Stabilize MetricProducer, allow custom MetricReaders

docs/apidiffs/current_vs_latest/opentelemetry-sdk-metrics.txt

@@ -1,2 +1,12 @@
 Comparing source compatibility of  against 
-No changes.
+***  MODIFIED INTERFACE: PUBLIC ABSTRACT io.opentelemetry.sdk.metrics.export.CollectionRegistration  (not serializable)
+	===  CLASS FILE FORMAT VERSION: 52.0 <- 52.0
+	+++  NEW METHOD: PUBLIC(+) java.util.Collection<io.opentelemetry.sdk.metrics.data.MetricData> collectAllMetrics()
+	+++  NEW METHOD: PUBLIC(+) STATIC(+) io.opentelemetry.sdk.metrics.export.CollectionRegistration noop()
++++  NEW INTERFACE: PUBLIC(+) ABSTRACT(+) io.opentelemetry.sdk.metrics.export.MetricProducer  (not serializable)
+	+++  CLASS FILE FORMAT VERSION: 52.0 <- n.a.
+	+++  NEW SUPERCLASS: java.lang.Object
+	+++  NEW METHOD: PUBLIC(+) ABSTRACT(+) java.util.Collection<io.opentelemetry.sdk.metrics.data.MetricData> produce(io.opentelemetry.sdk.resources.Resource)
+***  MODIFIED CLASS: PUBLIC FINAL io.opentelemetry.sdk.metrics.SdkMeterProviderBuilder  (not serializable)
+	===  CLASS FILE FORMAT VERSION: 52.0 <- 52.0
+	+++  NEW METHOD: PUBLIC(+) io.opentelemetry.sdk.metrics.SdkMeterProviderBuilder registerMetricProducer(io.opentelemetry.sdk.metrics.export.MetricProducer)

exporters/prometheus/src/main/java/io/opentelemetry/exporter/prometheus/PrometheusHttpServer.java

@@ -22,7 +22,6 @@
 import io.opentelemetry.sdk.metrics.data.MetricData;
 import io.opentelemetry.sdk.metrics.export.CollectionRegistration;
 import io.opentelemetry.sdk.metrics.export.MetricReader;
-import io.opentelemetry.sdk.metrics.internal.export.MetricProducer;
 import java.io.IOException;
 import java.io.OutputStream;
 import java.io.UncheckedIOException;
@@ -60,7 +59,7 @@ public final class PrometheusHttpServer implements MetricReader {
 
   private final HttpServer server;
   private final ExecutorService executor;
-  private volatile MetricProducer metricProducer = MetricProducer.noop();
+  private volatile CollectionRegistration collectionRegistration = CollectionRegistration.noop();
 
   /**
    * Returns a new {@link PrometheusHttpServer} which can be registered to an {@link
@@ -83,7 +82,7 @@ public static PrometheusHttpServerBuilder builder() {
       throw new UncheckedIOException("Could not create Prometheus HTTP server", e);
     }
     MetricsHandler metricsHandler =
-        new MetricsHandler(() -> getMetricProducer().collectAllMetrics());
+        new MetricsHandler(() -> collectionRegistration.collectAllMetrics());
     server.createContext("/", metricsHandler);
     server.createContext("/metrics", metricsHandler);
     server.createContext("/-/healthy", HealthHandler.INSTANCE);
@@ -110,10 +109,6 @@ private static HttpServer createServer(String host, int port) throws IOException
     throw exception;
   }
 
-  private MetricProducer getMetricProducer() {
-    return metricProducer;
-  }
-
   private void start() {
     // server.start must be called from a daemon thread for it to be a daemon.
     if (Thread.currentThread().isDaemon()) {
@@ -131,13 +126,13 @@ private void start() {
   }
 
   @Override
-  public void register(CollectionRegistration registration) {
-    this.metricProducer = MetricProducer.asMetricProducer(registration);
+  public AggregationTemporality getAggregationTemporality(InstrumentType instrumentType) {
+    return AggregationTemporality.CUMULATIVE;
   }
 
   @Override
-  public AggregationTemporality getAggregationTemporality(InstrumentType instrumentType) {
-    return AggregationTemporality.CUMULATIVE;
+  public void register(CollectionRegistration registration) {
+    this.collectionRegistration = registration;
   }
 
