Node.js – retry_strategy Property in Redis

The retry_strategy is a function that receives objects as parameters including the retry attempt,total_retry_time that indicates the time passed after it was connected the last time, the error due to which the connection was lost, and the number of times_connected in total.

If a number is returned from this function, the next retry will take place after that time only in milliseconds and if you send a non-number, no further retry will take place.

Syntax

retry_strategy: funciton(options)

Example 1

Create a file with the name "retryStrategy.js" and copy the following code. After creating the file, use the command "node retryStrategy.js" to run this code as shown in the example below

// retry_strategy Property Demo Example

// Importing the redis module
const redis = require("redis");

// Creating redis client with retry_strategy
const client = redis.createClient({
   retry_strategy: function(options) {
      if (options.error && options.error.code === "ECONNREFUSED") {
         // If redis refuses the connection or is not able to connect
         return new Error("The server refused the connection");
      }
      if (options.total_retry_time > 1000 * 60 * 60) {
         // End reconnection after the specified time limit
         return new Error("Retry time exhausted");
      }
      if (options.attempt > 10) {
         // End reconnecting with built in error
         return undefined;
      }
      // reconnect after
      return Math.min(options.attempt * 100, 3000);
   },
});

console.log("Connection created successfully !")
client.set("key", "TutorialsPoint");

// This will return a JavaScript String
client.get("key", function(err, reply) { 
   console.log(reply);
});

Output

Connection created successfully!
TutorialsPoint

The following error is thrown in case it is not able to establish a connection with Redis.

Error: Redis connection in broken state: retry aborted.
   at RedisClient.connection_gone
(/home/redis/node_modules/redis/index.js:569:30)
   at RedisClient.on_error
(/home/redis/node_modules/redis/index.js:346:10)
   at Socket.<anonymous>
(/home/redis/node_modules/redis/index.js:223:14)
   at Socket.emit (events.js:198:13)
   at emitErrorNT (internal/streams/destroy.js:91:8)
   at emitErrorAndCloseNT (internal/streams/destroy.js:59:3)
   at process._tickCallback
(internal/process/next_tick.js:63:19)

Mayank Agarwal

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Updated on: 24-Nov-2021

3K+ Views

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