+import io.opentelemetry.sdk.metrics.internal.view.ViewBuilderImpl;
 import io.opentelemetry.sdk.metrics.view.Aggregation;
 import io.opentelemetry.sdk.metrics.view.InstrumentSelector;
 import io.opentelemetry.sdk.metrics.view.View;
@@ -691,8 +692,7 @@ class SdkMeterProviderTest {
             .registerMetricReader(reader)
             .registerView(
                 selector,
-                View.builder()
-                    .setAggregation(Aggregation.sum())
+                ((ViewBuilderImpl) View.builder().setAggregation(Aggregation.sum()))
                     .appendAllBaggageAttributes()
                     .build())
             .build();