Bring in micrometer shim (#4258)

* Move in micrometer-shim

* Finish

* micrometer1

* Tweak

* micrometer1 module

* Fix build file

* Merge

dependencyManagement/build.gradle.kts

@@ -18,6 +18,7 @@ val DEPENDENCY_BOMS = listOf(
   "com.linecorp.armeria:armeria-bom:1.14.0",
   "com.squareup.okhttp3:okhttp-bom:4.9.3",
   "io.grpc:grpc-bom:1.44.0",
+  "io.micrometer:micrometer-bom:1.8.3",
   "io.zipkin.brave:brave-bom:5.13.7",
   "io.zipkin.reporter2:zipkin-reporter-bom:2.16.3",
   "org.junit:junit-bom:5.8.2",

micrometer1-shim/build.gradle.kts

@@ -0,0 +1,54 @@
+plugins {
+  id("otel.java-conventions")
+  id("otel.publish-conventions")
+}
+
+description = "OpenTelemetry Micrometer Bridge"
+otelJava.moduleName.set("io.opentelemetry.micrometer1shim")
+
+dependencies {
+  api(project(":api:all"))
+
+  api("io.micrometer:micrometer-core")
+
+  testImplementation(project(":sdk:metrics-testing"))
+  testImplementation(project(":sdk:testing"))
+}
+
+testing {
+  suites {
+    // Test older LTS versions
+    val testMicrometer15 by registering(JvmTestSuite::class) {
+      sources {
+        java {
+          setSrcDirs(listOf("src/test/java"))
+        }
+      }
+      dependencies {
+        implementation(project(":sdk:metrics-testing"))
+        implementation(project(":sdk:testing"))
+
+        implementation(project.dependencies.enforcedPlatform("io.micrometer:micrometer-bom:1.5.17"))
+      }
+    }
+    val testMicrometer16 by registering(JvmTestSuite::class) {
+      sources {
+        java {
+          setSrcDirs(listOf("src/test/java"))
+        }
+      }
+      dependencies {
+        implementation(project(":sdk:metrics-testing"))
+        implementation(project(":sdk:testing"))
+
+        implementation(project.dependencies.enforcedPlatform("io.micrometer:micrometer-bom:1.6.13"))
+      }
+    }
+  }
+}
+
+tasks {
+  check {
+    dependsOn(testing.suites)
+  }
+}

micrometer1-shim/gradle.properties

@@ -0,0 +1 @@
+otel.release=alpha

micrometer1-shim/src/main/java/io/opentelemetry/micrometer1shim/Bridging.java

@@ -0,0 +1,55 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.micrometer1shim;
+
+import io.micrometer.core.instrument.Meter;
+import io.micrometer.core.instrument.Statistic;
+import io.micrometer.core.instrument.Tag;
+import io.micrometer.core.instrument.config.NamingConvention;
+import io.opentelemetry.api.common.Attributes;
+import io.opentelemetry.api.common.AttributesBuilder;
+
+final class Bridging {
+
+  static Attributes tagsAsAttributes(Meter.Id id, NamingConvention namingConvention) {
+    Iterable<Tag> tags = id.getTagsAsIterable();
+    if (!tags.iterator().hasNext()) {
+      return Attributes.empty();
+    }
+    AttributesBuilder builder = Attributes.builder();
+    for (Tag tag : tags) {
+      String tagKey = namingConvention.tagKey(tag.getKey());
+      String tagValue = namingConvention.tagValue(tag.getValue());
+      builder.put(tagKey, tagValue);
+    }
+    return builder.build();
+  }
+
+  static String name(Meter.Id id, NamingConvention namingConvention) {
+    return namingConvention.name(id.getName(), id.getType(), id.getBaseUnit());
+  }
+
+  static String description(Meter.Id id) {
+    String description = id.getDescription();
+    return description != null ? description : "";
+  }
+
+  static String baseUnit(Meter.Id id) {
+    String baseUnit = id.getBaseUnit();
+    return baseUnit == null ? "1" : baseUnit;
+  }
+
+  static String statisticInstrumentName(
+      Meter.Id id, Statistic statistic, NamingConvention namingConvention) {
+    String prefix = id.getName() + ".";
+    // use "total_time" instead of "total" to avoid clashing with Statistic.TOTAL
+    String statisticStr =
+        statistic == Statistic.TOTAL_TIME ? "total_time" : statistic.getTagValueRepresentation();
+    return namingConvention.name(prefix + statisticStr, id.getType(), id.getBaseUnit());
+  }
+
+  private Bridging() {}
+}

micrometer1-shim/src/main/java/io/opentelemetry/micrometer1shim/DoubleMeasurementRecorder.java

