feat: Add DirectPath Compatible Getter to gRPC channel provider

gax-java/gax-grpc/src/main/java/com/google/api/gax/grpc/InstantiatingGrpcChannelProvider.java

@@ -370,10 +370,7 @@ private ManagedChannel createSingleChannel() throws IOException {
 
     // Check DirectPath traffic.
     boolean useDirectPathXds = false;
-    if (isDirectPathEnabled()
-        && isCredentialDirectPathCompatible()
-        && isOnComputeEngine()
-        && canUseDirectPathWithUniverseDomain()) {
+    if (canUseDirectPath()) {
       CallCredentials callCreds = MoreCallCredentials.from(credentials);
       ChannelCredentials channelCreds =
           GoogleDefaultChannelCredentials.newBuilder().callCredentials(callCreds).build();
@@ -446,6 +443,24 @@ && canUseDirectPathWithUniverseDomain()) {
     return managedChannel;
   }
 
+  /**
+   * Marked as Internal Api and intended for internal use. DirectPath must be enabled via the
+   * settings and a few other configurations/settings must also be valid for the request to go
+   * through DirectPath.
+   *
+   * <p>Checks: 1. Credentials are compatible 2.Running on Compute Engine 3. Universe Domain is
+   * configured to for the Google Default Universe
+   *
+   * @return if DirectPath is enabled for the client AND if the configurations are valid
+   */
+  @InternalApi
+  public boolean canUseDirectPath() {
+    return isDirectPathEnabled()
+        && isCredentialDirectPathCompatible()
+        && isOnComputeEngine()
+        && canUseDirectPathWithUniverseDomain();
+  }
+
   /** The endpoint to be used for the channel. */
   @Override
   public String getEndpoint() {

gax-java/gax/src/main/java/com/google/api/gax/tracing/MetricsTracer.java

@@ -61,6 +61,7 @@ public class MetricsTracer implements ApiTracer {
       "Operation has already been completed";
   private Stopwatch attemptTimer;
   private final Stopwatch operationTimer = Stopwatch.createStarted();
+  // These are RPC specific attributes and pertain to a specific API Trace
   private final Map<String, String> attributes = new HashMap<>();
   private final MetricsRecorder metricsRecorder;
   private final AtomicBoolean operationFinished;

gax-java/gax/src/main/java/com/google/api/gax/tracing/MetricsTracerFactory.java

@@ -31,6 +31,8 @@
 
 import com.google.api.core.BetaApi;
 import com.google.api.core.InternalApi;
+import com.google.common.collect.ImmutableMap;
+import java.util.Map;
 
 /**
  * A {@link ApiTracerFactory} to build instances of {@link MetricsTracer}.
@@ -45,13 +47,31 @@
 public class MetricsTracerFactory implements ApiTracerFactory {
   protected MetricsRecorder metricsRecorder;
 
+  // These are client attributes and pertain every single trace
+  private final Map<String, String> attributes;
+
+  /** Creates a MetricsTracerFactory with no additional client level attributes. */
   public MetricsTracerFactory(MetricsRecorder metricsRecorder) {
+    this(metricsRecorder, ImmutableMap.of());
+  }
+
+  /**
+   * Pass in a Map of client level attributes which will be added to every single MetricsTracer
+   * created from the ApiTracerFactory.
+   */
+  public MetricsTracerFactory(MetricsRecorder metricsRecorder, Map<String, String> attributes) {
     this.metricsRecorder = metricsRecorder;
+    this.attributes = attributes;
   }
 
   @Override
   public ApiTracer newTracer(ApiTracer parent, SpanName spanName, OperationType operationType) {
-    return new MetricsTracer(
-        MethodName.of(spanName.getClientName(), spanName.getMethodName()), metricsRecorder);
+    MetricsTracer metricsTracer =
+        new MetricsTracer(
+            MethodName.of(spanName.getClientName(), spanName.getMethodName()), metricsRecorder);
+    for (Map.Entry<String, String> attributeEntrySet : attributes.entrySet()) {
+      metricsTracer.addAttributes(attributeEntrySet.getKey(), attributeEntrySet.getValue());
+    }
+    return metricsTracer;
   }
 }

gax-java/gax/src/test/java/com/google/api/gax/tracing/MetricsTracerFactoryTest.java

