[Backport 2.x] - Add Telemetry metrics framework (#10393)

Signed-off-by: Gagan Juneja <gjjuneja@amazon.com>

Author: Gaganjuneja

CHANGELOG.md

@@ -47,6 +47,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Pass parent filter to inner query in nested query ([#10246](https://github.com/opensearch-project/OpenSearch/pull/10246))
 - Disable concurrent segment search when terminate_after is used ([#10200](https://github.com/opensearch-project/OpenSearch/pull/10200))
 - Enable remote segment upload backpressure by default ([#10356](https://github.com/opensearch-project/OpenSearch/pull/10356))
+- [Metrics Framework] Add Metrics framework. ([#10241](https://github.com/opensearch-project/OpenSearch/pull/10241))
 
 ### Deprecated
 

libs/telemetry/src/main/java/org/opensearch/telemetry/metrics/Counter.java

@@ -0,0 +1,35 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
+
+package org.opensearch.telemetry.metrics;
+
+import org.opensearch.common.annotation.ExperimentalApi;
+import org.opensearch.telemetry.metrics.tags.Tags;
+
+/**
+ * Counter adds the value to the existing metric.
+ * {@opensearch.experimental}
+ */
+@ExperimentalApi
+public interface Counter {
+
+    /**
+     * add value.
+     * @param value value to be added.
+     */
+    void add(double value);
+
+    /**
+     * add value along with the attributes.
+     *
+     * @param value value to be added.
+     * @param tags  attributes/dimensions of the metric.
+     */
+    void add(double value, Tags tags);
+
+}

libs/telemetry/src/main/java/org/opensearch/telemetry/metrics/DefaultMetricsRegistry.java

@@ -0,0 +1,41 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
+
+package org.opensearch.telemetry.metrics;
+
+import java.io.IOException;
+
+/**
+ * Default implementation for {@link MetricsRegistry}
+ */
+class DefaultMetricsRegistry implements MetricsRegistry {
+    private final MetricsTelemetry metricsTelemetry;
+
+    /**
+     * Constructor
+     * @param metricsTelemetry metrics telemetry.
+     */
+    public DefaultMetricsRegistry(MetricsTelemetry metricsTelemetry) {
+        this.metricsTelemetry = metricsTelemetry;
+    }
+
+    @Override
+    public Counter createCounter(String name, String description, String unit) {
+        return metricsTelemetry.createCounter(name, description, unit);
+    }
+
+    @Override
+    public Counter createUpDownCounter(String name, String description, String unit) {
+        return metricsTelemetry.createUpDownCounter(name, description, unit);
+    }
+
+    @Override
+    public void close() throws IOException {
+        metricsTelemetry.close();
+    }
+}

libs/telemetry/src/main/java/org/opensearch/telemetry/metrics/MetricsRegistry.java

@@ -0,0 +1,39 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
+
+package org.opensearch.telemetry.metrics;
+
+import org.opensearch.common.annotation.ExperimentalApi;
+
+import java.io.Closeable;
+
+/**
+ * MetricsRegistry helps in creating the metric instruments.
+ * @opensearch.experimental
+ */
+@ExperimentalApi
+public interface MetricsRegistry extends Closeable {
+
+    /**
+     * Creates the counter.
+     * @param name name of the counter.
+     * @param description any description about the metric.
+     * @param unit unit of the metric.
+     * @return counter.
+     */
+    Counter createCounter(String name, String description, String unit);
+
+    /**
+     * Creates the upDown counter.
+     * @param name name of the upDown counter.
+     * @param description any description about the metric.
+     * @param unit unit of the metric.
+     * @return counter.
+     */
+    Counter createUpDownCounter(String name, String description, String unit);
+}

libs/telemetry/src/main/java/org/opensearch/telemetry/metrics/MetricsTelemetry.java

@@ -10,12 +10,14 @@
 
 import org.opensearch.common.annotation.ExperimentalApi;
 
+import java.io.Closeable;
+
 /**
  * Interface for metrics telemetry providers
   *
  * @opensearch.experimental
  */
 @ExperimentalApi
-public interface MetricsTelemetry {
+public interface MetricsTelemetry extends MetricsRegistry, Closeable {
 
 }

libs/telemetry/src/main/java/org/opensearch/telemetry/metrics/noop/NoopCounter.java

