Redis methods and application examples for implementing asynchronous queues

Redis is a high-performance memory-based key-value storage database. It not only supports storing key-value pairs, but also supports some complex data structures, such as List, Set, Sorted Set, and Hash. The List data structure is very suitable as a data structure for asynchronous queues because it supports inserting and deleting elements at both ends. This article will introduce how to use Redis to implement asynchronous queues and give an application example.

1. How Redis implements asynchronous queues

Although List in Redis supports inserting and deleting elements at both ends, due to its special implementation, it cannot guarantee that all operations will be It is O(1) complexity. For example, if there are many elements in a List, then when deleting elements, you need to traverse the entire List to search, and the time complexity will become O(N). Therefore, when implementing an asynchronous queue, you need to pay attention to the following points:

1. Use the LPUSH and BRPOP commands

When implementing an asynchronous queue, we should try to avoid using LPOP and RPUSH command, instead use LPUSH and BRPOP commands. Because the LPOP and RPUSH commands insert and delete elements at both ends of the List, when there are many elements in the List, each operation needs to traverse the entire List, which is relatively inefficient; while the LPUSH and BRPOP commands use Redis The blocking feature is implemented. When the List is empty, the BRPOP command waits until there are elements in the List, and then returns the popped elements. This avoids traversing the entire List and greatly improves efficiency.

2. Set an appropriate timeout period

When using the BRPOP command, you need to set an appropriate timeout period to prevent the program from blocking all the time. Generally speaking, you can set a relatively short timeout, such as 1 second, so that the program can quickly detect whether new elements are added. At the same time, it is also necessary to note that setting the timeout period too short may cause the BRPOP command to be executed frequently and increase the burden on the Redis server.

3. Use multiple Lists

In order to improve concurrency performance, you can use multiple Lists, each List is responsible for storing a part of the tasks. Different tasks can be placed in different Lists to improve the effect of data sharding. At the same time, each List can also have an independent consumer thread, which can be executed in parallel when consuming tasks, thereby improving the concurrency performance of the entire system.

2. Application example of Redis asynchronous queue

Below we give an application example using Redis asynchronous queue: used to send SMS verification codes. In this application, we can divide the SMS verification codes to be sent into multiple lists according to mobile phone numbers, and then start a consumer thread for each List to send SMS messages. The specific implementation process is as follows:

1. Create Redis connection

Use Java language to connect to the Redis server, the code is as follows:

Jedis jedis = new Jedis("localhost", 6379);

2. Add task

Add the SMS verification code to be sent to the corresponding List. The code is as follows:

jedis.lpush(mobile, code);

where mobile is the mobile phone number and code is the verification code.

3. Consumption Task

Start a consumer thread for each List to send SMS messages. The code is as follows:

new Thread(new SmsSender(jedis, mobile)).start();

Among them, the SmsSender class is used for sending SMS, the constructor parameter jedis is used to connect to the Redis server, and mobile is used to specify the List that needs to be processed.

4. Consumer thread implementation

The consumer thread takes out the verification code that needs to be sent from the List through the BRPOP command, and then calls the third-party SMS sending interface to send it. The code is as follows:

public class SmsSender implements Runnable {
    private Jedis jedis;
    private String mobile;
    public SmsSender(Jedis jedis, String mobile) {
        this.jedis = jedis;
        this.mobile = mobile;
    }
    @Override
    public void run() {
        while (true) {
            List<String> codes = jedis.brpop(1, mobile);
            if (codes != null) {
                String code = codes.get(1);
                // 调用第三方短信接口发送验证码
                sendSms(mobile, code);
            }
        }
    }
}

The 1 second timeout can be adjusted according to actual needs.

Summary

This article introduces how to use Redis to implement asynchronous queues and gives a practical application example. When implementing asynchronous queues, you need to pay attention to using LPUSH and BRPOP commands, setting appropriate timeouts, and using multiple Lists to improve concurrency performance. By using Redis asynchronous queue, you can effectively improve system concurrency performance and improve user experience.

The above is the detailed content of Redis methods and application examples for implementing asynchronous queues. For more information, please follow other related articles on the PHP Chinese website!