Add producer for arrays type

Author: martin-traverse

adapter/avro/src/main/java/org/apache/arrow/adapter/avro/ArrowToAvroUtils.java

@@ -17,6 +17,7 @@
 
 package org.apache.arrow.adapter.avro;
 
+import org.apache.arrow.adapter.avro.producers.AvroArraysProducer;
 import org.apache.arrow.adapter.avro.producers.AvroBooleanProducer;
 import org.apache.arrow.adapter.avro.producers.AvroBytesProducer;
 import org.apache.arrow.adapter.avro.producers.AvroDoubleProducer;
@@ -54,6 +55,7 @@
 import org.apache.arrow.vector.TimeStampMilliVector;
 import org.apache.arrow.vector.VarBinaryVector;
 import org.apache.arrow.vector.VarCharVector;
+import org.apache.arrow.vector.complex.ListVector;
 import org.apache.arrow.vector.complex.StructVector;
 import org.apache.arrow.vector.types.Types;
 
@@ -147,6 +149,13 @@ private static BaseAvroProducer<?> createProducer(FieldVector vector, boolean nu
         }
         return new AvroStructProducer(structVector, childProducers);
 
+      case LIST:
+
+        ListVector listVector = (ListVector) vector;
+        FieldVector itemVector = listVector.getDataVector();
+        Producer<?> itemProducer = createProducer(itemVector, itemVector.getField().isNullable());
+        return new AvroArraysProducer(listVector, itemProducer);
+
       // Not all Arrow types are supported for encoding (yet)!
 
       default:

adapter/avro/src/main/java/org/apache/arrow/adapter/avro/producers/AvroArraysProducer.java

@@ -0,0 +1,65 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.arrow.adapter.avro.producers;
+
+import java.io.IOException;
+
+import org.apache.arrow.vector.FieldVector;
+import org.apache.arrow.vector.complex.ListVector;
+import org.apache.avro.io.Encoder;
+
+/**
+ * Producer which produces array type values to an Avro encoder.
+ * Writes the data from a {@link ListVector}.
+ */
+public class AvroArraysProducer extends BaseAvroProducer<ListVector> {
+
+  private final Producer<? extends FieldVector> delegate;
+
+  /** Instantiate an ArraysProducer. */
+  public AvroArraysProducer(ListVector vector, Producer<? extends FieldVector> delegate) {
+    super(vector);
+    this.delegate = delegate;
+  }
+
+  @Override
+  public void produce(Encoder encoder) throws IOException {
+
+    int startOffset = vector.getOffsetBuffer().getInt(currentIndex * (long) Integer.BYTES);
+    int endOffset = vector.getOffsetBuffer().getInt((currentIndex + 1) * (long) Integer.BYTES);
+    int nItems = endOffset - startOffset;
+
+    encoder.writeArrayStart();
+    encoder.setItemCount(nItems);
+
+    for (int i = 0; i < nItems; i++) {
+      encoder.startItem();
+      delegate.produce(encoder);
+    }
+
+    encoder.writeArrayEnd();
+    currentIndex++;
+  }
+
+  @Override
+  @SuppressWarnings("unchecked")
+  public boolean resetValueVector(ListVector vector) {
+    ((Producer<FieldVector>) delegate).resetValueVector(vector.getDataVector());
+    return super.resetValueVector(vector);
+  }
+}