docs(samples): update WriteComittedStream sample code to match best p…

…ractices (#1628)

* feat: Update WriteComittedStream sample code to match best practices

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samples/snippets/src/main/java/com/example/bigquerystorage/WriteCommittedStream.java

@@ -18,16 +18,23 @@
 
 // [START bigquerystorage_jsonstreamwriter_committed]
 import com.google.api.core.ApiFuture;
+import com.google.api.core.ApiFutureCallback;
+import com.google.api.core.ApiFutures;
 import com.google.cloud.bigquery.storage.v1.AppendRowsResponse;
 import com.google.cloud.bigquery.storage.v1.BigQueryWriteClient;
 import com.google.cloud.bigquery.storage.v1.CreateWriteStreamRequest;
-import com.google.cloud.bigquery.storage.v1.FinalizeWriteStreamRequest;
+import com.google.cloud.bigquery.storage.v1.Exceptions;
+import com.google.cloud.bigquery.storage.v1.Exceptions.StorageException;
+import com.google.cloud.bigquery.storage.v1.FinalizeWriteStreamResponse;
 import com.google.cloud.bigquery.storage.v1.JsonStreamWriter;
 import com.google.cloud.bigquery.storage.v1.TableName;
 import com.google.cloud.bigquery.storage.v1.WriteStream;
+import com.google.common.util.concurrent.MoreExecutors;
 import com.google.protobuf.Descriptors.DescriptorValidationException;
 import java.io.IOException;
 import java.util.concurrent.ExecutionException;
+import java.util.concurrent.Phaser;
+import javax.annotation.concurrent.GuardedBy;
 import org.json.JSONArray;
 import org.json.JSONObject;
 
@@ -45,13 +52,60 @@ public static void runWriteCommittedStream()
 
   public static void writeCommittedStream(String projectId, String datasetName, String tableName)
       throws DescriptorValidationException, InterruptedException, IOException {
+    BigQueryWriteClient client = BigQueryWriteClient.create();
+    TableName parentTable = TableName.of(projectId, datasetName, tableName);
 
-    try (BigQueryWriteClient client = BigQueryWriteClient.create()) {
+    DataWriter writer = new DataWriter();
+    // One time initialization.
+    writer.initialize(parentTable, client);
+
+    try {
+      // Write two batches of fake data to the stream, each with 10 JSON records.  Data may be
+      // batched up to the maximum request size:
+      // https://cloud.google.com/bigquery/quotas#write-api-limits
+      long offset = 0;
+      for (int i = 0; i < 2; i++) {
+        // Create a JSON object that is compatible with the table schema.
+        JSONArray jsonArr = new JSONArray();
+        for (int j = 0; j < 10; j++) {
+          JSONObject record = new JSONObject();
+          record.put("col1", String.format("batch-record %03d-%03d", i, j));
+          jsonArr.put(record);
+        }
+        writer.append(jsonArr, offset);
+        offset += jsonArr.length();
+      }
+    } catch (ExecutionException e) {
+      // If the wrapped exception is a StatusRuntimeException, check the state of the operation.
+      // If the state is INTERNAL, CANCELLED, or ABORTED, you can retry. For more information, see:
+      // https://grpc.github.io/grpc-java/javadoc/io/grpc/StatusRuntimeException.html
+      System.out.println("Failed to append records. \n" + e);
+    }
+
+    // Final cleanup for the stream.
+    writer.cleanup(client);
+    System.out.println("Appended records successfully.");
+  }
+
+  // A simple wrapper object showing how the stateful stream writer should be used.
+  private static class DataWriter {
+
+    private JsonStreamWriter streamWriter;
+    // Track the number of in-flight requests to wait for all responses before shutting down.
+    private final Phaser inflightRequestCount = new Phaser(1);
+
+    private final Object lock = new Object();
+
+    @GuardedBy("lock")
+    private RuntimeException error = null;
+
+    void initialize(TableName parentTable, BigQueryWriteClient client)
+        throws IOException, DescriptorValidationException, InterruptedException {
       // Initialize a write stream for the specified table.
       // For more information on WriteStream.Type, see:
-      // https://googleapis.dev/java/google-cloud-bigquerystorage/latest/com/google/cloud/bigquery/storage/v1beta2/WriteStream.Type.html
+      // https://googleapis.dev/java/google-cloud-bigquerystorage/latest/com/google/cloud/bigquery/storage/v1/WriteStream.Type.html
       WriteStream stream = WriteStream.newBuilder().setType(WriteStream.Type.COMMITTED).build();
-      TableName parentTable = TableName.of(projectId, datasetName, tableName);
+
       CreateWriteStreamRequest createWriteStreamRequest =
           CreateWriteStreamRequest.newBuilder()
               .setParent(parentTable.toString())
@@ -62,37 +116,79 @@ public static void writeCommittedStream(String projectId, String datasetName, St
       // Use the JSON stream writer to send records in JSON format.
       // For more information about JsonStreamWriter, see:
       // https://googleapis.dev/java/google-cloud-bigquerystorage/latest/com/google/cloud/bigquery/storage/v1/JsonStreamWriter.html
-      try (JsonStreamWriter writer =
-          JsonStreamWriter.newBuilder(writeStream.getName(), writeStream.getTableSchema())
-              .build()) {
-        // Write two batches to the stream, each with 10 JSON records. A writer should be
-        // used for as much writes as possible. Creating a writer for just one write is an
-        // antipattern.
-        for (int i = 0; i < 2; i++) {
-          // Create a JSON object that is compatible with the table schema.
-          JSONArray jsonArr = new JSONArray();
-          for (int j = 0; j < 10; j++) {
-            JSONObject record = new JSONObject();
-            record.put("col1", String.format("record %03d-%03d", i, j));
-            jsonArr.put(record);
-          }
+      streamWriter =
+          JsonStreamWriter.newBuilder(writeStream.getName(), writeStream.getTableSchema()).build();
+    }
 
