flink-state-backends/flink-statebackend-rocksdb/src/main/java/org/apache/flink/contrib/streaming/state/RocksDBStateBackendFactory.java

/*
 * 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.flink.contrib.streaming.state;

import org.apache.flink.configuration.CheckpointingOptions;
import org.apache.flink.configuration.IllegalConfigurationException;
import org.apache.flink.configuration.ReadableConfig;
import org.apache.flink.runtime.state.StateBackendFactory;

import java.io.IOException;

/**
 * A factory that creates an {@link org.apache.flink.contrib.streaming.state.RocksDBStateBackend}
 * from a configuration.
 */
public class RocksDBStateBackendFactory implements StateBackendFactory<RocksDBStateBackend> {

    @Override
    public RocksDBStateBackend createFromConfig(ReadableConfig config, ClassLoader classLoader)
            throws IllegalConfigurationException, IOException {

        // we need to explicitly read the checkpoint directory here, because that
        // is a required constructor parameter
        final String checkpointDirURI = config.get(CheckpointingOptions.CHECKPOINTS_DIRECTORY);
        if (checkpointDirURI == null) {
            throw new IllegalConfigurationException(
                    "Cannot create the RocksDB state backend: The configuration does not specify the "
                            + "checkpoint directory '"
                            + CheckpointingOptions.CHECKPOINTS_DIRECTORY.key()
                            + '\'');
        }

        return new RocksDBStateBackend(checkpointDirURI).configure(config, classLoader);
    }
}