[AURON #1850] Add FlinkArrowUtils for Flink-Arrow type conversion

.gitignore

@@ -60,4 +60,7 @@ common/src/main/resources/auron-build-info.properties
 
 
 .flattened-pom.xml
-dependency-reduced-pom.xml
+dependency-reduced-pom.xml
+
+#lsp
+*.prefs

auron-flink-extension/auron-flink-runtime/pom.xml

@@ -38,6 +38,41 @@
       <artifactId>proto</artifactId>
       <version>${project.version}</version>
     </dependency>
+
+    <!-- Arrow dependencies -->
+    <dependency>
+      <groupId>org.apache.arrow</groupId>
+      <artifactId>arrow-c-data</artifactId>
+    </dependency>
+    <dependency>
+      <groupId>org.apache.arrow</groupId>
+      <artifactId>arrow-memory-unsafe</artifactId>
+    </dependency>
+    <dependency>
+      <groupId>org.apache.arrow</groupId>
+      <artifactId>arrow-vector</artifactId>
+    </dependency>
+    <dependency>
+      <groupId>org.apache.flink</groupId>
+      <artifactId>flink-table-common</artifactId>
+      <version>${flink.version}</version>
+      <scope>provided</scope>
+    </dependency>
+
+    <!-- Test dependencies -->
+    <dependency>
+      <groupId>org.apache.auron</groupId>
+      <artifactId>auron-core</artifactId>
+      <version>${project.version}</version>
+      <type>test-jar</type>
+      <scope>test</scope>
+    </dependency>
+    <dependency>
+      <groupId>org.junit.jupiter</groupId>
+      <artifactId>junit-jupiter-api</artifactId>
+      <version>${junit.jupiter.version}</version>
+      <scope>test</scope>
+    </dependency>
   </dependencies>
 
 </project>

auron-flink-extension/auron-flink-runtime/src/main/java/org/apache/auron/flink/arrow/FlinkArrowUtils.java

