add rpc metrics conventions implement

add rpc metrics conventions implement

fix AutoValue State

fix AutoValue State

update RpcClientMetrics Visibility

update RpcClientMetrics Visibility

update the filed serverDurationHistogram be final

update the filed serverDurationHistogram be final

update MetricsView code style

update RpcClientMetrics code style

update RpcServerMetrics code style

update MetricsView doc

update MetricsView doc

instrumentation-api/src/main/java/io/opentelemetry/instrumentation/api/instrumenter/rpc/MetricsView.java

@@ -0,0 +1,59 @@
+package io.opentelemetry.instrumentation.api.instrumenter.rpc;
+
+import io.opentelemetry.api.common.AttributeKey;
+import io.opentelemetry.api.common.Attributes;
+import io.opentelemetry.api.common.AttributesBuilder;
+import io.opentelemetry.semconv.trace.attributes.SemanticAttributes;
+import java.util.HashSet;
+import java.util.Set;
+import java.util.function.BiConsumer;
+
+/**
+ * filter rpc metrics unnecessary attributes.
+ */
+public class MetricsView {
+
+  private static final Set<AttributeKey> recommended = buildRecommended();
+  private static final Set<AttributeKey> optional = buildOptional();
+
+  private static Set<AttributeKey> buildRecommended() {
+    // the list of Recommended metrics attributes is from
+    // https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/metrics/semantic_conventions/rpc.md#attributes
+    Set<AttributeKey> view = new HashSet<>();
+    view.add(SemanticAttributes.RPC_SYSTEM);
+    view.add(SemanticAttributes.RPC_SERVICE);
+    view.add(SemanticAttributes.RPC_METHOD);
+    return view;
+  }
+
+  private static Set<AttributeKey> buildOptional() {
+    // the list of Recommended metrics attributes is from
+    // https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/metrics/semantic_conventions/rpc.md#attributes
+    Set<AttributeKey> view = new HashSet<>();
+    view.add(SemanticAttributes.NET_PEER_IP);
+    view.add(SemanticAttributes.NET_PEER_NAME);
+    view.add(SemanticAttributes.NET_PEER_PORT);
+    view.add(SemanticAttributes.NET_TRANSPORT);
+    return view;
+  }
+
+  static Attributes applyRpcView(Attributes startAttributes, Attributes endAttributes) {
+    Attributes attributes = startAttributes.toBuilder().putAll(endAttributes).build();
+    AttributesBuilder filtered = Attributes.builder();
+    applyView(filtered, attributes, recommended);
+    applyView(filtered, attributes, optional);
+    return filtered.build();
+  }
+
+  @SuppressWarnings("unchecked")
+  private static void applyView(
+      AttributesBuilder filtered, Attributes attributes, Set<AttributeKey> view) {
+    attributes.forEach(
+        (BiConsumer<AttributeKey, Object>)
+            (key, value) -> {
+              if (view.contains(key)) {
+                filtered.put(key, value);
+              }
+            });
+  }
+}

instrumentation-api/src/main/java/io/opentelemetry/instrumentation/api/instrumenter/rpc/RpcClientMetrics.java

@@ -0,0 +1,77 @@
+package io.opentelemetry.instrumentation.api.instrumenter.rpc;
+
+import com.google.auto.value.AutoValue;
+import io.opentelemetry.api.common.Attributes;
+import io.opentelemetry.api.metrics.LongHistogram;
+import io.opentelemetry.api.metrics.Meter;
+import io.opentelemetry.context.Context;
+import io.opentelemetry.context.ContextKey;
+import io.opentelemetry.instrumentation.api.annotations.UnstableApi;
+import io.opentelemetry.instrumentation.api.instrumenter.RequestListener;
+import io.opentelemetry.instrumentation.api.instrumenter.RequestMetrics;
+import java.util.concurrent.TimeUnit;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * guide from https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/metrics/semantic_conventions/rpc.md#rpc-client
+ */
+@UnstableApi
+public class RpcClientMetrics implements RequestListener {
+
+  private static final ContextKey<RpcClientMetrics.State> RPC_CLIENT_REQUEST_METRICS_STATE =
+      ContextKey.named("rpc-client-request-metrics-state");
+
+  private static final Logger logger = LoggerFactory.getLogger(RpcClientMetrics.class);
+
+  /**
+   * measures duration of outbound RPC.
+   */
+  private final LongHistogram clientDurationHistogram;
+
+  private RpcClientMetrics(Meter meter) {
+    clientDurationHistogram = meter
+        .histogramBuilder("rpc.client.duration")
+        .setDescription("measures duration of outbound RPC")
+        .setUnit("milliseconds")
+        .ofLongs().build();
+  }
+
+  /**
+   * Returns a {@link RequestMetrics} which can be used to enable recording of {@link
+   * RpcClientMetrics} on an {@link
+   * io.opentelemetry.instrumentation.api.instrumenter.InstrumenterBuilder}
+   * method addRequestMetrics().
+   */
+  @UnstableApi
+  public static RequestMetrics get() {
+    return RpcClientMetrics::new;
+  }
+
+  @Override
+  public Context start(Context context, Attributes startAttributes, long startNanos) {
+    return context.with(RPC_CLIENT_REQUEST_METRICS_STATE,
+        new AutoValue_RpcClientMetrics_State(startAttributes, startNanos));
+  }
+
+  @Override
+  public void end(Context context, Attributes endAttributes, long endNanos) {
+    State state = context.get(RPC_CLIENT_REQUEST_METRICS_STATE);
+    if (state == null) {
+      logger.debug(
+          "No state present when ending context {}. Cannot reset RPC request metrics.", context);
+    }
+    clientDurationHistogram.record(
+        TimeUnit.MILLISECONDS.convert(
+            endNanos - state.startTimeNanos(), TimeUnit.NANOSECONDS),
+        MetricsView.applyRpcView(state.startAttributes(), endAttributes), context);
+  }
+
+  @AutoValue
+  abstract static class State {
+
+    abstract Attributes startAttributes();
+
+    abstract long startTimeNanos();
+  }
+}

