PHP method to implement automatic switching of Redis master-slave replication

Redis is a very popular key-value storage database that plays a vital role in modern web applications. In order to ensure the high availability and stability of Redis, it is usually necessary to use master-slave replication technology. At the same time, since the master node needs to automatically switch to the backup node when it fails, the replication cluster has the ability to self-heal. The following describes how PHP implements automatic switching of Redis master-slave replication.

1. Introduction to Redis master-slave replication

Redis master-slave replication is a technology that copies data from one Redis server to multiple slave servers to achieve distributed reading and automatic failover. . The master node receives write operations, while the slave node can only accept read requests and replicates updates from the master node asynchronously. When the primary node fails, it will automatically switch to the backup node to ensure high availability.

2. PHP implements Redis master-slave replication

In PHP, we can use the Redis extension package to quickly implement the automatic switching function of Redis master-slave replication. Here we take PHP 7.0.0 version as an example. First, install the Redis extension package in the Linux environment:

sudo pecl install redis

Or download and install manually:

wget https://github.com/phpredis/phpredis/archive/4.1.1.tar.gz
tar xvzf 4.1.1.tar.gz
cd phpredis-4.1.1/
phpize
./configure
make
sudo make install

After the installation is complete, you can add the following configuration to php.ini to enable the Redis extension package:

extension=redis.so

Next, we use the following PHP code to implement the automatic switching method of Redis master-slave replication:

//定义主从节点的参数
$redisMaster = [
    'host' => '127.0.0.1',
    'port' => '6379'
];
$redisSlave1 = [
    'host' => '127.0.0.1',
    'port' => '6380'
];
$redisSlave2 = [
    'host' => '127.0.0.1',
    'port' => '6381'
];

//创建主节点连接并设置自动重连
$redis = new Redis();
$redis->pconnect($redisMaster['host'], $redisMaster['port']);
$redis->setOption(Redis::OPT_AUTO_RECONNECT, true);

//创建从节点连接并设置自动重连
$redisSlave1 = new Redis();
$redisSlave1->pconnect($redisSlave1['host'], $redisSlave1['port']);
$redisSlave1->setOption(Redis::OPT_AUTO_RECONNECT, true);

$redisSlave2 = new Redis();
$redisSlave2->pconnect($redisSlave2['host'], $redisSlave2['port']);
$redisSlave2->setOption(Redis::OPT_AUTO_RECONNECT, true);

//测试连接是否正常
if(!$redis->ping()){
    //如果主节点出现故障，自动切换到备用节点
    if(!$redisSlave1->ping() && !$redisSlave2->ping()){
        //如果备用节点1和备用节点2都无法连接，则抛出异常
        throw new Exception('Redis主备节点全部宕机');
    }elseif($redisSlave1->ping()){
        $redis = $redisSlave1;
    }elseif($redisSlave2->ping()){
        $redis = $redisSlave2;
    }
}

//使用Redis主节点进行数据操作
$redis->set('foo', 'bar');
$value = $redis->get('foo');
echo $value;

In the above code, we first define the parameters of three Redis nodes, including the master node and Two spare nodes. Then the master node and two slave node connections were created respectively, and the automatic reconnection option was set. If the primary node connection fails, it will automatically switch to backup node 1 or 2. If both standby node 1 and standby node 2 fail to connect, an exception will be thrown. Finally, use the Redis master node for data operations.

3. Summary

Redis master-slave replication is an effective high-availability technology that can ensure that the Redis database can self-repair and keep running under faults and abnormal conditions. In PHP, you can use the Redis extension to quickly implement the automatic switching function of Redis master-slave replication. Through the above methods, the high availability and stability of Redis can be easily achieved, providing more robust basic services for modern web applications.

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