Move micrometer shim library instrumentation back (#6538)

* Move micrometer shim library instrumentation back

* Switch package to io.opentelemetry.instrumentation.micrometer.v1_5

* Change instrumentation name

instrumentation/micrometer/micrometer-1.5/library/build.gradle.kts

@@ -0,0 +1,9 @@
+plugins {
+  id("otel.library-instrumentation")
+}
+
+dependencies {
+  library("io.micrometer:micrometer-core:1.5.0")
+
+  testImplementation(project(":instrumentation:micrometer:micrometer-1.5:testing"))
+}

instrumentation/micrometer/micrometer-1.5/library/src/main/java/io/opentelemetry/instrumentation/micrometer/v1_5/Bridging.java

@@ -0,0 +1,63 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.instrumentation.micrometer.v1_5;
+
+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;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
+
+final class Bridging {
+
+  private static final ConcurrentMap<String, String> descriptionsCache = new ConcurrentHashMap<>();
+
+  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) {
+    return descriptionsCache.computeIfAbsent(
+        id.getName(),
+        n -> {
+          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() {}
+}

instrumentation/micrometer/micrometer-1.5/library/src/main/java/io/opentelemetry/instrumentation/micrometer/v1_5/DoubleMeasurementRecorder.java

@@ -0,0 +1,38 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.instrumentation.micrometer.v1_5;
+
+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);
+    }
+  }
+}

instrumentation/micrometer/micrometer-1.5/library/src/main/java/io/opentelemetry/instrumentation/micrometer/v1_5/LongMeasurementRecorder.java

@@ -0,0 +1,38 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.instrumentation.micrometer.v1_5;
+
+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);
+    }
+  }
+}

instrumentation/micrometer/micrometer-1.5/library/src/main/java/io/opentelemetry/instrumentation/micrometer/v1_5/OpenTelemetryCounter.java

@@ -0,0 +1,67 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.instrumentation.micrometer.v1_5;
+
+import static io.opentelemetry.instrumentation.micrometer.v1_5.Bridging.baseUnit;
+import static io.opentelemetry.instrumentation.micrometer.v1_5.Bridging.name;
+import static io.opentelemetry.instrumentation.micrometer.v1_5.Bridging.tagsAsAttributes;
+
+import io.micrometer.core.instrument.AbstractMeter;
+import io.micrometer.core.instrument.Counter;
+import io.micrometer.core.instrument.Measurement;
+import io.micrometer.core.instrument.config.NamingConvention;
+import io.opentelemetry.api.common.Attributes;
+import io.opentelemetry.api.metrics.DoubleCounter;
+import io.opentelemetry.api.metrics.Meter;
+import java.util.Collections;
+
+final class OpenTelemetryCounter extends AbstractMeter implements Counter, RemovableMeter {
+
+  // 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) {
+    super(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 void onRemove() {
+    removed = true;
+  }
+}

instrumentation/micrometer/micrometer-1.5/library/src/main/java/io/opentelemetry/instrumentation/micrometer/v1_5/OpenTelemetryDistributionSummary.java

