Distributed cluster architecture scenario optimization solution ： Distributed ID Solution

Distributed ID Solution

Why do you need distributed ID( Global uniqueness in distributed cluster environment ID)

1、UUID( It can be used )

UUID Refer to Universally Unique Identifier, Translated into Chinese is Universal unique identification code

Produce repetition UUID Very low error rate , Therefore, there is no need to consider this problem .

import java.util.UUID;

public class UuidTest {
    

    public static void main(String[] args) {
    
        String uuid = UUID.randomUUID().toString();
        System.out.println(uuid);
    }
}

2、 Self augmentation of independent database ID

such as A The table is divided into A1 Table and A2 surface , Then we must not let A1 Table and A2 Tabular ID Self increasing , that ID How to get it ？

We can Create a separate Mysql database , Create a table in this database , This watch is ID Set to auto increment , other place It needs to be global and unique ID When , Just simulate this Mysql Simulate inserting a record into this table of the database , here ID Will be from increase , And then we can go through Mysql Of select last_insert_id() Get the self incrementing generated in the table just now ID.

such as , We created a database instance global_id_generator, A data table is created in it , Table structure is as follows Next ：

-- ----------------------------
-- Table structure for DISTRIBUTE_ID
-- ----------------------------
DROP TABLE IF EXISTS `DISTRIBUTE_ID`;
CREATE TABLE `DISTRIBUTE_ID` (
 `id` bigint(32) NOT NULL AUTO_INCREMENT COMMENT ' Primary key ',
 `createtime` datetime DEFAULT NULL,
 PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

In a distributed cluster environment, which application needs to obtain a globally unique distributed server ID When , You can use code to connect to this database instance , The implementation is as follows sql Sentence can be used .

insert into DISTRIBUTE_ID(createtime) values(NOW());
select LAST_INSERT_ID();

Be careful ：

1） there createtime Field has no practical meaning , Is to insert a piece of data so that it can increase itself id.

2） Use independent Mysql Instance generation is distributed id, It's possible , But the performance and reliability are not good enough , Because you need code to connect to the database to get id, Performance cannot be guaranteed , in addition mysql The database instance is down , Then you can't get points type id 了 .

3） Some developers will use it to generate distributed id Of mysql The database is designed as a cluster architecture , In fact, this way now Basically not , Because it's too much trouble .

3、SnowFlake Snowflake algorithm （ It can be used , recommend ）

The snowflake algorithm is Twitter A for generating distributed data is introduced ID The strategy of .

Snowflake algorithm is an algorithm , Based on this algorithm, we can generate ID, Generated ID It's a long type , So in Java In a long The type is 8 Bytes , Count it down 64bit, The following is a... Generated using the snowflake algorithm ID Binary form of ：

in addition , All Internet companies have also encapsulated some distributed based on the above scheme ID generator , For example, Didi tinyid（ Based on numbers Database implementation ）、 Baidu uidgenerator（ be based on SnowFlake） With meituan leaf（ Based on database and SnowFlake） etc. .

Algorithm code ：

/** *  Official launch ,Scala Programming language to achieve  * Java The elder used Java Language implements the snowflake algorithm  */
public class IdWorker{
    

    // Each of the following two 5 position , Add up to 10 Bit working machine id
    private long workerId;    // Work id
    private long datacenterId;   // data id
    //12 Bit's serial number 
    private long sequence;

    public IdWorker(long workerId, long datacenterId, long sequence){
    
        // sanity check for workerId
        if (workerId > maxWorkerId || workerId < 0) {
    
            throw new IllegalArgumentException(String.format("worker Id can't be greater than %d or less than 0",maxWorkerId));
        }
        if (datacenterId > maxDatacenterId || datacenterId < 0) {
    
            throw new IllegalArgumentException(String.format("datacenter Id can't be greater than %d or less than 0",maxDatacenterId));
        }
        System.out.printf("worker starting. timestamp left shift %d, datacenter id bits %d, worker id bits %d, sequence bits %d, workerid %d",
                timestampLeftShift, datacenterIdBits, workerIdBits, sequenceBits, workerId);

        this.workerId = workerId;
        this.datacenterId = datacenterId;
        this.sequence = sequence;
    }

    // Initial timestamp 
    private long twepoch = 1288834974657L;

    // The length is 5 position 
    private long workerIdBits = 5L;
    private long datacenterIdBits = 5L;
    // Maximum 
    private long maxWorkerId = -1L ^ (-1L << workerIdBits);
    private long maxDatacenterId = -1L ^ (-1L << datacenterIdBits);
    // Serial number id length 
    private long sequenceBits = 12L;
    // Maximum serial number 
    private long sequenceMask = -1L ^ (-1L << sequenceBits);
    