@@ -0,0 +1,38 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.micrometer1shim;
+
+import io.opentelemetry.api.common.Attributes;
+import io.opentelemetry.api.metrics.ObservableDoubleMeasurement;
+import java.lang.ref.WeakReference;
+import java.util.function.Consumer;
+import java.util.function.ToDoubleFunction;
+import javax.annotation.Nullable;
+
+final class DoubleMeasurementRecorder<T> implements Consumer<ObservableDoubleMeasurement> {
+
+  // using a weak reference here so that the existence of the micrometer Meter does not block the
+  // measured object from being GC'd; e.g. a Gauge (or any other async instrument) must not block
+  // garbage collection of the object that it measures
+  private final WeakReference<T> objWeakRef;
+  private final ToDoubleFunction<T> metricFunction;
+  private final Attributes attributes;
+
+  DoubleMeasurementRecorder(
+      @Nullable T obj, ToDoubleFunction<T> metricFunction, Attributes attributes) {
+    this.objWeakRef = new WeakReference<>(obj);
+    this.metricFunction = metricFunction;
+    this.attributes = attributes;
+  }
+
+  @Override
+  public void accept(ObservableDoubleMeasurement measurement) {
+    T obj = objWeakRef.get();
+    if (obj != null) {
+      measurement.record(metricFunction.applyAsDouble(obj), attributes);
+    }
+  }
+}

micrometer1-shim/src/main/java/io/opentelemetry/micrometer1shim/LongMeasurementRecorder.java

@@ -0,0 +1,38 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.micrometer1shim;
+
+import io.opentelemetry.api.common.Attributes;
+import io.opentelemetry.api.metrics.ObservableLongMeasurement;
+import java.lang.ref.WeakReference;
+import java.util.function.Consumer;
+import java.util.function.ToLongFunction;
+import javax.annotation.Nullable;
+
+final class LongMeasurementRecorder<T> implements Consumer<ObservableLongMeasurement> {
+
+  // using a weak reference here so that the existence of the micrometer Meter does not block the
+  // measured object from being GC'd; e.g. a Gauge (or any other async instrument) must not block
+  // garbage collection of the object that it measures
+  private final WeakReference<T> objWeakRef;
+  private final ToLongFunction<T> metricFunction;
+  private final Attributes attributes;
+
+  LongMeasurementRecorder(
+      @Nullable T obj, ToLongFunction<T> metricFunction, Attributes attributes) {
+    this.objWeakRef = new WeakReference<>(obj);
+    this.metricFunction = metricFunction;
+    this.attributes = attributes;
+  }
+
+  @Override
+  public void accept(ObservableLongMeasurement measurement) {
+    T obj = objWeakRef.get();
+    if (obj != null) {
+      measurement.record(metricFunction.applyAsLong(obj), attributes);
+    }
+  }
+}

micrometer1-shim/src/main/java/io/opentelemetry/micrometer1shim/OpenTelemetryCounter.java

@@ -0,0 +1,86 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.micrometer1shim;
+
+import static io.opentelemetry.micrometer1shim.Bridging.baseUnit;
+import static io.opentelemetry.micrometer1shim.Bridging.name;
+import static io.opentelemetry.micrometer1shim.Bridging.tagsAsAttributes;
+
+import io.micrometer.core.instrument.Counter;
+import io.micrometer.core.instrument.Measurement;
+import io.micrometer.core.instrument.config.NamingConvention;
+import io.micrometer.core.instrument.util.MeterEquivalence;
+import io.opentelemetry.api.common.Attributes;
+import io.opentelemetry.api.metrics.DoubleCounter;
+import io.opentelemetry.api.metrics.Meter;
+import java.util.Collections;
+import javax.annotation.Nullable;
+
+@SuppressWarnings("HashCodeToString")
+final class OpenTelemetryCounter implements Counter, RemovableMeter {
+
+  private final Id id;
+  // TODO: use bound instruments when they're available
+  private final DoubleCounter otelCounter;
+  private final Attributes attributes;
+
+  private volatile boolean removed = false;
+
+  OpenTelemetryCounter(Id id, NamingConvention namingConvention, Meter otelMeter) {
+    this.id = id;
+
+    this.attributes = tagsAsAttributes(id, namingConvention);
+    String conventionName = name(id, namingConvention);
+    this.otelCounter =
+        otelMeter
+            .counterBuilder(conventionName)
+            .setDescription(Bridging.description(id))
+            .setUnit(baseUnit(id))
+            .ofDoubles()
+            .build();
+  }
+
+  @Override
+  public void increment(double v) {
+    if (removed) {
+      return;
+    }
+    otelCounter.add(v, attributes);
+  }
+
+  @Override
+  public double count() {
+    UnsupportedReadLogger.logWarning();
+    return Double.NaN;
+  }
+
+  @Override
+  public Iterable<Measurement> measure() {
+    UnsupportedReadLogger.logWarning();
+    return Collections.emptyList();
+  }
+
+  @Override
+  public Id getId() {
+    return id;
+  }
+
+  @Override
+  public void onRemove() {
+    removed = true;
+  }
+
+  @SuppressWarnings("EqualsWhichDoesntCheckParameterClass")
+  @Override
+  public boolean equals(@Nullable Object o) {
+    return MeterEquivalence.equals(this, o);
+  }
+
+  @Override
+  public int hashCode() {
+    return MeterEquivalence.hashCode(this);
+  }
+}