@@ -0,0 +1,38 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
+
+package org.opensearch.telemetry.metrics.noop;
+
+import org.opensearch.common.annotation.InternalApi;
+import org.opensearch.telemetry.metrics.Counter;
+import org.opensearch.telemetry.metrics.tags.Tags;
+
+/**
+ * No-op {@link Counter}
+ * {@opensearch.internal}
+ */
+@InternalApi
+public class NoopCounter implements Counter {
+
+    /**
+     * No-op Counter instance
+     */
+    public final static NoopCounter INSTANCE = new NoopCounter();
+
+    private NoopCounter() {}
+
+    @Override
+    public void add(double value) {
+
+    }
+
+    @Override
+    public void add(double value, Tags tags) {
+
+    }
+}

libs/telemetry/src/main/java/org/opensearch/telemetry/metrics/noop/NoopMetricsRegistry.java

@@ -0,0 +1,45 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
+
+package org.opensearch.telemetry.metrics.noop;
+
+import org.opensearch.common.annotation.InternalApi;
+import org.opensearch.telemetry.metrics.Counter;
+import org.opensearch.telemetry.metrics.MetricsRegistry;
+
+import java.io.IOException;
+
+/**
+ *No-op {@link MetricsRegistry}
+ * {@opensearch.internal}
+ */
+@InternalApi
+public class NoopMetricsRegistry implements MetricsRegistry {
+
+    /**
+     * No-op Meter instance
+     */
+    public final static NoopMetricsRegistry INSTANCE = new NoopMetricsRegistry();
+
+    private NoopMetricsRegistry() {}
+
+    @Override
+    public Counter createCounter(String name, String description, String unit) {
+        return NoopCounter.INSTANCE;
+    }
+
+    @Override
+    public Counter createUpDownCounter(String name, String description, String unit) {
+        return NoopCounter.INSTANCE;
+    }
+
+    @Override
+    public void close() throws IOException {
+
+    }
+}

libs/telemetry/src/main/java/org/opensearch/telemetry/metrics/noop/package-info.java

@@ -0,0 +1,16 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
+
+/**
+ * Contains metrics related classes
+ * {@opensearch.internal}
+ */
+@InternalApi
+package org.opensearch.telemetry.metrics.noop;
+
+import org.opensearch.common.annotation.InternalApi;

libs/telemetry/src/main/java/org/opensearch/telemetry/metrics/tags/Tags.java

@@ -0,0 +1,99 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
+
+package org.opensearch.telemetry.metrics.tags;
+
+import org.opensearch.common.annotation.ExperimentalApi;
+
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Objects;
+
+/**
+ * Class to create tags for a meter.
+ *
+ * @opensearch.experimental
+ */
+@ExperimentalApi
+public class Tags {
+    private final Map<String, Object> tagsMap;
+    /**
+     * Empty value.
+     */
+    public final static Tags EMPTY = new Tags(Collections.emptyMap());
+
+    /**
+     * Factory method.
+     * @return tags.
+     */
+    public static Tags create() {
+        return new Tags(new HashMap<>());
+    }
+
+    /**
+     * Constructor.
+     */
+    private Tags(Map<String, Object> tagsMap) {
+        this.tagsMap = tagsMap;
+    }
+
+    /**
+     * Add String attribute.
+     * @param key key
+     * @param value value
+     * @return Same instance.
+     */
+    public Tags addTag(String key, String value) {
+        Objects.requireNonNull(value, "value cannot be null");
+        tagsMap.put(key, value);
+        return this;
+    }
+
+    /**
+     * Add long attribute.
+     * @param key key
+     * @param value value
+     * @return Same instance.
+     */
+    public Tags addTag(String key, long value) {
+        tagsMap.put(key, value);
+        return this;
+    };
+
+    /**
+     * Add double attribute.
+     * @param key key
+     * @param value value
+     * @return Same instance.
+     */
+    public Tags addTag(String key, double value) {
+        tagsMap.put(key, value);
+        return this;
+    };
+
+    /**
+     * Add boolean attribute.
+     * @param key key
+     * @param value value
+     * @return Same instance.
+     */
+    public Tags addTag(String key, boolean value) {
+        tagsMap.put(key, value);
+        return this;
+    };
+
+    /**
+     * Returns the attribute map.
+     * @return tags map
+     */
+    public Map<String, ?> getTagsMap() {
+        return Collections.unmodifiableMap(tagsMap);
+    }
+
+}

libs/telemetry/src/main/java/org/opensearch/telemetry/metrics/tags/package-info.java

@@ -0,0 +1,16 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
+
+/**
+ * Contains metrics related classes
+ * @opensearch.experimental
+ */
+@ExperimentalApi
+package org.opensearch.telemetry.metrics.tags;
+
+import org.opensearch.common.annotation.ExperimentalApi;

libs/telemetry/src/main/java/org/opensearch/telemetry/tracing/TracingTelemetry.java

@@ -35,9 +35,4 @@ public interface TracingTelemetry extends Closeable {
      */
     TracingContextPropagator getContextPropagator();
 
-    /**
-     * closes the resource
-     */
-    void close();
-
 }