    // Work id The number of digits that need to be shifted left ,12 position 
    private long workerIdShift = sequenceBits;
    // data id You need to shift the number of digits to the left  12+5=17 position 
    private long datacenterIdShift = sequenceBits + workerIdBits;
    // Timestamps need to be shifted to the left  12+5+5=22 position 
    private long timestampLeftShift = sequenceBits + workerIdBits + datacenterIdBits;
    
    // Last time stamp , The initial value is negative 
    private long lastTimestamp = -1L;

    public long getWorkerId(){
    
        return workerId;
    }

    public long getDatacenterId(){
    
        return datacenterId;
    }

    public long getTimestamp(){
    
        return System.currentTimeMillis();
    }

     // next ID generating algorithm 
    public synchronized long nextId() {
    
        long timestamp = timeGen();

        // Get the current time stamp. If it is less than the last time stamp , Indicates that there is an exception in timestamp acquisition 
        if (timestamp < lastTimestamp) {
    
            System.err.printf("clock is moving backwards. Rejecting requests until %d.", lastTimestamp);
            throw new RuntimeException(String.format("Clock moved backwards. Refusing to generate id for %d milliseconds",
                    lastTimestamp - timestamp));
        }

        // Get the current time stamp if it is equal to the last time stamp 
        // explain ： Still in the same millisecond , Add... To the serial number 1; Otherwise, the serial number is assigned to 0, from 0 Start .
        if (lastTimestamp == timestamp) {
      // 0 - 4095
            sequence = (sequence + 1) & sequenceMask;
            if (sequence == 0) {
    
                timestamp = tilNextMillis(lastTimestamp);
            }
        } else {
    
            sequence = 0;
        }
        
        // Refresh last timestamp value 
        lastTimestamp = timestamp;

        /** *  Return results ： * (timestamp - twepoch) << timestampLeftShift)  Indicates that the initial timestamp is subtracted from the timestamp , Move the corresponding digit to the left  * (datacenterId << datacenterIdShift)  It means that the data will be id Move the corresponding digit to the left  * (workerId << workerIdShift)  I'm going to work id Move the corresponding digit to the left  * |  It's a bitwise OR operator , for example ：x | y, Only when x,y All for 0 It turns out to be 0, In other cases, the result is 1. *  Because only the values in the corresponding bits are meaningful , All the others are 0, So the values of each part are calculated  |  You can get the final stitched id */
        return ((timestamp - twepoch) << timestampLeftShift) |
                (datacenterId << datacenterIdShift) |
                (workerId << workerIdShift) |
                sequence;
    }

    // Get the timestamp , And compare with the last timestamp 
    private long tilNextMillis(long lastTimestamp) {
    
        long timestamp = timeGen();
        while (timestamp <= lastTimestamp) {
    
            timestamp = timeGen();
        }
        return timestamp;
    }

    // Get the system timestamp 
    private long timeGen(){
    
        return System.currentTimeMillis();
    }
    
    public static void main(String[] args) {
    
        IdWorker worker = new IdWorker(21,10,0);
        for (int i = 0; i < 100; i++) {
    
            System.out.println(worker.nextId());
        }
    }

}

4、 With the help of Redis Of Incr Command to get globally unique ID（ recommend ）

Redis Incr The order will key The value of the number stored in is increased by one . If key non-existent , that key The value of is initialized to 0 , And then execute INCR operation .

<key,value>

<id,>

.incr(id) 1 2 3 4

Redis install ：

• Download from the official website redis-3.2.10.tar.gz

• Upload to linux The server unzips tar -zxvf redis-3.2.10.tar.gz

• cd Unzip the file directory , For decompressed redis Compile

  make

• then cd Get into src Catalog , perform make install

• Modify the configuration file in the decompression directory redis.conf, Turn off protection mode

• stay src Execute under directory ./redis-server …/redis.conf start-up redis service

Java The code uses Jedis Client calls Reids Of incr Command to get a global id

• introduce jedis client jar

<dependency>
	<groupId>redis.clients</groupId>
	<artifactId>jedis</artifactId>
	<version>2.9.0</version>
</dependency>

• Java Code （ Here we are connecting single nodes , Also do not use connection pooling ）

import redis.clients.jedis.Jedis;

public class RedisGenerator {
    
    public static void main(String[] args) {
    
        Jedis jedis = new Jedis("192.168.2.3",6379);
        Long id = jedis.incr("id");//<id,0>
        System.out.println(id);
    }
}