Metrics SDK odds and ends (#4273)

* Metrics SDK odds and ends

* Make InstrumentSelectorBuilder contructor package private

* Fix build

* Improve documentation for SdkMeterProviderBuilder defaults

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

@@ -61,10 +61,10 @@ public final class SdkMeterProvider implements MeterProvider, Closeable {
       Clock clock,
       Resource resource,
       ViewRegistry viewRegistry,
-      ExemplarFilter exemplarSampler,
+      ExemplarFilter exemplarFilter,
       long minimumCollectionIntervalNanos) {
     this.sharedState =
-        MeterProviderSharedState.create(clock, resource, viewRegistry, exemplarSampler);
+        MeterProviderSharedState.create(clock, resource, viewRegistry, exemplarFilter);
     this.registry =
         new ComponentRegistry<>(
             instrumentationLibraryInfo -> new SdkMeter(sharedState, instrumentationLibraryInfo));

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

@@ -25,13 +25,27 @@ import java.util.concurrent.TimeUnit;
 /** Builder class for the {@link SdkMeterProvider}. */
 public final class SdkMeterProviderBuilder {
 
+  /**
+   * By default, the exemplar filter is set to sample with traces.
+   *
+   * @see #setExemplarFilter(ExemplarFilter)
+   */
+  private static final ExemplarFilter DEFAULT_EXEMPLAR_FILTER = ExemplarFilter.sampleWithTraces();
+
+  /**
+   * By default, the minimum collection interval is 100ns.
+   *
+   * @see #setMinimumCollectionInterval(Duration)
+   */
+  private static final long DEFAULT_MIN_COLLECTION_INTERVAL_NANOS =
+      TimeUnit.MILLISECONDS.toNanos(100);
+
   private Clock clock = Clock.getDefault();
   private Resource resource = Resource.getDefault();
   private final ViewRegistryBuilder viewRegistryBuilder = ViewRegistry.builder();
   private final List<MetricReaderFactory> metricReaders = new ArrayList<>();
-  // Default the sampling strategy.
-  private ExemplarFilter exemplarFilter = ExemplarFilter.sampleWithTraces();
-  private long minimumCollectionIntervalNanos = TimeUnit.MILLISECONDS.toNanos(100);
+  private ExemplarFilter exemplarFilter = DEFAULT_EXEMPLAR_FILTER;
+  private long minimumCollectionIntervalNanos = DEFAULT_MIN_COLLECTION_INTERVAL_NANOS;
 
   SdkMeterProviderBuilder() {}
 

sdk/metrics/src/main/java/io/opentelemetry/sdk/metrics/data/ExemplarData.java

@@ -20,7 +20,7 @@ public interface ExemplarData {
   /**
    * The set of key/value pairs that were filtered out by the aggregator, but recorded alongside the
    * original measurement. Only key/value pairs that were filtered out by the aggregator should be
-   * included
+   * included.
    */
   Attributes getFilteredAttributes();
 

sdk/metrics/src/main/java/io/opentelemetry/sdk/metrics/exemplar/FixedSizeExemplarReservoir.java

@@ -16,7 +16,7 @@ import java.util.function.Supplier;
 /**
  * A Reservoir sampler with fixed size that stores the given number of exemplars.
  *
- * <p>This implementation uses a un-unweighted/naive algorithm for sampler where the probability of
+ * <p>This implementation uses an un-unweighted/naive algorithm for sampler where the probability of
  * sampling decrease as the number of observations continue. The collectAndReset method resets the
  * count of observations, making the probability of sampling effectively 1.0.
  *
@@ -33,7 +33,7 @@ final class FixedSizeExemplarReservoir extends AbstractFixedSizeExemplarReservoi
    * @param size The number of exemplars to preserve.
    * @param randomSupplier The random number generator to use for sampling.
    */
-  public FixedSizeExemplarReservoir(Clock clock, int size, Supplier<Random> randomSupplier) {
+  FixedSizeExemplarReservoir(Clock clock, int size, Supplier<Random> randomSupplier) {
     super(clock, size);
     this.randomSupplier = randomSupplier;
   }

sdk/metrics/src/main/java/io/opentelemetry/sdk/metrics/internal/descriptor/InstrumentDescriptor.java

@@ -33,6 +33,8 @@ public abstract class InstrumentDescriptor {
     return new AutoValue_InstrumentDescriptor(name, description, unit, type, valueType);
   }
 
+  InstrumentDescriptor() {}
+
   public abstract String getName();
 
   public abstract String getDescription();

sdk/metrics/src/main/java/io/opentelemetry/sdk/metrics/internal/descriptor/MetricDescriptor.java

@@ -48,6 +48,8 @@ public abstract class MetricDescriptor {
     return new AutoValue_MetricDescriptor(name, description, view, instrument);
   }
 