@@ -33,12 +33,15 @@
 import static org.mockito.Mockito.when;
 
 import com.google.api.gax.tracing.ApiTracerFactory.OperationType;
+import com.google.common.collect.ImmutableMap;
 import com.google.common.truth.Truth;
+import java.util.Map;
 import org.junit.Before;
 import org.junit.Test;
 import org.mockito.Mock;
 
 public class MetricsTracerFactoryTest {
+  private static final int DEFAULT_ATTRIBUTES_COUNT = 2;
   @Mock private MetricsRecorder metricsRecorder;
   @Mock private ApiTracer parent;
   private SpanName spanName;
@@ -56,26 +59,39 @@ public void setUp() {
 
   @Test
   public void testNewTracer_notNull() {
-    // Call the newTracer method
     ApiTracer apiTracer = metricsTracerFactory.newTracer(parent, spanName, OperationType.Unary);
 
     // Assert that the apiTracer created has expected type and not null
-    Truth.assertThat(apiTracer).isInstanceOf(MetricsTracer.class);
     Truth.assertThat(apiTracer).isNotNull();
+    Truth.assertThat(apiTracer).isInstanceOf(MetricsTracer.class);
   }
 
   @Test
-  public void testNewTracer_HasCorrectParameters() {
-
-    // Call the newTracer method
-    ApiTracer apiTracer = metricsTracerFactory.newTracer(parent, spanName, OperationType.Unary);
+  public void testNewTracer_hasCorrectNumberAttributes_hasDefaultAttributes() {
+    MetricsTracer metricsTracer =
+        (MetricsTracer) metricsTracerFactory.newTracer(parent, spanName, OperationType.Unary);
+    Map<String, String> attributes = metricsTracer.getAttributes();
+    Truth.assertThat(attributes.size()).isEqualTo(DEFAULT_ATTRIBUTES_COUNT);
+    Truth.assertThat(attributes.get(MetricsTracer.METHOD_NAME_ATTRIBUTE))
+        .isEqualTo("testService.testMethod");
+    Truth.assertThat(attributes.get(MetricsTracer.LANGUAGE_ATTRIBUTE))
+        .isEqualTo(MetricsTracer.DEFAULT_LANGUAGE);
+  }
 
-    // Assert that the apiTracer created has expected type and not null
-    Truth.assertThat(apiTracer).isInstanceOf(MetricsTracer.class);
-    Truth.assertThat(apiTracer).isNotNull();
+  @Test
+  public void testClientAttributes_additionalClientAttributes() {
+    Map<String, String> clientAttributes =
+        ImmutableMap.of("attribute1", "value1", "attribute2", "value2");
+    MetricsTracerFactory metricsTracerFactory =
+        new MetricsTracerFactory(metricsRecorder, clientAttributes);
 
-    MetricsTracer metricsTracer = (MetricsTracer) apiTracer;
-    Truth.assertThat(metricsTracer.getAttributes().get("method_name"))
-        .isEqualTo("testService.testMethod");
+    MetricsTracer metricsTracer =
+        (MetricsTracer) metricsTracerFactory.newTracer(parent, spanName, OperationType.Unary);
+    Map<String, String> attributes = metricsTracer.getAttributes();
+    Truth.assertThat(attributes.size())
+        .isEqualTo(DEFAULT_ATTRIBUTES_COUNT + clientAttributes.size());
+    // Default attributes already tested above
+    Truth.assertThat(attributes.containsKey("attribute1")).isTrue();
+    Truth.assertThat(attributes.containsKey("attribute2")).isTrue();
   }
 }