2.1 辅助源码

2.1.1 持久化源码

Leader和Follower中的数据会在内存和磁盘中各保存一份。所以需要将内存中的数据持久化到磁盘中。

在org.apache.zookeeper.server.persistence包下的相关类都是序列化相关的代码。

1）快照

public interface SnapShot {
    
    // 反序列化方法
    long deserialize(DataTree dt, Map<Long, Integer> sessions) 
        throws IOException;
    
    // 序列化方法
    void serialize(DataTree dt, Map<Long, Integer> sessions, 
            File name) 
        throws IOException;
    
    /
     * find the most recent snapshot file
	 * 查找最近的快照文件
     */
    File findMostRecentSnapshot() throws IOException;
    
    // 释放资源
    void close() throws IOException;
}

2）操作日志

public interface TxnLog {

    // 设置服务状态
    void setServerStats(ServerStats serverStats);
    
    // 滚动日志
    void rollLog() throws IOException;
	
    // 追加
    boolean append(TxnHeader hdr, Record r) throws IOException;

    // 读取数据
    TxnIterator read(long zxid) throws IOException;
    
    // 获取最后一个zxid
    long getLastLoggedZxid() throws IOException;
    
    // 删除日志
    boolean truncate(long zxid) throws IOException;
    
    // 获取DbId
    long getDbId() throws IOException;
    
    // 提交
    void commit() throws IOException;

    // 日志同步时间
    long getTxnLogSyncElapsedTime();
   
    // 关闭日志
    void close() throws IOException;
	
    // 读取日志的接口
    public interface TxnIterator {
	
        // 获取头信息
        TxnHeader getHeader();
        
        // 获取传输的内容
        Record getTxn();
     
        // 下一条记录
        boolean next() throws IOException;
        
        // 关闭资源
        void close() throws IOException;
        
        // 获取存储的大小
        long getStorageSize() throws IOException;
    }
}

3）处理持久化的核心类

2.1.2 序列化源码

zookeeper-jute代码是关于Zookeeper序列化相关源码

1）序列化和反序列化方法

public interface Record {
    // 序列化方法
    public void serialize(OutputArchive archive, String tag)
        throws IOException;

    // 反序列化方法
    public void deserialize(InputArchive archive, String tag)
        throws IOException;
}

2）迭代

public interface Index {
    // 结束
    public boolean done();
    // 下一个
    public void incr();
}

3）序列化支持的数据类型

/
 * Interface that alll the serializers have to implement.
 *
 */
public interface OutputArchive {
    public void writeByte(byte b, String tag) throws IOException;
    public void writeBool(boolean b, String tag) throws IOException;
    public void writeInt(int i, String tag) throws IOException;
    public void writeLong(long l, String tag) throws IOException;
    public void writeFloat(float f, String tag) throws IOException;
    public void writeDouble(double d, String tag) throws IOException;
    public void writeString(String s, String tag) throws IOException;
    public void writeBuffer(byte buf[], String tag)
        throws IOException;
    public void writeRecord(Record r, String tag) throws IOException;
    public void startRecord(Record r, String tag) throws IOException;
    public void endRecord(Record r, String tag) throws IOException;
    public void startVector(List<?> v, String tag) throws IOException;
    public void endVector(List<?> v, String tag) throws IOException;
    public void startMap(TreeMap<?,?> v, String tag) throws IOException;
    public void endMap(TreeMap<?,?> v, String tag) throws IOException;
}

4）反序列化支持的数据类型

/
 * Interface that all the Deserializers have to implement.
 *
 */
public interface InputArchive {
    public byte readByte(String tag) throws IOException;
    public boolean readBool(String tag) throws IOException;
    public int readInt(String tag) throws IOException;
    public long readLong(String tag) throws IOException;
    public float readFloat(String tag) throws IOException;
    public double readDouble(String tag) throws IOException;
    public String readString(String tag) throws IOException;
    public byte[] readBuffer(String tag) throws IOException;
    public void readRecord(Record r, String tag) throws IOException;
    public void startRecord(String tag) throws IOException;
    public void endRecord(String tag) throws IOException;
    public Index startVector(String tag) throws IOException;
    public void endVector(String tag) throws IOException;
    public Index startMap(String tag) throws IOException;
    public void endMap(String tag) throws IOException;
}