instrumentation-api/src/main/java/io/opentelemetry/instrumentation/api/instrumenter/rpc/RpcServerMetrics.java

@@ -0,0 +1,80 @@
+package io.opentelemetry.instrumentation.api.instrumenter.rpc;
+
+import com.google.auto.value.AutoValue;
+import io.opentelemetry.api.common.Attributes;
+import io.opentelemetry.api.metrics.LongHistogram;
+import io.opentelemetry.api.metrics.Meter;
+import io.opentelemetry.context.Context;
+import io.opentelemetry.context.ContextKey;
+import io.opentelemetry.instrumentation.api.annotations.UnstableApi;
+import io.opentelemetry.instrumentation.api.instrumenter.RequestListener;
+import io.opentelemetry.instrumentation.api.instrumenter.RequestMetrics;
+import java.util.concurrent.TimeUnit;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * guide from https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/metrics/semantic_conventions/rpc.md#rpc-server
+ */
+@UnstableApi
+public class RpcServerMetrics implements RequestListener {
+
+  private static final ContextKey<RpcServerMetrics.State> RPC_SERVER_REQUEST_METRICS_STATE =
+      ContextKey.named("rpc-server-request-metrics-state");
+
+  private static final Logger logger = LoggerFactory.getLogger(RpcServerMetrics.class);
+
+  /**
+   * measures duration of inbound RPC.
+   */
+  private final LongHistogram serverDurationHistogram;
+
+  private RpcServerMetrics(Meter meter) {
+    serverDurationHistogram = meter
+        .histogramBuilder("rpc.server.duration")
+        .setDescription("measures duration of inbound RPC")
+        .setUnit("milliseconds")
+        .ofLongs().build();
+  }
+
+  /**
+   * Returns a {@link RequestMetrics} which can be used to enable recording of {@link
+   * RpcServerMetrics} on an {@link
+   * io.opentelemetry.instrumentation.api.instrumenter.InstrumenterBuilder}
+   * method addRequestMetrics().
+   */
+  @UnstableApi
+  public static RequestMetrics get() {
+    return RpcServerMetrics::new;
+  }
+
+  @Override
+  public Context start(Context context, Attributes startAttributes, long startNanos) {
+    return context.with(RPC_SERVER_REQUEST_METRICS_STATE,
+        new AutoValue_RpcServerMetrics_State(startAttributes, startNanos));
+  }
+
+  @Override
+  public void end(Context context, Attributes endAttributes, long endNanos) {
+    State state = context.get(RPC_SERVER_REQUEST_METRICS_STATE);
+    if (state == null) {
+      logger.debug(
+          "No state present when ending context {}. Cannot reset RPC request metrics.", context);
+    }
+    serverDurationHistogram.record(
+        TimeUnit.MILLISECONDS.convert(
+            endNanos - state.startTimeNanos(), TimeUnit.NANOSECONDS),
+        MetricsView.applyRpcView(state.startAttributes(), endAttributes), context);
+  }
+
+  @AutoValue
+  abstract static class State {
+
+    abstract Attributes startAttributes();
+
+    abstract long startTimeNanos();
+
+  }
+}
+
+