Redis: the key technology for building a real-time push system
Redis: the key technology for building a real-time push system
With the development of the Internet and the advancement of intelligent technology, the importance of real-time push systems has become increasingly prominent. In the process of implementing the real-time push system, Redis (Remote Dictionary Server), as an in-memory database, provides important support for building an efficient real-time push system. This article will introduce the key technologies involved in building a real-time push system and provide specific code examples.
Redis is an open source NoSQL database that stores data based on memory and provides persistence functions. Its fast reading and writing capabilities and rich data structures make it an ideal choice for building real-time push systems. The following will introduce the key technologies and specific code examples of Redis in the real-time push system.
1. Publish and subscribe model
Redis provides a publish and subscribe (Pub/Sub) function, through which real-time push of messages can be achieved. The publisher publishes messages to the specified channel, and the subscriber receives the message in the subscribed channel and processes it accordingly. The following is a simple publish and subscribe code example:
Publisher:
const redis = require("redis"); const publisher = redis.createClient(); publisher.publish("channel1", "hello");
Subscriber:
const redis = require("redis"); const subscriber = redis.createClient(); subscriber.on("message", function (channel, message) { console.log("Receive message:", message); }); subscriber.subscribe("channel1");
Through the publish and subscribe model, real-time push of messages can be achieved, applicable Used in real-time chat, news push and other scenarios.
2. List structure
The list structure of Redis is very suitable for building a message queue, and the queuing and processing of messages can be realized through the list structure. The following is a simple code example using a list structure:
Message producer:
const redis = require("redis"); const client = redis.createClient(); client.lpush("messageQueue", "message1");
Message consumer:
const redis = require("redis"); const client = redis.createClient(); client.brpop("messageQueue", 0, function (err, value) { console.log("Receive message:", value[1]); });
Through the list structure, messages can be queued and Consumption is suitable for scenarios such as task scheduling and notification delivery.
3. Ordered Collection
Ordered collection is an important data structure in Redis. Functions such as real-time hot lists and rankings can be realized through ordered collections. The following is a simple code example using ordered collections:
Add leaderboard members:
const redis = require("redis"); const client = redis.createClient(); client.zadd("rankList", 100, "user1"); client.zadd("rankList", 90, "user2");
Get leaderboards:
const redis = require("redis"); const client = redis.createClient(); client.zrevrange("rankList", 0, 9, "withscores", function (err, members) { console.log("Rank list:", members); });
Through ordered collections, real-time can be achieved The ranking function is suitable for game rankings, hot topics and other scenarios.
To sum up, Redis, as an in-memory database, provides rich data structures and functions, providing important support for building a real-time push system. Through key technologies such as publish-subscribe model, list structure and ordered collection, an efficient real-time push system can be realized. In actual projects, developers can flexibly choose appropriate technologies and data structures based on actual needs, and use Redis to build a stable and efficient real-time push system.
We hope that the specific code examples provided in this article can help readers better understand the application of Redis in real-time push systems. We also hope that readers can learn and apply Redis in depth based on actual needs to build more powerful and Stable real-time push system.
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The core function of Redis is a high-performance in-memory data storage and processing system. 1) High-speed data access: Redis stores data in memory and provides microsecond-level read and write speed. 2) Rich data structure: supports strings, lists, collections, etc., and adapts to a variety of application scenarios. 3) Persistence: Persist data to disk through RDB and AOF. 4) Publish subscription: Can be used in message queues or real-time communication systems.

Redis supports a variety of data structures, including: 1. String, suitable for storing single-value data; 2. List, suitable for queues and stacks; 3. Set, used for storing non-duplicate data; 4. Ordered Set, suitable for ranking lists and priority queues; 5. Hash table, suitable for storing object or structured data.

Redis counter is a mechanism that uses Redis key-value pair storage to implement counting operations, including the following steps: creating counter keys, increasing counts, decreasing counts, resetting counts, and obtaining counts. The advantages of Redis counters include fast speed, high concurrency, durability and simplicity and ease of use. It can be used in scenarios such as user access counting, real-time metric tracking, game scores and rankings, and order processing counting.

Use the Redis command line tool (redis-cli) to manage and operate Redis through the following steps: Connect to the server, specify the address and port. Send commands to the server using the command name and parameters. Use the HELP command to view help information for a specific command. Use the QUIT command to exit the command line tool.

Redis cluster mode deploys Redis instances to multiple servers through sharding, improving scalability and availability. The construction steps are as follows: Create odd Redis instances with different ports; Create 3 sentinel instances, monitor Redis instances and failover; configure sentinel configuration files, add monitoring Redis instance information and failover settings; configure Redis instance configuration files, enable cluster mode and specify the cluster information file path; create nodes.conf file, containing information of each Redis instance; start the cluster, execute the create command to create a cluster and specify the number of replicas; log in to the cluster to execute the CLUSTER INFO command to verify the cluster status; make

To read a queue from Redis, you need to get the queue name, read the elements using the LPOP command, and process the empty queue. The specific steps are as follows: Get the queue name: name it with the prefix of "queue:" such as "queue:my-queue". Use the LPOP command: Eject the element from the head of the queue and return its value, such as LPOP queue:my-queue. Processing empty queues: If the queue is empty, LPOP returns nil, and you can check whether the queue exists before reading the element.

Use of zset in Redis cluster: zset is an ordered collection that associates elements with scores. Sharding strategy: a. Hash sharding: Distribute the hash value according to the zset key. b. Range sharding: divide into ranges according to element scores, and assign each range to different nodes. Read and write operations: a. Read operations: If the zset key belongs to the shard of the current node, it will be processed locally; otherwise, it will be routed to the corresponding shard. b. Write operation: Always routed to shards holding the zset key.

How to clear Redis data: Use the FLUSHALL command to clear all key values. Use the FLUSHDB command to clear the key value of the currently selected database. Use SELECT to switch databases, and then use FLUSHDB to clear multiple databases. Use the DEL command to delete a specific key. Use the redis-cli tool to clear the data.


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