+  MetricDescriptor() {}
+
   /**
    * The name of the descriptor, equal to {@link View#getName()} if not null, else {@link
    * InstrumentDescriptor#getName()}.

sdk/metrics/src/main/java/io/opentelemetry/sdk/metrics/internal/export/CollectionInfo.java

@@ -21,6 +21,15 @@ import javax.annotation.concurrent.Immutable;
 @AutoValue
 @Immutable
 public abstract class CollectionInfo {
+
+  /** Construct a new collection info object storing information for collection against a reader. */
+  public static CollectionInfo create(
+      CollectionHandle handle, Set<CollectionHandle> allCollectors, MetricReader reader) {
+    return new AutoValue_CollectionInfo(handle, allCollectors, reader);
+  }
+
+  CollectionInfo() {}
+
   /** The current collection. */
   public abstract CollectionHandle getCollector();
   /** The set of all possible collectors. */
@@ -33,10 +42,4 @@ public abstract class CollectionInfo {
   public final AggregationTemporality getPreferredAggregation() {
     return getReader().getPreferredTemporality();
   }
-
-  /** Construct a new collection info object storing information for collection against a reader. */
-  public static CollectionInfo create(
-      CollectionHandle handle, Set<CollectionHandle> allCollectors, MetricReader reader) {
-    return new AutoValue_CollectionInfo(handle, allCollectors, reader);
-  }
 }

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

@@ -27,6 +27,8 @@ public abstract class MeterProviderSharedState {
         clock, resource, viewRegistry, clock.now(), exemplarFilter);
   }
 
+  MeterProviderSharedState() {}
+
   /** Returns the clock used for measurements. */
   public abstract Clock getClock();
 

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

@@ -34,6 +34,8 @@ public abstract class MeterSharedState {
     return new AutoValue_MeterSharedState(instrumentationScopeInfo, new MetricStorageRegistry());
   }
 
+  MeterSharedState() {}
+
   // only visible for testing.
   /** Returns the {@link InstrumentationScopeInfo} for this {@code Meter}. */
   public abstract InstrumentationScopeInfo getInstrumentationScopeInfo();

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

@@ -22,6 +22,8 @@ import javax.annotation.concurrent.Immutable;
 @Immutable
 public abstract class ImmutableView implements View {
 
+  ImmutableView() {}
+
   /** Returns the {@link AttributesProcessor} for the {@link View}. */
   public static AttributesProcessor getAttributesProcessor(View view) {
     if (view instanceof ImmutableView) {

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

@@ -19,12 +19,15 @@ import javax.annotation.concurrent.Immutable;
 @AutoValue
 @Immutable
 abstract class RegisteredView {
-  /** Instrument fitler for applying this view. */
-  abstract InstrumentSelector getInstrumentSelector();
-  /** The view to apply. */
-  abstract View getView();
 
   static RegisteredView create(InstrumentSelector selector, View view) {
     return new AutoValue_RegisteredView(selector, view);
   }
+
+  RegisteredView() {}
+
+  /** Instrument fitler for applying this view. */
+  abstract InstrumentSelector getInstrumentSelector();
+  /** The view to apply. */
+  abstract View getView();
 }

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

@@ -38,6 +38,8 @@ public abstract class InstrumentSelector {
         meterSchemaUrlFilter);
   }
 
+  InstrumentSelector() {}
+
   /**
    * Returns {@link InstrumentType} that should be selected. If null, then this specifier will not
    * be used.

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

@@ -22,6 +22,8 @@ public final class InstrumentSelectorBuilder {
   private Predicate<String> meterVersionFilter = StringPredicates.ALL;
   private Predicate<String> meterSchemaUrlFilter = StringPredicates.ALL;
 
+  InstrumentSelectorBuilder() {}
+
   /** Sets a specifier for {@link InstrumentType}. */
   public InstrumentSelectorBuilder setType(InstrumentType instrumentType) {
     requireNonNull(instrumentType, "instrumentType");

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

@@ -11,7 +11,7 @@ import java.util.function.Predicate;
 public interface ViewBuilder {
 
   /**
-   * sets the name of the resulting metric.
+   * Sets the name of the resulting metric.
    *
    * @param name metric name or {@code null} if the underlying instrument name should be used.
    * @return this Builder.
@@ -19,7 +19,7 @@ public interface ViewBuilder {
   ViewBuilder setName(String name);
 
   /**
-   * sets the name of the resulting metric.
+   * Sets the description of the resulting metric.
    *
    * @param description metric description or {@code null} if the underlying instrument description
    *     should be used.
@@ -28,7 +28,7 @@ public interface ViewBuilder {
   ViewBuilder setDescription(String description);
 
   /**
-   * sets {@link Aggregation}.
+   * Sets {@link Aggregation}.
    *
    * @param aggregation aggregation to use.
    * @return this Builder.