fix: add dataflow trace id support

google-cloud-bigquerystorage/src/main/java/com/google/cloud/bigquery/storage/v1beta2/StreamWriter.java

@@ -91,6 +91,8 @@ public class StreamWriter implements AutoCloseable {
   private final String streamName;
   private final String tableName;
 
+  private final String traceId;
+
   private final BatchingSettings batchingSettings;
   private final RetrySettings retrySettings;
   private BigQueryWriteSettings stubSettings;
@@ -151,6 +153,7 @@ private StreamWriter(Builder builder)
       tableName = matcher.group(1);
     }
 
+    this.traceId = builder.traceId;
     this.batchingSettings = builder.batchingSettings;
     this.retrySettings = builder.retrySettings;
     this.messagesBatch = new MessagesBatch(batchingSettings, this.streamName, this);
@@ -477,6 +480,11 @@ private AppendRowsRequest getMergedRequest() throws IllegalStateException {
               "The first message on the connection must have writer schema set");
         }
         requestBuilder.setWriteStream(streamName);
+        if (!inflightRequests.get(0).message.getTraceId().isEmpty()) {
+          requestBuilder.setTraceId(inflightRequests.get(0).message.getTraceId());
+        } else if (streamWriter.traceId != null) {
+          requestBuilder.setTraceId(streamWriter.traceId);
+        }
       }
       return requestBuilder.setProtoRows(data.build()).build();
     }
@@ -660,6 +668,8 @@ public static final class Builder {
     private String streamOrTableName;
     private String endpoint = BigQueryWriteSettings.getDefaultEndpoint();
 
+    private String traceId;
+
     private BigQueryWriteClient client = null;
 
     // Batching options
@@ -814,6 +824,12 @@ public Builder createDefaultStream() {
       return this;
     }
 
+    /** Mark the request as coming from Dataflow. */
+    public Builder setDataflowTraceId() {
+      this.traceId = "Dataflow";
+      return this;
+    }
+
     /** Builds the {@code StreamWriter}. */
     public StreamWriter build() throws IllegalArgumentException, IOException, InterruptedException {
       return new StreamWriter(this);

google-cloud-bigquerystorage/src/test/java/com/google/cloud/bigquery/storage/v1beta2/StreamWriterTest.java

@@ -993,4 +993,26 @@ public void testFlushAllFailed() throws Exception {
 
     writer.close();
   }
+
+  @Test
+  public void testDatasetTraceId() throws Exception {
+    StreamWriter writer =
+        getTestStreamWriterBuilder()
+            .setBatchingSettings(
+                StreamWriter.Builder.DEFAULT_BATCHING_SETTINGS
+                    .toBuilder()
+                    .setElementCountThreshold(1L)
+                    .build())
+            .setDataflowTraceId()
+            .build();
+    testBigQueryWrite.addResponse(AppendRowsResponse.newBuilder().build());
+    testBigQueryWrite.addResponse(AppendRowsResponse.newBuilder().build());
+
+    ApiFuture<AppendRowsResponse> appendFuture1 = sendTestMessage(writer, new String[] {"A"});
+    ApiFuture<AppendRowsResponse> appendFuture2 = sendTestMessage(writer, new String[] {"B"});
+    appendFuture1.get();
+    appendFuture2.get();
+    assertEquals("Dataflow", testBigQueryWrite.getAppendRequests().get(0).getTraceId());
+    assertEquals("", testBigQueryWrite.getAppendRequests().get(1).getTraceId());
+  }
 }