-          // To detect duplicate records, pass the index as the record offset.
-          // To disable deduplication, omit the offset or use WriteStream.Type.DEFAULT.
-          ApiFuture<AppendRowsResponse> future = writer.append(jsonArr, /*offset=*/ i * 10);
-          AppendRowsResponse response = future.get();
+    public void append(JSONArray data, long offset)
+        throws DescriptorValidationException, IOException, ExecutionException {
+      synchronized (this.lock) {
+        // If earlier appends have failed, we need to reset before continuing.
+        if (this.error != null) {
+          throw this.error;
         }
-        // Finalize the stream after use.
-        FinalizeWriteStreamRequest finalizeWriteStreamRequest =
-            FinalizeWriteStreamRequest.newBuilder().setName(writeStream.getName()).build();
-        client.finalizeWriteStream(finalizeWriteStreamRequest);
       }
-      System.out.println("Appended records successfully.");
-    } catch (ExecutionException e) {
-      // If the wrapped exception is a StatusRuntimeException, check the state of the operation.
-      // If the state is INTERNAL, CANCELLED, or ABORTED, you can retry. For more information, see:
-      // https://grpc.github.io/grpc-java/javadoc/io/grpc/StatusRuntimeException.html
-      System.out.println("Failed to append records. \n" + e.toString());
+      // Append asynchronously for increased throughput.
+      ApiFuture<AppendRowsResponse> future = streamWriter.append(data, offset);
+      ApiFutures.addCallback(
+          future, new DataWriter.AppendCompleteCallback(this), MoreExecutors.directExecutor());
+      // Increase the count of in-flight requests.
+      inflightRequestCount.register();
+    }
+
+    public void cleanup(BigQueryWriteClient client) {
+      // Wait for all in-flight requests to complete.
+      inflightRequestCount.arriveAndAwaitAdvance();
+
+      // Close the connection to the server.
+      streamWriter.close();
+
+      // Verify that no error occurred in the stream.
+      synchronized (this.lock) {
+        if (this.error != null) {
+          throw this.error;
+        }
+      }
+
+      // Finalize the stream.
+      FinalizeWriteStreamResponse finalizeResponse =
+          client.finalizeWriteStream(streamWriter.getStreamName());
+      System.out.println("Rows written: " + finalizeResponse.getRowCount());
+    }
+
+    public String getStreamName() {
+      return streamWriter.getStreamName();
+    }
+
+    static class AppendCompleteCallback implements ApiFutureCallback<AppendRowsResponse> {
+
+      private final DataWriter parent;
+
+      public AppendCompleteCallback(DataWriter parent) {
+        this.parent = parent;
+      }
+
+      public void onSuccess(AppendRowsResponse response) {
+        System.out.format("Append %d success\n", response.getAppendResult().getOffset().getValue());
+        done();
+      }
+
+      public void onFailure(Throwable throwable) {
+        synchronized (this.parent.lock) {
+          if (this.parent.error == null) {
+            StorageException storageException = Exceptions.toStorageException(throwable);
+            this.parent.error =
+                (storageException != null) ? storageException : new RuntimeException(throwable);
+          }
+        }
+        System.out.format("Error: %s\n", throwable.toString());
+        done();
+      }
+
+      private void done() {
+        // Reduce the count of in-flight requests.
+        this.parent.inflightRequestCount.arriveAndDeregister();
+      }
     }
   }
 }