从flink checkpoint中解析出iceberg的snapshot ID

在使用flink sql 读取 iceberg 的快照的时候发现一个问题。就是我不知道当前消费到哪个快照ID。同时flink 1.19其实已经取消了checkpoint数据的解析工具。所以我打算自己实现一个java程序来解析flink checkpoint。其中主要是用的对象是flink-core自身的CheckpointMetadata对象。下面是完整的代码和依赖：

    <dependencies>
        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-core</artifactId>
            <version>1.19.3</version>
<!--            <scope>provided</scope>-->
        </dependency>
        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-runtime</artifactId>
            <version>1.19.3</version>
<!--            <scope>provided</scope>-->
        </dependency>
        <dependency>
            <groupId>org.apache.iceberg</groupId>
            <artifactId>iceberg-flink-1.19</artifactId>
            <version>1.6.1</version>
        </dependency>
    </dependencies>

下面是具体的代码：

package com.demo.flink;

import org.apache.flink.api.common.typeutils.base.LongSerializer;
import org.apache.flink.core.fs.FSDataInputStream;
import org.apache.flink.core.memory.DataInputDeserializer;
import org.apache.flink.runtime.checkpoint.Checkpoints;
import org.apache.flink.runtime.checkpoint.OperatorState;
import org.apache.flink.runtime.checkpoint.OperatorSubtaskState;
import org.apache.flink.runtime.checkpoint.StateObjectCollection;
import org.apache.flink.runtime.checkpoint.metadata.CheckpointMetadata;
import org.apache.flink.runtime.state.*;

import java.io.*;
import java.util.Map;


public class CheckpointMetadataParser {
    public static void main(String[] args) throws IOException {
        //  读取元数据文件
        File f=new File("src/main/resources/_metadata");
        FileInputStream fis=new FileInputStream(f);
        BufferedInputStream bis = new BufferedInputStream(fis);
        DataInputStream dis = new DataInputStream(bis);


        // 通过 Flink 的 Checkpoints 类解析元数据文件
        CheckpointMetadata savepoint = Checkpoints.loadCheckpointMetadata(dis,
                CheckpointMetadataParser.class.getClassLoader(), f.getAbsolutePath());
        // 打印当前的 CheckpointId
        System.out.println("CheckpointId：" + savepoint.getCheckpointId());

        for(OperatorState operatorState : savepoint.getOperatorStates()) {
            Map<Integer, OperatorSubtaskState> subtaskStateMap = operatorState.getSubtaskStates();
            for(Integer subtaskId : subtaskStateMap.keySet()) {
                OperatorSubtaskState subtaskState = subtaskStateMap.get(subtaskId);
                StateObjectCollection<OperatorStateHandle> managedOperatorState = subtaskState.getManagedOperatorState();
                if(managedOperatorState!=null) {
                    for(OperatorStateHandle stateHandle: managedOperatorState){
                        if(stateHandle.getStateNameToPartitionOffsets().containsKey("snapshot-id-state")){
                            System.out.println("Found snapshot-id-state in: " + stateHandle);

                            // 获取偏移量状态
                            OperatorStateHandle.StateMetaInfo metaInfo = stateHandle.getStateNameToPartitionOffsets().get("snapshot-id-state");
                            long offset = metaInfo.getOffsets()[0];
                            System.out.println("State offset: " + offset);

                            // 读取状态偏移量
                            try(FSDataInputStream in = stateHandle.getDelegateStateHandle().openInputStream()){
                                in.seek(offset);
                                byte[] data = new byte[8];
                                in.read(data);
                                DataInputDeserializer dataInput = new DataInputDeserializer(data);
                                // 使用 LongSerializer反序列化
                                LongSerializer serializer = LongSerializer.INSTANCE;
                                Long snapshotId = serializer.deserialize(dataInput);

                                System.out.println("Snapshot ID: " + snapshotId);
                            }
                        }
                    }
                }
            }
        }
    }
}