[HUDI-3607] Support backend switch in HoodieFlinkStreamer (#5032)

* [HUDI-3607] Support backend switch in HoodieFlinkStreamer

* [HUDI-3607] Support backend switch in HoodieFlinkStreamer
1. checkstyle fix

* [HUDI-3607] Support backend switch in HoodieFlinkStreamer
1. change the msg

hudi-flink/pom.xml

@@ -174,6 +174,12 @@
       <version>${flink.version}</version>
       <scope>provided</scope>
     </dependency>
+    <dependency>
+      <groupId>org.apache.flink</groupId>
+      <artifactId>flink-statebackend-rocksdb_${scala.binary.version}</artifactId>
+      <version>${flink.version}</version>
+      <scope>provided</scope>
+    </dependency>
 
     <dependency>
       <groupId>org.apache.parquet</groupId>

hudi-flink/src/main/java/org/apache/hudi/streamer/FlinkStreamerConfig.java

@@ -18,6 +18,8 @@
 
 package org.apache.hudi.streamer;
 
+import org.apache.flink.runtime.state.StateBackend;
+import org.apache.flink.runtime.state.hashmap.HashMapStateBackend;
 import org.apache.hudi.client.utils.OperationConverter;
 import org.apache.hudi.common.model.OverwriteWithLatestAvroPayload;
 import org.apache.hudi.common.model.WriteOperationType;
@@ -25,6 +27,7 @@ import org.apache.hudi.common.util.StringUtils;
 import org.apache.hudi.configuration.FlinkOptions;
 import org.apache.hudi.hive.SlashEncodedDayPartitionValueExtractor;
 import org.apache.hudi.keygen.constant.KeyGeneratorType;
+import org.apache.hudi.util.FlinkStateBackendConverter;
 import org.apache.hudi.util.StreamerUtil;
 
 import com.beust.jcommander.Parameter;
@@ -53,6 +56,10 @@ public class FlinkStreamerConfig extends Configuration {
   @Parameter(names = {"--flink-checkpoint-path"}, description = "Flink checkpoint path.")
   public String flinkCheckPointPath;
 
+  @Parameter(names = {"--flink-state-backend-type"}, description = "Flink state backend type, support only hashmap and rocksdb by now,"
+          + " default hashmap.", converter = FlinkStateBackendConverter.class)
+  public StateBackend stateBackend = new HashMapStateBackend();
+
   @Parameter(names = {"--instant-retry-times"}, description = "Times to retry when latest instant has not completed.")
   public String instantRetryTimes = "10";
 

hudi-flink/src/main/java/org/apache/hudi/streamer/HoodieFlinkStreamer.java

@@ -32,7 +32,6 @@ import com.beust.jcommander.JCommander;
 import org.apache.flink.configuration.Configuration;
 import org.apache.flink.formats.common.TimestampFormat;
 import org.apache.flink.formats.json.JsonRowDataDeserializationSchema;
-import org.apache.flink.runtime.state.filesystem.FsStateBackend;
 import org.apache.flink.streaming.api.datastream.DataStream;
 import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
 import org.apache.flink.streaming.connectors.kafka.FlinkKafkaConsumer;
@@ -61,8 +60,9 @@ public class HoodieFlinkStreamer {
     // There can only be one checkpoint at one time.
     env.getCheckpointConfig().setMaxConcurrentCheckpoints(1);
 
+    env.setStateBackend(cfg.stateBackend);
     if (cfg.flinkCheckPointPath != null) {
-      env.setStateBackend(new FsStateBackend(cfg.flinkCheckPointPath));
+      env.getCheckpointConfig().setCheckpointStorage(cfg.flinkCheckPointPath);
     }
 
     TypedProperties kafkaProps = DFSPropertiesConfiguration.getGlobalProps();

hudi-flink/src/main/java/org/apache/hudi/util/FlinkStateBackendConverter.java

@@ -0,0 +1,41 @@
+/*
+ * 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.hudi.util;
+
+import com.beust.jcommander.IStringConverter;
+import com.beust.jcommander.ParameterException;
+import org.apache.flink.contrib.streaming.state.EmbeddedRocksDBStateBackend;
+import org.apache.flink.runtime.state.StateBackend;
+import org.apache.flink.runtime.state.hashmap.HashMapStateBackend;
+import org.apache.hudi.exception.HoodieException;
+
+/**
+ * Converter that converts a string into Flink StateBackend.
+ */
+public class FlinkStateBackendConverter implements IStringConverter<StateBackend> {
+  @Override
+  public StateBackend convert(String value) throws ParameterException {
+    switch (value) {
+      case "hashmap" : return new HashMapStateBackend();
+      case "rocksdb" : return new EmbeddedRocksDBStateBackend();
+      default:
+        throw new HoodieException(String.format("Unknown flink state backend %s.", value));
+    }
+  }
+}