fix: remove tracking latency from channel priming requests

google-cloud-bigtable/src/main/java/com/google/cloud/bigtable/data/v2/stub/BigtableChannelPrimer.java

@@ -24,7 +24,9 @@
 import com.google.api.gax.grpc.ChannelPrimer;
 import com.google.api.gax.grpc.GrpcTransportChannel;
 import com.google.api.gax.rpc.FixedTransportChannelProvider;
+import com.google.api.gax.rpc.UnaryCallable;
 import com.google.auth.Credentials;
+import com.google.cloud.bigtable.data.v2.models.DefaultRowAdapter;
 import com.google.cloud.bigtable.data.v2.models.Query;
 import com.google.cloud.bigtable.data.v2.models.Row;
 import com.google.common.base.Preconditions;
@@ -143,9 +145,11 @@ private void sendPrimeRequests(ManagedChannel managedChannel) throws IOException
 
       // Prime all of the table ids in parallel
       for (String tableId : tableIds) {
+        UnaryCallable<Query, Row> callable = stub.createReadRowRawCallable(new DefaultRowAdapter());
+
         ApiFuture<Row> f =
-            stub.readRowCallable()
-                .futureCall(Query.create(tableId).rowKey(PRIMING_ROW_KEY).filter(FILTERS.block()));
+            callable.futureCall(
+                Query.create(tableId).rowKey(PRIMING_ROW_KEY).filter(FILTERS.block()));
 
         primeFutures.put(tableId, f);
       }

google-cloud-bigtable/src/main/java/com/google/cloud/bigtable/data/v2/stub/EnhancedBigtableStub.java

@@ -327,6 +327,36 @@ public <RowT> ServerStreamingCallable<Query, RowT> createReadRowsCallable(
     return traced.withDefaultCallContext(clientContext.getDefaultCallContext());
   }
 
+  /**
+   * Creates a callable chain to handle point ReadRows RPCs. The chain will:
+   *
+   * <ul>
+   *   <li>Convert a {@link Query} into a {@link com.google.bigtable.v2.ReadRowsRequest} and
+   *       dispatch the RPC.
+   *   <li>Upon receiving the response stream, it will merge the {@link
+   *       com.google.bigtable.v2.ReadRowsResponse.CellChunk}s in logical rows. The actual row
+   *       implementation can be configured in by the {@code rowAdapter} parameter.
+   *   <li>Retry/resume on failure.
+   *   <li>Filter out marker rows.
+   * </ul>
+   *
+   * <p>NOTE: the caller is responsible for adding tracing & metrics.
+   */
+  protected <RowT> UnaryCallable<Query, RowT> createReadRowRawCallable(
+      RowAdapter<RowT> rowAdapter) {
+    ServerStreamingCallable<ReadRowsRequest, RowT> readRowsCallable =
+        createReadRowsBaseCallable(
+                ServerStreamingCallSettings.<ReadRowsRequest, Row>newBuilder()
+                    .setRetryableCodes(settings.readRowSettings().getRetryableCodes())
+                    .setRetrySettings(settings.readRowSettings().getRetrySettings())
+                    .setIdleTimeout(settings.readRowSettings().getRetrySettings().getTotalTimeout())
+                    .build(),
+                rowAdapter)
+            .withDefaultCallContext(clientContext.getDefaultCallContext());
+
+    return new ReadRowsUserCallable<>(readRowsCallable, requestContext).first();
+  }
+
   /**
    * Creates a callable chain to handle point ReadRows RPCs. The chain will:
    *

google-cloud-bigtable/src/test/java/com/google/cloud/bigtable/data/v2/stub/EnhancedBigtableStubTest.java

@@ -31,6 +31,7 @@
 import com.google.api.gax.grpc.GrpcTransportChannel;
 import com.google.api.gax.rpc.FixedTransportChannelProvider;
 import com.google.api.gax.rpc.ServerStreamingCallable;
+import com.google.api.gax.rpc.UnaryCallable;
 import com.google.auth.oauth2.ServiceAccountJwtAccessCredentials;
 import com.google.bigtable.v2.BigtableGrpc;
 import com.google.bigtable.v2.MutateRowsRequest;
@@ -262,6 +263,19 @@ public void testCreateReadRowsRawCallable() throws InterruptedException {
     assertThat(fakeDataService.popLastRequest()).isEqualTo(expectedRequest2);
   }
 
+  @Test
+  public void testCreateReadRowRawCallable() throws InterruptedException {
+    UnaryCallable<Query, Row> callable =
+        enhancedBigtableStub.createReadRowRawCallable(new DefaultRowAdapter());
+
+    Query request = Query.create("table-id").rowKey("row-key");
+    callable.call(request);
+
+    ReadRowsRequest expected =
+        request.toProto(RequestContext.create(PROJECT_ID, INSTANCE_ID, APP_PROFILE_ID));
+    assertThat(fakeDataService.popLastRequest()).isEqualTo(expected);
+  }
+
   @Test
   public void testChannelPrimerConfigured() throws IOException {
     EnhancedBigtableStubSettings settings =