Add Metric Instrument Registry (#11103)

* added metric instrument registry

api/src/main/java/io/grpc/DoubleCounterMetricInstrument.java

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+/*
+ * Copyright 2024 The gRPC Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.grpc;
+
+import java.util.List;
+
+/**
+ * Represents a double-valued counter metric instrument.
+ */
+@Internal
+public final class DoubleCounterMetricInstrument extends PartialMetricInstrument {
+  DoubleCounterMetricInstrument(long index, String name, String description, String unit,
+      List<String> requiredLabelKeys, List<String> optionalLabelKeys, boolean enableByDefault) {
+    super(index, name, description, unit, requiredLabelKeys, optionalLabelKeys, enableByDefault);
+  }
+}

api/src/main/java/io/grpc/DoubleHistogramMetricInstrument.java

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+/*
+ * Copyright 2024 The gRPC Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.grpc;
+
+import java.util.List;
+
+/**
+ * Represents a double-valued histogram metric instrument.
+ */
+@Internal
+public final class DoubleHistogramMetricInstrument extends PartialMetricInstrument {
+  private final List<Double> bucketBoundaries;
+
+  DoubleHistogramMetricInstrument(long index, String name, String description, String unit,
+      List<Double> bucketBoundaries, List<String> requiredLabelKeys, List<String> optionalLabelKeys,
+      boolean enableByDefault) {
+    super(index, name, description, unit, requiredLabelKeys, optionalLabelKeys, enableByDefault);
+    this.bucketBoundaries = bucketBoundaries;
+  }
+
+  public List<Double> getBucketBoundaries() {
+    return bucketBoundaries;
+  }
+}

api/src/main/java/io/grpc/LongCounterMetricInstrument.java

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+/*
+ * Copyright 2024 The gRPC Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.grpc;
+
+import java.util.List;
+
+/**
+ * Represents a long-valued counter metric instrument.
+ */
+@Internal
+public final class LongCounterMetricInstrument extends PartialMetricInstrument {
+  LongCounterMetricInstrument(long index, String name, String description, String unit,
+      List<String> requiredLabelKeys, List<String> optionalLabelKeys, boolean enableByDefault) {
+    super(index, name, description, unit, requiredLabelKeys, optionalLabelKeys, enableByDefault);
+  }
+}

api/src/main/java/io/grpc/LongGaugeMetricInstrument.java

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+/*
+ * Copyright 2024 The gRPC Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.grpc;
+
+import java.util.List;
+
+/**
+ * Represents a long-valued gauge metric instrument.
+ */
+@Internal
+public final class LongGaugeMetricInstrument extends PartialMetricInstrument {
+  LongGaugeMetricInstrument(long index, String name, String description, String unit,
+      List<String> requiredLabelKeys, List<String> optionalLabelKeys, boolean enableByDefault) {
+    super(index, name, description, unit, requiredLabelKeys, optionalLabelKeys, enableByDefault);
+  }
+}

api/src/main/java/io/grpc/LongHistogramMetricInstrument.java

@@ -0,0 +1,38 @@
+/*
+ * Copyright 2024 The gRPC Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.grpc;
+
+import java.util.List;
+
+/**
+ * Represents a long-valued histogram metric instrument.
+ */
+@Internal
+public final class LongHistogramMetricInstrument extends PartialMetricInstrument {
+  private final List<Long> bucketBoundaries;
+
+  LongHistogramMetricInstrument(long index, String name, String description, String unit,
+      List<Long> bucketBoundaries, List<String> requiredLabelKeys, List<String> optionalLabelKeys,
+      boolean enableByDefault) {
+    super(index, name, description, unit, requiredLabelKeys, optionalLabelKeys, enableByDefault);
+    this.bucketBoundaries = bucketBoundaries;
+  }
+
+  public List<Long> getBucketBoundaries() {
+    return bucketBoundaries;
+  }
+}

api/src/main/java/io/grpc/MetricInstrument.java

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+/*
+ * Copyright 2024 The gRPC Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.grpc;
+
+import java.util.List;
+
+/**
+ * Represents a metric instrument. Metric instrument contains information used to describe a metric.
+ */
+@Internal
+public interface MetricInstrument {
+  /**
+   * Returns the unique index of this metric instrument.
+   *
+   * @return the index of the metric instrument.
+   */
+  public long getIndex();
+
+  /**
+   * Returns the name of the metric.
+   *
+   * @return the name of the metric.
+   */
+  public String getName();
+
+  /**
+   * Returns a description of the metric.
+   *
+   * @return a description of the metric.
+   */
+  public String getDescription();
+
+  /**
+   * Returns the unit of measurement for the metric.
+   *
+   * @return the unit of measurement.
+   */
+  public String getUnit();
+
+  /**
+   * Returns a list of required label keys for this metric instrument.
+   *
+   * @return a list of required label keys.
+   */
+  public List<String> getRequiredLabelKeys();
+
+  /**
+   * Returns a list of optional label keys for this metric instrument.
+   *
+   * @return a list of optional label keys.
+   */
+  public List<String> getOptionalLabelKeys();
+
+  /**
+   * Indicates whether this metric instrument is enabled by default.
+   *
+   * @return {@code true} if this metric instrument is enabled by default,
+   *         {@code false} otherwise.
+   */
+  public boolean isEnableByDefault();
+}