[FIP-37] Add bitmap infrastructure: BitmapUtils, RoaringBitmapSerializer, AbstractRbAggFunction

fluss-flink/fluss-flink-common/pom.xml

@@ -95,6 +95,13 @@
             <scope>provided</scope>
         </dependency>
 
+        <!-- RoaringBitmap for bitmap SQL functions (FIP-37) -->
+        <dependency>
+            <groupId>org.roaringbitmap</groupId>
+            <artifactId>RoaringBitmap</artifactId>
+            <version>${roaringbitmap.version}</version>
+        </dependency>
+
         <!-- test dependency -->
         <dependency>
             <groupId>org.apache.fluss</groupId>

fluss-flink/fluss-flink-common/src/main/java/org/apache/fluss/flink/functions/bitmap/AbstractRbAggFunction.java

@@ -0,0 +1,77 @@
+/*
+ * 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.fluss.flink.functions.bitmap;
+
+import org.apache.flink.api.common.typeinfo.TypeInformation;
+import org.apache.flink.table.annotation.DataTypeHint;
+import org.apache.flink.table.annotation.FunctionHint;
+import org.apache.flink.table.functions.AggregateFunction;
+import org.roaringbitmap.RoaringBitmap;
+
+import javax.annotation.Nullable;
+
+import java.io.IOException;
+
+/**
+ * Shared base for bitmap aggregate UDFs that use {@link RoaringBitmap} as the accumulator.
+ *
+ * <p>The {@code @FunctionHint} annotation with {@code accumulator = @DataTypeHint("RAW")} tells
+ * Flink's Table planner to skip reflection-based POJO extraction and instead use the {@link
+ * TypeInformation} returned by {@link #getAccumulatorType()}, which provides the custom {@link
+ * RoaringBitmapSerializer}. Without this annotation, Flink attempts POJO field extraction on
+ * RoaringBitmap and fails.
+ */
+@FunctionHint(accumulator = @DataTypeHint(value = "RAW", bridgedTo = RoaringBitmap.class))
+abstract class AbstractRbAggFunction extends AggregateFunction<byte[], RoaringBitmap> {
+
+    @Override
+    public RoaringBitmap createAccumulator() {
+        return new RoaringBitmap();
+    }
+
+    /** Merges multiple accumulators — required for session window aggregation. */
+    public void merge(RoaringBitmap acc, Iterable<RoaringBitmap> it) {
+        for (RoaringBitmap other : it) {
+            if (other != null) {
+                acc.or(other);
+            }
+        }
+    }
+
+    public void resetAccumulator(RoaringBitmap acc) {
+        acc.clear();
+    }
+
+    @Override
+    @Nullable
+    public byte[] getValue(RoaringBitmap acc) {
+        if (acc == null || acc.isEmpty()) {
+            return null;
+        }
+        try {
+            return BitmapUtils.toBytes(acc);
+        } catch (IOException e) {
+            throw new RuntimeException("Failed to serialize bitmap accumulator.", e);
+        }
+    }
+
+    @Override
+    public TypeInformation<RoaringBitmap> getAccumulatorType() {
+        return RoaringBitmapTypeInfo.INSTANCE;
+    }
+}

fluss-flink/fluss-flink-common/src/main/java/org/apache/fluss/flink/functions/bitmap/BitmapUtils.java

@@ -0,0 +1,70 @@
+/*
+ * 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.fluss.flink.functions.bitmap;
+
+import org.roaringbitmap.RoaringBitmap;
+
+import javax.annotation.Nullable;
+
+import java.io.IOException;
+import java.nio.ByteBuffer;
+
+/**
+ * Utility methods for serializing and deserializing {@link RoaringBitmap}.
+ *
+ * <p>Uses the ByteBuffer-based serialization approach, which is the preferred method recommended by
+ * the RoaringBitmap library. This format is compatible with the server-side {@code
+ * RoaringBitmapUtils.serializeRoaringBitmap32} used by {@code FieldRoaringBitmap32Agg}.
+ */
+public final class BitmapUtils {
+
+    private BitmapUtils() {}
+
+    /**
+     * Serializes a {@link RoaringBitmap} to a byte array.
+     *
+     * @param bitmap the bitmap to serialize; null returns null
+     * @return serialized byte array, or null if input is null
+     */
+    @Nullable
+    public static byte[] toBytes(@Nullable RoaringBitmap bitmap) throws IOException {
+        if (bitmap == null) {
+            return null;
+        }
+        bitmap.runOptimize();
+        ByteBuffer buffer = ByteBuffer.allocate(bitmap.serializedSizeInBytes());
+        bitmap.serialize(buffer);
+        return buffer.array();
+    }
+
+    /**
+     * Deserializes a {@link RoaringBitmap} from a byte array.
+     *
+     * @param bytes the serialized bitmap bytes; null returns null
+     * @return deserialized RoaringBitmap, or null if input is null
+     */
+    @Nullable
+    public static RoaringBitmap fromBytes(@Nullable byte[] bytes) throws IOException {
+        if (bytes == null) {
+            return null;
+        }
+        RoaringBitmap bitmap = new RoaringBitmap();
+        bitmap.deserialize(ByteBuffer.wrap(bytes));
+        return bitmap;
+    }
+}

fluss-flink/fluss-flink-common/src/main/java/org/apache/fluss/flink/functions/bitmap/RoaringBitmapSerializer.java

