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| 1 | +/* |
| 2 | + * Licensed to the Apache Software Foundation (ASF) under one |
| 3 | + * or more contributor license agreements. See the NOTICE file |
| 4 | + * distributed with this work for additional information |
| 5 | + * regarding copyright ownership. The ASF licenses this file |
| 6 | + * to you under the Apache License, Version 2.0 (the |
| 7 | + * "License"); you may not use this file except in compliance |
| 8 | + * with the License. You may obtain a copy of the License at |
| 9 | + * |
| 10 | + * http://www.apache.org/licenses/LICENSE-2.0 |
| 11 | + * |
| 12 | + * Unless required by applicable law or agreed to in writing, software |
| 13 | + * distributed under the License is distributed on an "AS IS" BASIS, |
| 14 | + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 15 | + * See the License for the specific language governing permissions and |
| 16 | + * limitations under the License. |
| 17 | + */ |
| 18 | + |
| 19 | +package org.apache.flink.streaming.connectors.kafka.table; |
| 20 | + |
| 21 | +import org.apache.flink.annotation.Internal; |
| 22 | +import org.apache.flink.api.common.serialization.DeserializationSchema; |
| 23 | +import org.apache.flink.table.connector.Projection; |
| 24 | +import org.apache.flink.table.connector.format.DecodingFormat; |
| 25 | +import org.apache.flink.table.connector.format.ProjectableDecodingFormat; |
| 26 | +import org.apache.flink.table.connector.source.DynamicTableSource.Context; |
| 27 | +import org.apache.flink.table.data.GenericRowData; |
| 28 | +import org.apache.flink.table.data.RowData; |
| 29 | +import org.apache.flink.table.types.DataType; |
| 30 | +import org.apache.flink.table.types.utils.DataTypeUtils; |
| 31 | + |
| 32 | +import javax.annotation.Nullable; |
| 33 | + |
| 34 | +import java.io.Serializable; |
| 35 | +import java.util.ArrayList; |
| 36 | +import java.util.Arrays; |
| 37 | +import java.util.HashMap; |
| 38 | +import java.util.List; |
| 39 | +import java.util.Map; |
| 40 | +import java.util.Objects; |
| 41 | +import java.util.Optional; |
| 42 | +import java.util.stream.Collectors; |
| 43 | + |
| 44 | +/** |
| 45 | + * Decoding messages consists of two potential steps: |
| 46 | + * |
| 47 | + * <ol> |
| 48 | + * <li>Deserialization i.e deserializing the {@code byte[]} into a {@link RowData}. This process |
| 49 | + * is handled by a {@link DeserializationSchema}. |
| 50 | + * <li>Projection i.e. projecting any required fields from the deserialized {@link RowData} |
| 51 | + * (returned by the {@link DeserializationSchema} in the first step) to their positions in the |
| 52 | + * final produced {@link RowData}. This process is handled by a {@link Projector}. |
| 53 | + * </ol> |
| 54 | + * |
| 55 | + * <p>In order to decode messages correctly, the {@link DeserializationSchema} and the {@link |
| 56 | + * Projector} need to work together. For example, the {@link Projector} needs to know the positions |
| 57 | + * of the required fields in the {@link RowData} returned by the {@link DeserializationSchema} in |
| 58 | + * order to be able to correctly set fields in the final produced {@link RowData}. |
| 59 | + * |
| 60 | + * <p>That's why we have this {@link Decoder} class. This class ensures that the returned {@link |
| 61 | + * DeserializationSchema} and {@link Projector} will work together to decode messages correctly. |
| 62 | + */ |
| 63 | +@Internal |
| 64 | +public class Decoder { |
| 65 | + |
| 66 | + /** |
| 67 | + * Can be null. Null is used inside {@link DynamicKafkaDeserializationSchema} to avoid |
| 68 | + * deserializing keys if not required. |
| 69 | + */ |
| 70 | + private final @Nullable DeserializationSchema<RowData> deserializationSchema; |
| 71 | + |
| 72 | + /** Mapping of the physical position in the key to the target position in the RowData. */ |