@@ -0,0 +1,193 @@
+/*
+ * 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.auron.flink.arrow;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.apache.arrow.memory.BufferAllocator;
+import org.apache.arrow.memory.RootAllocator;
+import org.apache.arrow.vector.complex.MapVector;
+import org.apache.arrow.vector.types.DateUnit;
+import org.apache.arrow.vector.types.FloatingPointPrecision;
+import org.apache.arrow.vector.types.TimeUnit;
+import org.apache.arrow.vector.types.pojo.ArrowType;
+import org.apache.arrow.vector.types.pojo.Field;
+import org.apache.arrow.vector.types.pojo.FieldType;
+import org.apache.arrow.vector.types.pojo.Schema;
+import org.apache.flink.table.types.logical.ArrayType;
+import org.apache.flink.table.types.logical.BigIntType;
+import org.apache.flink.table.types.logical.BinaryType;
+import org.apache.flink.table.types.logical.BooleanType;
+import org.apache.flink.table.types.logical.CharType;
+import org.apache.flink.table.types.logical.DateType;
+import org.apache.flink.table.types.logical.DecimalType;
+import org.apache.flink.table.types.logical.DoubleType;
+import org.apache.flink.table.types.logical.FloatType;
+import org.apache.flink.table.types.logical.IntType;
+import org.apache.flink.table.types.logical.LocalZonedTimestampType;
+import org.apache.flink.table.types.logical.LogicalType;
+import org.apache.flink.table.types.logical.MapType;
+import org.apache.flink.table.types.logical.NullType;
+import org.apache.flink.table.types.logical.RowType;
+import org.apache.flink.table.types.logical.SmallIntType;
+import org.apache.flink.table.types.logical.TimeType;
+import org.apache.flink.table.types.logical.TimestampType;
+import org.apache.flink.table.types.logical.TinyIntType;
+import org.apache.flink.table.types.logical.VarBinaryType;
+import org.apache.flink.table.types.logical.VarCharType;
+
+/**
+ * Utility class for converting Flink {@link LogicalType} instances to Arrow types, fields and schemas.
+ */
+public class FlinkArrowUtils {
+
+    /**
+     * Root allocator for Arrow memory management.
+     */
+    public static final RootAllocator ROOT_ALLOCATOR = new RootAllocator(Long.MAX_VALUE);
+
+    static {
+        Runtime.getRuntime().addShutdownHook(new Thread(ROOT_ALLOCATOR::close));
+    }
+
+    /**
+     * Creates a child allocator from the root allocator.
+     *
+     * @param name Name for the child allocator
+     * @return A new child allocator
+     */
+    public static BufferAllocator createChildAllocator(String name) {
+        return ROOT_ALLOCATOR.newChildAllocator(name, 0, Long.MAX_VALUE);
+    }
+
+    /**
+     * Converts a Flink LogicalType to Arrow ArrowType.
+     *
+     * @param logicalType The Flink logical type
+     * @return The corresponding Arrow type
+     * @throws UnsupportedOperationException if the type is not supported
+     */
+    public static ArrowType toArrowType(LogicalType logicalType) {
+        if (logicalType instanceof NullType) {
+            return ArrowType.Null.INSTANCE;
+        } else if (logicalType instanceof BooleanType) {
+            return ArrowType.Bool.INSTANCE;
+        } else if (logicalType instanceof TinyIntType) {
+            return new ArrowType.Int(8, true);
+        } else if (logicalType instanceof SmallIntType) {
+            return new ArrowType.Int(16, true);
+        } else if (logicalType instanceof IntType) {
+            return new ArrowType.Int(32, true);
+        } else if (logicalType instanceof BigIntType) {
+            return new ArrowType.Int(64, true);
+        } else if (logicalType instanceof FloatType) {
+            return new ArrowType.FloatingPoint(FloatingPointPrecision.SINGLE);
+        } else if (logicalType instanceof DoubleType) {
+            return new ArrowType.FloatingPoint(FloatingPointPrecision.DOUBLE);
+        } else if (logicalType instanceof VarCharType || logicalType instanceof CharType) {
+            return ArrowType.Utf8.INSTANCE;
+        } else if (logicalType instanceof VarBinaryType || logicalType instanceof BinaryType) {
+            return ArrowType.Binary.INSTANCE;
+        } else if (logicalType instanceof DecimalType) {
+            DecimalType decimalType = (DecimalType) logicalType;
+            // Note: Arrow Java only has DecimalVector (128-bit) and Decimal256Vector (256-bit).
+            // There's no Decimal64Vector, so we always use 128-bit to match the actual storage.
+            // Setting bitWidth=64 would cause FFI export issues since the actual data is 128-bit.
+            return new ArrowType.Decimal(decimalType.getPrecision(), decimalType.getScale(), 128);
+        } else if (logicalType instanceof DateType) {
+            return new ArrowType.Date(DateUnit.DAY);
+        } else if (logicalType instanceof TimeType) {
+            // Flink TimeType stores time as milliseconds (int), convert to Arrow Time64 (microseconds)
+            return new ArrowType.Time(TimeUnit.MICROSECOND, 64);
+        } else if (logicalType instanceof TimestampType) {
+            return new ArrowType.Timestamp(TimeUnit.MICROSECOND, null);
+        } else if (logicalType instanceof LocalZonedTimestampType) {
+            // LocalZonedTimestampType is similar to TimestampType but with UTC timezone
+            return new ArrowType.Timestamp(TimeUnit.MICROSECOND, "UTC");
+        } else {
+            throw new UnsupportedOperationException("Unsupported Flink type: " + logicalType.asSummaryString());
+        }
+    }
+
+    /**
+     * Converts a Flink LogicalType to an Arrow Field.
+     *
+     * @param name        The field name
+     * @param logicalType The Flink logical type
+     * @param nullable    Whether the field is nullable
+     * @return The corresponding Arrow Field
+     */
+    public static Field toArrowField(String name, LogicalType logicalType, boolean nullable) {
+        if (logicalType instanceof ArrayType) {
+            ArrayType arrayType = (ArrayType) logicalType;
+            LogicalType elementType = arrayType.getElementType();
+            FieldType fieldType = new FieldType(nullable, ArrowType.List.INSTANCE, null);
+            Field elementField = toArrowField("element", elementType, elementType.isNullable());
+            List<Field> children = new ArrayList<>();
+            children.add(elementField);
+            return new Field(name, fieldType, children);
+        } else if (logicalType instanceof RowType) {
+            RowType rowType = (RowType) logicalType;
+            FieldType fieldType = new FieldType(nullable, ArrowType.Struct.INSTANCE, null);
+            List<Field> children = new ArrayList<>();
+            for (RowType.RowField field : rowType.getFields()) {
+                children.add(toArrowField(field.getName(), field.getType(), field.getType().isNullable()));
+            }
+            return new Field(name, fieldType, children);
+        } else if (logicalType instanceof MapType) {
+            MapType mapType = (MapType) logicalType;
+            LogicalType keyType = mapType.getKeyType();
+            LogicalType valueType = mapType.getValueType();
+
+            // Create entries field (struct<key, value>)
+            FieldType entriesFieldType = new FieldType(false, ArrowType.Struct.INSTANCE, null);
+            List<Field> entriesChildren = new ArrayList<>();
+            entriesChildren.add(toArrowField(MapVector.KEY_NAME, keyType, false));
+            entriesChildren.add(toArrowField(MapVector.VALUE_NAME, valueType, valueType.isNullable()));
+            Field entriesField = new Field(MapVector.DATA_VECTOR_NAME, entriesFieldType, entriesChildren);
+
+            // Create map field
+            FieldType mapFieldType = new FieldType(nullable, new ArrowType.Map(false), null);
+            List<Field> mapChildren = new ArrayList<>();
+            mapChildren.add(entriesField);
+            return new Field(name, mapFieldType, mapChildren);
+        } else {
+            ArrowType arrowType = toArrowType(logicalType);
+            FieldType fieldType = new FieldType(nullable, arrowType, null);
+            return new Field(name, fieldType, new ArrayList<>());
+        }
+    }
+
+    /**
+     * Converts a Flink RowType to an Arrow Schema.
+     *
+     * @param rowType The Flink row type
+     * @return The corresponding Arrow Schema
+     */
+    public static Schema toArrowSchema(RowType rowType) {
+        List<Field> fields = new ArrayList<>();
+        for (RowType.RowField field : rowType.getFields()) {
+            fields.add(toArrowField(field.getName(), field.getType(), field.getType().isNullable()));
+        }
+        return new Schema(fields);
+    }
+
+    private FlinkArrowUtils() {
+        // Utility class
+    }
+}