@@ -0,0 +1,113 @@
+/*
+ * 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.fluss.flink.functions.bitmap;
+
+import org.apache.flink.api.common.typeutils.SimpleTypeSerializerSnapshot;
+import org.apache.flink.api.common.typeutils.TypeSerializerSnapshot;
+import org.apache.flink.api.common.typeutils.base.TypeSerializerSingleton;
+import org.apache.flink.core.memory.DataInputView;
+import org.apache.flink.core.memory.DataOutputView;
+import org.roaringbitmap.RoaringBitmap;
+
+import java.io.IOException;
+
+/**
+ * Flink {@link org.apache.flink.api.common.typeutils.TypeSerializer} for {@link RoaringBitmap}.
+ *
+ * <p>Used as the accumulator serializer for bitmap aggregate functions to ensure correct
+ * checkpoint/savepoint behavior. Without a custom serializer, Flink falls back to Kryo which is
+ * sensitive to internal class layout changes across RoaringBitmap library versions.
+ */
+public final class RoaringBitmapSerializer extends TypeSerializerSingleton<RoaringBitmap> {
+
+    public static final RoaringBitmapSerializer INSTANCE = new RoaringBitmapSerializer();
+
+    private static final long serialVersionUID = 1L;
+
+    private RoaringBitmapSerializer() {}
+
+    @Override
+    public boolean isImmutableType() {
+        return false;
+    }
+
+    @Override
+    public RoaringBitmap createInstance() {
+        return new RoaringBitmap();
+    }
+
+    @Override
+    public RoaringBitmap copy(RoaringBitmap from) {
+        return from.clone();
+    }
+
+    @Override
+    public RoaringBitmap copy(RoaringBitmap from, RoaringBitmap reuse) {
+        return from.clone();
+    }
+
+    @Override
+    public int getLength() {
+        return -1;
+    }
+
+    @Override
+    public void serialize(RoaringBitmap record, DataOutputView target) throws IOException {
+        record.runOptimize();
+        int size = record.serializedSizeInBytes();
+        target.writeInt(size);
+        byte[] bytes = BitmapUtils.toBytes(record);
+        target.write(bytes);
+    }
+
+    @Override
+    public RoaringBitmap deserialize(DataInputView source) throws IOException {
+        int size = source.readInt();
+        byte[] bytes = new byte[size];
+        source.readFully(bytes);
+        return BitmapUtils.fromBytes(bytes);
+    }
+
+    @Override
+    public RoaringBitmap deserialize(RoaringBitmap reuse, DataInputView source) throws IOException {
+        return deserialize(source);
+    }
+
+    @Override
+    public void copy(DataInputView source, DataOutputView target) throws IOException {
+        int size = source.readInt();
+        target.writeInt(size);
+        byte[] buffer = new byte[size];
+        source.readFully(buffer);
+        target.write(buffer);
+    }
+
+    @Override
+    public TypeSerializerSnapshot<RoaringBitmap> snapshotConfiguration() {
+        return new RoaringBitmapSerializerSnapshot();
+    }
+
+    /** Snapshot for {@link RoaringBitmapSerializer}. */
+    public static final class RoaringBitmapSerializerSnapshot
+            extends SimpleTypeSerializerSnapshot<RoaringBitmap> {
+
+        public RoaringBitmapSerializerSnapshot() {
+            super(() -> INSTANCE);
+        }
+    }
+}

fluss-flink/fluss-flink-common/src/main/java/org/apache/fluss/flink/functions/bitmap/RoaringBitmapTypeInfo.java

@@ -0,0 +1,95 @@
+/*
+ * 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.fluss.flink.functions.bitmap;
+
+import org.apache.flink.api.common.ExecutionConfig;
+import org.apache.flink.api.common.typeinfo.TypeInformation;
+import org.apache.flink.api.common.typeutils.TypeSerializer;
+import org.roaringbitmap.RoaringBitmap;
+
+import java.util.Objects;
+
+/**
+ * {@link TypeInformation} for {@link RoaringBitmap}.
+ *
+ * <p>Provides the custom {@link RoaringBitmapSerializer} to Flink's type system, ensuring correct
+ * checkpoint and savepoint behavior for bitmap aggregate function accumulators.
+ */
+public final class RoaringBitmapTypeInfo extends TypeInformation<RoaringBitmap> {
+
+    public static final RoaringBitmapTypeInfo INSTANCE = new RoaringBitmapTypeInfo();
+
+    private static final long serialVersionUID = 1L;
+
+    private RoaringBitmapTypeInfo() {}
+
+    @Override
+    public boolean isBasicType() {
+        return false;
+    }
+
+    @Override
+    public boolean isTupleType() {
+        return false;
+    }
+
+    @Override
+    public int getArity() {
+        return 1;
+    }
+
+    @Override
+    public int getTotalFields() {
+        return 1;
+    }
+
+    @Override
+    public Class<RoaringBitmap> getTypeClass() {
+        return RoaringBitmap.class;
+    }
+
+    @Override
+    public boolean isKeyType() {
+        return false;
+    }
+
+    @Override
+    public TypeSerializer<RoaringBitmap> createSerializer(ExecutionConfig config) {
+        return RoaringBitmapSerializer.INSTANCE;
+    }
+
+    @Override
+    public String toString() {
+        return "RoaringBitmapTypeInfo";
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        return obj instanceof RoaringBitmapTypeInfo;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(getTypeClass());
+    }
+
+    @Override
+    public boolean canEqual(Object obj) {
+        return obj instanceof RoaringBitmapTypeInfo;
+    }
+}