| 73 | + private final Projector projector; |
| 74 | + |
| 75 | + private Decoder( |
| 76 | + final DeserializationSchema<RowData> deserializationSchema, final Projector projector) { |
| 77 | + this.deserializationSchema = deserializationSchema; |
| 78 | + this.projector = projector; |
| 79 | + } |
| 80 | + |
| 81 | + /** |
| 82 | + * @param decodingFormat Optional format for decoding bytes. |
| 83 | + * @param tableDataType The data type representing the table schema. |
| 84 | + * @param dataTypeProjection Indices indicate the position of the field in the dataType |
| 85 | + * (key/value). Values indicate the position of the field in the tableSchema. |
| 86 | + * @param prefix Optional field prefix |
| 87 | + * @param projectedFields Indices indicate the position of the field in the produced Row. Values |
| 88 | + * indicate the position of the field in the table schema. |
| 89 | + * @param pushProjectionsIntoDecodingFormat if this is true and the format is a {@link |
| 90 | + * ProjectableDecodingFormat}, any {@param projectedFields} will be pushed down into the |
| 91 | + * {@link ProjectableDecodingFormat}. Otherwise, projections will be applied after |
| 92 | + * deserialization. |
| 93 | + * @return a {@link Decoder} instance. |
| 94 | + */ |
| 95 | + public static Decoder create( |
| 96 | + final Context context, |
| 97 | + final @Nullable DecodingFormat<DeserializationSchema<RowData>> decodingFormat, |
| 98 | + final DataType tableDataType, |
| 99 | + final int[] dataTypeProjection, |
| 100 | + final @Nullable String prefix, |
| 101 | + final int[][] projectedFields, |
| 102 | + final int metadataSize, |
| 103 | + final boolean pushProjectionsIntoDecodingFormat) { |
| 104 | + if (decodingFormat == null) { |
| 105 | + return Decoder.noDeserializationOrProjection(); |
| 106 | + } else { |
| 107 | + if (decodingFormat instanceof ProjectableDecodingFormat |
| 108 | + && pushProjectionsIntoDecodingFormat) { |
| 109 | + return Decoder.projectInsideDeserializer( |
| 110 | + context, |
| 111 | + (ProjectableDecodingFormat<DeserializationSchema<RowData>>) decodingFormat, |
| 112 | + tableDataType, |
| 113 | + dataTypeProjection, |
| 114 | + prefix, |
| 115 | + projectedFields, |
| 116 | + metadataSize); |
| 117 | + } else { |
| 118 | + return Decoder.projectAfterDeserializing( |
| 119 | + context, |
| 120 | + decodingFormat, |
| 121 | + tableDataType, |
| 122 | + dataTypeProjection, |
| 123 | + prefix, |
| 124 | + projectedFields, |
| 125 | + metadataSize); |
| 126 | + } |
| 127 | + } |
| 128 | + } |
| 129 | + |
| 130 | + /** @return a {@link DeserializationSchema} or null. */ |
| 131 | + @Nullable |
| 132 | + public DeserializationSchema<RowData> getDeserializationSchema() { |
| 133 | + return deserializationSchema; |
| 134 | + } |
| 135 | + |
| 136 | + /** @return a {@link Projector}. */ |
| 137 | + public Projector getProjector() { |
| 138 | + return projector; |
| 139 | + } |
| 140 | + |
| 141 | + private static Decoder noDeserializationOrProjection() { |
| 142 | + return new Decoder(null, new ProjectorImpl(Map.of())); |
| 143 | + } |
| 144 | + |
| 145 | + private static DataType toDataType( |
| 146 | + final DataType tableDataType, |
| 147 | + final int[] dataTypeProjection, |
| 148 | + final @Nullable String prefix) { |
| 149 | + final DataType temp = Projection.of(dataTypeProjection).project(tableDataType); |
| 150 | + return Optional.ofNullable(prefix) |
| 151 | + .map(s -> DataTypeUtils.stripRowPrefix(temp, s)) |
| 152 | + .orElse(temp); |
| 153 | + } |
| 154 | + |
| 155 | + private static Map<Integer, Integer> tableToDeserializedTopLevelPos( |
| 156 | + final int[] dataTypeProjection) { |
| 157 | + final HashMap<Integer, Integer> tableToDeserializedPos = new HashMap<>(); |
| 158 | + for (int i = 0; i < dataTypeProjection.length; i++) { |
| 159 | + tableToDeserializedPos.put(dataTypeProjection[i], i); |