   @Override

exporters/prometheus/src/test/java/io/opentelemetry/exporter/prometheus/PrometheusHttpServerTest.java

@@ -26,17 +26,18 @@
 import io.opentelemetry.sdk.common.InstrumentationScopeInfo;
 import io.opentelemetry.sdk.metrics.data.AggregationTemporality;
 import io.opentelemetry.sdk.metrics.data.MetricData;
+import io.opentelemetry.sdk.metrics.export.CollectionRegistration;
 import io.opentelemetry.sdk.metrics.internal.data.ImmutableDoublePointData;
 import io.opentelemetry.sdk.metrics.internal.data.ImmutableGaugeData;
 import io.opentelemetry.sdk.metrics.internal.data.ImmutableLongPointData;
 import io.opentelemetry.sdk.metrics.internal.data.ImmutableMetricData;
 import io.opentelemetry.sdk.metrics.internal.data.ImmutableSumData;
-import io.opentelemetry.sdk.metrics.internal.export.MetricProducer;
 import io.opentelemetry.sdk.resources.Resource;
 import java.io.ByteArrayInputStream;
 import java.io.IOException;
 import java.net.ServerSocket;
 import java.nio.charset.StandardCharsets;
+import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
 import java.util.concurrent.Executors;
@@ -56,7 +57,6 @@
 
 class PrometheusHttpServerTest {
   private static final AtomicReference<List<MetricData>> metricData = new AtomicReference<>();
-  private static final MetricProducer metricProducer = metricData::get;
 
   static PrometheusHttpServer prometheusServer;
   static WebClient client;
@@ -68,7 +68,13 @@ class PrometheusHttpServerTest {
   static void beforeAll() {
     // Register the SDK metric producer with the prometheus reader.
     prometheusServer = PrometheusHttpServer.builder().setHost("localhost").setPort(0).build();
-    prometheusServer.register(metricProducer);
+    prometheusServer.register(
+        new CollectionRegistration() {
+          @Override
+          public Collection<MetricData> collectAllMetrics() {
+            return metricData.get();
+          }
+        });
 
     client =
         WebClient.builder("http://localhost:" + prometheusServer.getAddress().getPort())

opencensus-shim/src/main/java/io/opentelemetry/opencensusshim/OpenCensusMetricProducer.java

@@ -0,0 +1,53 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.opencensusshim;
+
+import io.opencensus.metrics.Metrics;
+import io.opencensus.metrics.export.MetricProducerManager;
+import io.opentelemetry.opencensusshim.internal.metrics.MetricAdapter;
+import io.opentelemetry.sdk.metrics.SdkMeterProviderBuilder;
+import io.opentelemetry.sdk.metrics.data.MetricData;
+import io.opentelemetry.sdk.metrics.export.MetricProducer;
+import io.opentelemetry.sdk.metrics.export.MetricReader;
+import io.opentelemetry.sdk.resources.Resource;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+
+/**
+ * {@link MetricProducer} for OpenCensus metrics, which allows {@link MetricReader}s to read from
+ * both OpenTelemetry and OpenCensus metrics.
+ *
+ * <p>To use, register with {@link SdkMeterProviderBuilder#registerMetricProducer(MetricProducer)}.
+ */
+public final class OpenCensusMetricProducer implements MetricProducer {
+  private final MetricProducerManager openCensusMetricStorage;
+
+  OpenCensusMetricProducer(MetricProducerManager openCensusMetricStorage) {
+    this.openCensusMetricStorage = openCensusMetricStorage;
+  }
+
+  /**
+   * Constructs a new {@link OpenCensusMetricProducer} that reports against the given {@link
+   * Resource}.
+   */
+  public static MetricProducer create() {
+    return new OpenCensusMetricProducer(Metrics.getExportComponent().getMetricProducerManager());
+  }
+
+  @Override
+  public Collection<MetricData> produce(Resource resource) {
+    List<MetricData> result = new ArrayList<>();
+    openCensusMetricStorage
+        .getAllMetricProducer()
+        .forEach(
+            producer ->
+                producer
+                    .getMetrics()
+                    .forEach(metric -> result.add(MetricAdapter.convert(resource, metric))));
+    return result;
+  }
+}

opencensus-shim/src/test/java/io/opentelemetry/opencensusshim/metrics/OpenCensusMetricProducerTest.java