@@ -0,0 +1,165 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.instrumentation.micrometer.v1_5;
+
+import static io.opentelemetry.instrumentation.micrometer.v1_5.Bridging.baseUnit;
+import static io.opentelemetry.instrumentation.micrometer.v1_5.Bridging.name;
+import static io.opentelemetry.instrumentation.micrometer.v1_5.Bridging.tagsAsAttributes;
+
+import io.micrometer.core.instrument.AbstractDistributionSummary;
+import io.micrometer.core.instrument.Clock;
+import io.micrometer.core.instrument.Measurement;
+import io.micrometer.core.instrument.config.NamingConvention;
+import io.micrometer.core.instrument.distribution.DistributionStatisticConfig;
+import io.micrometer.core.instrument.distribution.NoopHistogram;
+import io.micrometer.core.instrument.distribution.TimeWindowMax;
+import io.opentelemetry.api.common.Attributes;
+import io.opentelemetry.api.metrics.DoubleHistogram;
+import io.opentelemetry.api.metrics.Meter;
+import io.opentelemetry.api.metrics.ObservableDoubleGauge;
+import java.util.Collections;
+import java.util.concurrent.atomic.DoubleAdder;
+import java.util.concurrent.atomic.LongAdder;
+
+final class OpenTelemetryDistributionSummary extends AbstractDistributionSummary
+    implements RemovableMeter {
+
+  private final Measurements measurements;
+  private final TimeWindowMax max;
+  // TODO: use bound instruments when they're available
+  private final DoubleHistogram otelHistogram;
+  private final Attributes attributes;
+  private final ObservableDoubleGauge observableMax;
+
+  private volatile boolean removed = false;
+
+  OpenTelemetryDistributionSummary(
+      Id id,
+      NamingConvention namingConvention,
+      Clock clock,
+      DistributionStatisticConfig distributionStatisticConfig,
+      double scale,
+      Meter otelMeter) {
+    super(id, clock, distributionStatisticConfig, scale, false);
+
+    if (isUsingMicrometerHistograms()) {
+      measurements = new MicrometerHistogramMeasurements();
+    } else {
+      measurements = NoopMeasurements.INSTANCE;
+    }
+    max = new TimeWindowMax(clock, distributionStatisticConfig);
+
+    this.attributes = tagsAsAttributes(id, namingConvention);
+
+    String name = name(id, namingConvention);
+    this.otelHistogram =
+        otelMeter
+            .histogramBuilder(name)
+            .setDescription(Bridging.description(id))
+            .setUnit(baseUnit(id))
+            .build();
+    this.observableMax =
+        otelMeter
+            .gaugeBuilder(name + ".max")
+            .setDescription(Bridging.description(id))
+            .setUnit(baseUnit(id))
+            .buildWithCallback(
+                new DoubleMeasurementRecorder<>(max, TimeWindowMax::poll, attributes));
+  }
+
+  boolean isUsingMicrometerHistograms() {
+    return histogram != NoopHistogram.INSTANCE;
+  }
+
+  @Override
+  protected void recordNonNegative(double amount) {
+    if (!removed) {
+      otelHistogram.record(amount, attributes);
+      measurements.record(amount);
+      max.record(amount);
+    }
+  }
+
+  @Override
+  public long count() {
+    return measurements.count();
+  }
+
+  @Override
+  public double totalAmount() {
+    return measurements.totalAmount();
+  }
+
+  @Override
+  public double max() {
+    return max.poll();
+  }
+
+  @Override
+  public Iterable<Measurement> measure() {
+    UnsupportedReadLogger.logWarning();
+    return Collections.emptyList();
+  }
+
+  @Override
+  public void onRemove() {
+    removed = true;
+    observableMax.close();
+  }
+
+  private interface Measurements {
+    void record(double amount);
+
+    long count();
+
+    double totalAmount();
+  }
+
+  // if micrometer histograms are not being used then there's no need to keep any local state
+  // OpenTelemetry metrics bridge does not support reading measurements
+  enum NoopMeasurements implements Measurements {
+    INSTANCE;
+
+    @Override
+    public void record(double amount) {}
+
+    @Override
+    public long count() {
+      UnsupportedReadLogger.logWarning();
+      return 0;
+    }
+
+    @Override
+    public double totalAmount() {
+      UnsupportedReadLogger.logWarning();
+      return Double.NaN;
+    }
+  }
+
+  // calculate count and totalAmount value for the use of micrometer histograms
+  // kinda similar to how DropwizardDistributionSummary does that
+  private static final class MicrometerHistogramMeasurements implements Measurements {
+
+    private final LongAdder count = new LongAdder();
+    private final DoubleAdder totalAmount = new DoubleAdder();
+
+    @Override
+    public void record(double amount) {
+      count.increment();
+      totalAmount.add(amount);
+    }
+
+    @Override
+    public long count() {
+      return count.sum();
+    }
+
+    @Override
+    public double totalAmount() {
+      return totalAmount.sum();
+    }
+  }
+}