| 160 | + } |
| 161 | + return tableToDeserializedPos; |
| 162 | + } |
| 163 | + |
| 164 | + private static int[] copyArray(final int[] arr) { |
| 165 | + return Arrays.copyOf(arr, arr.length); |
| 166 | + } |
| 167 | + |
| 168 | + private static void addMetadataProjections( |
| 169 | + final int deserializedSize, |
| 170 | + final int physicalSize, |
| 171 | + final int metadataSize, |
| 172 | + final Map<List<Integer>, Integer> deserializedToProducedPos) { |
| 173 | + for (int i = 0; i < metadataSize; i++) { |
| 174 | + // metadata is always added to the end of the deserialized row by the DecodingFormat |
| 175 | + final int deserializedPos = deserializedSize + i; |
| 176 | + // we need to always add metadata to the end of the produced row |
| 177 | + final int producePos = physicalSize + i; |
| 178 | + deserializedToProducedPos.put(List.of(deserializedPos), producePos); |
| 179 | + } |
| 180 | + } |
| 181 | + |
| 182 | + /** |
| 183 | + * This method generates a {@link Decoder} which pushes projections down directly into the |
| 184 | + * {@link ProjectableDecodingFormat} which takes care of projecting the fields during the |
| 185 | + * deserialization process itself. |
| 186 | + */ |
| 187 | + private static Decoder projectInsideDeserializer( |
| 188 | + final Context context, |
| 189 | + final ProjectableDecodingFormat<DeserializationSchema<RowData>> |
| 190 | + projectableDecodingFormat, |
| 191 | + final DataType tableDataType, |
| 192 | + final int[] dataTypeProjection, |
| 193 | + final @Nullable String prefix, |
| 194 | + final int[][] projectedFields, |
| 195 | + final int metadataSize) { |
| 196 | + final Map<Integer, Integer> tableToDeserializedTopLevelPos = |
| 197 | + tableToDeserializedTopLevelPos(dataTypeProjection); |
| 198 | + |
| 199 | + final List<int[]> deserializerProjectedFields = new ArrayList<>(); |
| 200 | + final Map<List<Integer>, Integer> deserializedToProducedPos = new HashMap<>(); |
| 201 | + for (int producedPos = 0; producedPos < projectedFields.length; producedPos++) { |
| 202 | + final int[] tablePos = projectedFields[producedPos]; |
| 203 | + final int tableTopLevelPos = tablePos[0]; |
| 204 | + |
| 205 | + final Integer dataTypeTopLevelPos = |
| 206 | + tableToDeserializedTopLevelPos.get(tableTopLevelPos); |
| 207 | + if (dataTypeTopLevelPos != null) { |
| 208 | + final int[] dataTypePos = copyArray(tablePos); |
| 209 | + dataTypePos[0] = dataTypeTopLevelPos; |
| 210 | + |
| 211 | + deserializerProjectedFields.add(dataTypePos); |
| 212 | + |
| 213 | + final int deserializedPos = deserializerProjectedFields.size() - 1; |
| 214 | + deserializedToProducedPos.put(List.of(deserializedPos), producedPos); |
| 215 | + } |
| 216 | + } |
| 217 | + |
| 218 | + addMetadataProjections( |
| 219 | + deserializerProjectedFields.size(), |
| 220 | + projectedFields.length, |
| 221 | + metadataSize, |
| 222 | + deserializedToProducedPos); |
| 223 | + |
| 224 | + return new Decoder( |
| 225 | + projectableDecodingFormat.createRuntimeDecoder( |
| 226 | + context, |
| 227 | + toDataType(tableDataType, dataTypeProjection, prefix), |
| 228 | + deserializerProjectedFields.toArray( |
| 229 | + new int[deserializerProjectedFields.size()][])), |
| 230 | + new ProjectorImpl(deserializedToProducedPos)); |
| 231 | + } |
| 232 | + |
| 233 | + /** |
| 234 | + * This method generates a {@link Decoder} which deserializes the data fully using the {@link |
| 235 | + * DecodingFormat} and then applies any projections afterward. |
| 236 | + */ |
| 237 | + private static Decoder projectAfterDeserializing( |
| 238 | + final Context context, |
| 239 | + final DecodingFormat<DeserializationSchema<RowData>> decodingFormat, |
| 240 | + final DataType tableDataType, |
| 241 | + final int[] dataTypeProjection, |
| 242 | + final @Nullable String prefix, |
| 243 | + final int[][] projectedFields, |