@@ -21,7 +21,8 @@
 import io.opencensus.trace.TraceOptions;
 import io.opencensus.trace.Tracestate;
 import io.opentelemetry.api.common.Attributes;
-import io.opentelemetry.sdk.metrics.internal.export.MetricProducer;
+import io.opentelemetry.opencensusshim.OpenCensusMetricProducer;
+import io.opentelemetry.sdk.metrics.export.MetricProducer;
 import io.opentelemetry.sdk.resources.Resource;
 import java.time.Duration;
 import java.util.Arrays;
@@ -31,8 +32,7 @@
 import org.junit.jupiter.api.Test;
 
 class OpenCensusMetricProducerTest {
-  private final MetricProducer openCensusMetrics =
-      OpenCensusMetricProducer.create(Resource.empty());
+  private final MetricProducer openCensusMetrics = OpenCensusMetricProducer.create();
 
   private static final Measure.MeasureLong LATENCY_MS =
       Measure.MeasureLong.create("task_latency", "The task latency in milliseconds", "ms");
@@ -69,7 +69,7 @@ void extractHistogram() throws InterruptedException {
         .atMost(Duration.ofSeconds(10))
         .untilAsserted(
             () ->
-                assertThat(openCensusMetrics.collectAllMetrics())
+                assertThat(openCensusMetrics.produce(Resource.empty()))
                     .satisfiesExactly(
                         metric ->
                             assertThat(metric)

opencensus-shim/src/test/java/io/opentelemetry/opencensusshim/metrics/OpenCensusMetricsTest.java

@@ -12,6 +12,7 @@
 import io.opencensus.stats.Stats;
 import io.opencensus.stats.StatsRecorder;
 import io.opencensus.stats.View;
+import io.opentelemetry.opencensusshim.OpenCensusMetricProducer;
 import io.opentelemetry.sdk.metrics.SdkMeterProvider;
 import io.opentelemetry.sdk.testing.exporter.InMemoryMetricReader;
 import java.time.Duration;
@@ -26,7 +27,10 @@ class OpenCensusMetricsTest {
   void capturesOpenCensusAndOtelMetrics() throws InterruptedException {
     InMemoryMetricReader reader = InMemoryMetricReader.create();
     SdkMeterProvider otelMetrics =
-        SdkMeterProvider.builder().registerMetricReader(OpenCensusMetrics.attachTo(reader)).build();
+        SdkMeterProvider.builder()
+            .registerMetricReader(reader)
+            .registerMetricProducer(OpenCensusMetricProducer.create())
+            .build();
     // Record an otel metric.
     otelMetrics.meterBuilder("otel").build().counterBuilder("otel.sum").build().add(1);
     // Record an OpenCensus metric.
@@ -47,7 +51,7 @@ void capturesOpenCensusAndOtelMetrics() throws InterruptedException {
         .untilAsserted(
             () ->
                 assertThat(reader.collectAllMetrics())
-                    .satisfiesExactly(
+                    .satisfiesExactlyInAnyOrder(
                         metric ->
                             assertThat(metric).hasName("otel.sum").hasLongSumSatisfying(sum -> {}),
                         metric ->

sdk/all/src/test/java/io/opentelemetry/sdk/OpenTelemetrySdkTest.java

@@ -421,6 +421,7 @@ void stringRepresentation() {
                 + "clock=SystemClock{}, "
                 + "resource=Resource{schemaUrl=null, attributes={service.name=\"otel-test\"}}, "
                 + "metricReaders=[PeriodicMetricReader{exporter=MockMetricExporter{}, intervalNanos=60000000000}], "
+                + "metricProducers=[], "
                 + "views=[RegisteredView{instrumentSelector=InstrumentSelector{instrumentName=instrument}, view=View{name=new-instrument, aggregation=DefaultAggregation, attributesProcessor=NoopAttributesProcessor{}, cardinalityLimit=2000}}]"
                 + "}, "
                 + "loggerProvider=SdkLoggerProvider{"