| 244 | + final int metadataSize) { |
| 245 | + final DataType dataType = toDataType(tableDataType, dataTypeProjection, prefix); |
| 246 | + final Map<Integer, Integer> tableToDeserializedTopLevelPos = |
| 247 | + tableToDeserializedTopLevelPos(dataTypeProjection); |
| 248 | + |
| 249 | + final Map<List<Integer>, Integer> deserializedToProducedPos = new HashMap<>(); |
| 250 | + for (int producedPos = 0; producedPos < projectedFields.length; producedPos++) { |
| 251 | + final int[] tablePos = projectedFields[producedPos]; |
| 252 | + int tableTopLevelPos = tablePos[0]; |
| 253 | + |
| 254 | + final Integer deserializedTopLevelPos = |
| 255 | + tableToDeserializedTopLevelPos.get(tableTopLevelPos); |
| 256 | + if (deserializedTopLevelPos != null) { |
| 257 | + final int[] deserializedPos = copyArray(tablePos); |
| 258 | + deserializedPos[0] = deserializedTopLevelPos; |
| 259 | + |
| 260 | + deserializedToProducedPos.put( |
| 261 | + Arrays.stream(deserializedPos) |
| 262 | + .boxed() |
| 263 | + .collect(Collectors.toUnmodifiableList()), |
| 264 | + producedPos); |
| 265 | + } |
| 266 | + } |
| 267 | + |
| 268 | + addMetadataProjections( |
| 269 | + dataTypeProjection.length, |
| 270 | + projectedFields.length, |
| 271 | + metadataSize, |
| 272 | + deserializedToProducedPos); |
| 273 | + |
| 274 | + return new Decoder( |
| 275 | + decodingFormat.createRuntimeDecoder(context, dataType), |
| 276 | + new ProjectorImpl(deserializedToProducedPos)); |
| 277 | + } |
| 278 | + |
| 279 | + /** Projects fields from the deserialized row to their positions in the final produced row. */ |
| 280 | + @Internal |
| 281 | + public interface Projector extends Serializable { |
| 282 | + /** Returns true if {@link #project} will not project any fields. */ |
| 283 | + boolean isEmptyProjection(); |
| 284 | + |
| 285 | + /** |
| 286 | + * Returns true if deserialized positions are different from the final produced row |
| 287 | + * positions. |
| 288 | + */ |
| 289 | + boolean isProjectionNeeded(); |
| 290 | + |
| 291 | + /** Copies fields from the deserialized row to their final positions in the produced row. */ |
| 292 | + void project(final RowData deserialized, final GenericRowData producedRow); |
| 293 | + } |
| 294 | + |
| 295 | + private static class ProjectorImpl implements Projector { |
| 296 | + |
| 297 | + private final Map<List<Integer>, Integer> deserializedToProducedPos; |
| 298 | + private final boolean isProjectionNeeded; |
| 299 | + |
| 300 | + ProjectorImpl(final Map<List<Integer>, Integer> deserializedToProducedPos) { |
| 301 | + this.deserializedToProducedPos = deserializedToProducedPos; |
| 302 | + this.isProjectionNeeded = |
| 303 | + !deserializedToProducedPos.entrySet().stream() |
| 304 | + .allMatch( |
| 305 | + entry -> { |
| 306 | + final List<Integer> deserializedPos = entry.getKey(); |
| 307 | + final List<Integer> producedPos = List.of(entry.getValue()); |
| 308 | + return Objects.equals(producedPos, deserializedPos); |
| 309 | + }); |
| 310 | + } |
| 311 | + |
| 312 | + @Override |
| 313 | + public boolean isEmptyProjection() { |
| 314 | + return deserializedToProducedPos.isEmpty(); |
| 315 | + } |
| 316 | + |
| 317 | + @Override |
| 318 | + public boolean isProjectionNeeded() { |
| 319 | + return isProjectionNeeded; |
| 320 | + } |
| 321 | + |
| 322 | + @Override |
| 323 | + public void project(final RowData deserialized, final GenericRowData producedRow) { |
| 324 | + this.deserializedToProducedPos.forEach( |
| 325 | + (deserializedPos, targetPos) -> { |
| 326 | + Object value = deserialized; |
| 327 | + for (final Integer i : deserializedPos) { |
| 328 | + value = ((GenericRowData) value).getField(i); |
| 329 | + } |
| 330 | + producedRow.setField(targetPos, value); |
| 331 | + }); |
| 332 | + } |
| 333 | + } |
| 334 | +} |
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