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https://github.com/jaredwray/memcache

Nodejs Memcache Driver
https://github.com/jaredwray/memcache

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Nodejs Memcache Driver

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README 

          
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# Memcache

Nodejs Memcache Client



# Table of Contents



- [Getting Started](#getting-started)

  - [Installation](#installation)

  - [Basic Usage](#basic-usage)

  - [Custom Connection](#custom-connection)

- [API](#api)

  - [Constructor](#constructor)

  - [Properties](#properties)

  - [Connection Management](#connection-management)

  - [Node Management](#node-management)

  - [Data Storage Operations](#data-storage-operations)

  - [String Modification Operations](#string-modification-operations)

  - [Deletion & Expiration](#deletion--expiration)

  - [Numeric Operations](#numeric-operations)

  - [Server Management & Statistics](#server-management--statistics)

  - [Validation](#validation)

  - [Helper Functions](#helper-functions)

- [Hooks and Events](#hooks-and-events)

  - [Events](#events)

  - [Available Events](#available-events)

  - [Hooks](#hooks)

  - [Available Hooks](#available-hooks)

    - [get(key)](#getkey)

    - [set(key, value, exptime?, flags?)](#setkey-value-exptime-flags)

    - [gets(keys[])](#getskeys)

    - [add(key, value, exptime?, flags?)](#addkey-value-exptime-flags)

    - [replace(key, value, exptime?, flags?)](#replacekey-value-exptime-flags)

    - [append(key, value)](#appendkey-value)

    - [prepend(key, value)](#prependkey-value)

    - [delete(key)](#deletekey)

    - [incr(key, value?)](#incrkey-value)

    - [decr(key, value?)](#decrkey-value)

    - [touch(key, exptime)](#touchkey-exptime)

  - [Hook Examples](#hook-examples)

- [Distribution Algorithms](#distribution-algorithms)

  - [KetamaHash (Default)](#ketamahash-default)

  - [ModulaHash](#modulahash)

  - [Choosing an Algorithm](#choosing-an-algorithm)

- [Retry Configuration](#retry-configuration)

  - [Basic Retry Setup](#basic-retry-setup)

  - [Backoff Strategies](#backoff-strategies)

  - [Idempotent Safety](#idempotent-safety)

  - [Methods Without Retry Support](#methods-without-retry-support)

- [SASL Authentication](#sasl-authentication)

  - [Enabling SASL Authentication](#enabling-sasl-authentication)

  - [SASL Options](#sasl-options)

  - [Per-Node SASL Configuration](#per-node-sasl-configuration)

  - [Authentication Events](#authentication-events)

  - [Server Configuration](#server-configuration)

- [Auto Discovery](#auto-discovery)

  - [Enabling Auto Discovery](#enabling-auto-discovery)

  - [Auto Discovery Options](#auto-discovery-options)

  - [Auto Discovery Events](#auto-discovery-events)

  - [Legacy Command Support](#legacy-command-support)

- [IPv6 Support](#ipv6-support)

- [Contributing](#contributing)

- [License and Copyright](#license-and-copyright)



# Getting Started



## Installation



```bash

npm install memcache

```



or with pnpm:



```bash

pnpm add memcache

```



## Basic Usage



```javascript

import { Memcache } from 'memcache';



// Create a new client

const client = new Memcache();



// Set a value

await client.set('mykey', 'Hello, Memcache!');



// Get a value

const value = await client.get('mykey');

console.log(value); // ['Hello, Memcache!']



// Delete a value

await client.delete('mykey');



// Close the connection

await client.quit();

```



You can also just pass in the `uri` into the constructor



```javascript

// Single node as string

const client = new Memcache('localhost:11211');



// Single node with protocol

const client = new Memcache('memcache://192.168.1.100:11211');



// Multiple nodes with options

const client = new Memcache({

  nodes: ['localhost:11211', 'server2:11211'],

  timeout: 10000

});

```



You can specify multiple Memcache nodes by passing an array of connection strings:



```javascript

import { Memcache } from 'memcache';



// Create a client with multiple nodes

const client = new Memcache({

  nodes: ['localhost:11211', '192.168.1.100:11211', 'memcache://192.168.1.101:11211']

});



// Set and get values (automatically distributed across nodes)

await client.set('mykey', 'Hello, Memcache!');

const value = await client.get('mykey');

console.log(value); // ['Hello, Memcache!']



// Close the connection

await client.quit();

```



You can also pass an array of MemcacheNode instances for advanced configuration:



```javascript

import { Memcache, createNode } from 'memcache';



// Create nodes with custom settings

const node1 = createNode('localhost', 11211, { weight: 2 });

const node2 = createNode('192.168.1.100', 11211, { weight: 1 });

const node3 = createNode('192.168.1.101', 11211, { weight: 1 });



// Create a client with MemcacheNode instances

const client = new Memcache({

  nodes: [node1, node2, node3],

  timeout: 10000

});



// node1 will receive twice as much traffic due to higher weight

await client.set('mykey', 'Hello, Memcache!');

const value = await client.get('mykey');

console.log(value); // ['Hello, Memcache!']



// Close the connection

await client.quit();

```



# API



## Constructor



```typescript

new Memcache(options?: string | MemcacheOptions)

```



Creates a new Memcache client instance. You can pass either:

- A **string** representing a single node URI (uses default settings)

- A **MemcacheOptions** object for custom configuration



**Examples:**



```javascript

// Single node as string

const client = new Memcache('localhost:11211');



// Single node with protocol

const client = new Memcache('memcache://192.168.1.100:11211');



// Multiple nodes with options

const client = new Memcache({

  nodes: ['localhost:11211', 'server2:11211'],

  timeout: 10000

});

```



### Options



- `nodes?: (string | MemcacheNode)[]` - Array of node URIs or MemcacheNode instances

  - Examples: `["localhost:11211", "memcache://192.168.1.100:11212"]`

- `timeout?: number` - Operation timeout in milliseconds (default: 5000)

- `keepAlive?: boolean` - Keep connection alive (default: true)

- `keepAliveDelay?: number` - Keep alive delay in milliseconds (default: 1000)

- `hash?: HashProvider` - Hash provider for consistent hashing (default: KetamaHash)

- `retries?: number` - Number of retry attempts for failed commands (default: 0)

- `retryDelay?: number` - Base delay in milliseconds between retries (default: 100)

- `retryBackoff?: RetryBackoffFunction` - Function to calculate backoff delay (default: fixed delay)

- `retryOnlyIdempotent?: boolean` - Only retry commands marked as idempotent (default: true)

- `autoDiscover?: AutoDiscoverOptions` - AWS ElastiCache Auto Discovery configuration (see [Auto Discovery](#auto-discovery))



## Properties



### `nodes: MemcacheNode[]` (readonly)

Returns the list of all MemcacheNode instances in the cluster.



### `nodeIds: string[]` (readonly)

Returns the list of node IDs (e.g., `["localhost:11211", "127.0.0.1:11212"]`).



### `hash: HashProvider`

Get or set the hash provider used for consistent hashing distribution.



### `timeout: number`

Get or set the timeout for operations in milliseconds (default: 5000).



### `keepAlive: boolean`

Get or set the keepAlive setting. Updates all existing nodes. Requires `reconnect()` to apply changes.



### `keepAliveDelay: number`

Get or set the keep alive delay in milliseconds. Updates all existing nodes. Requires `reconnect()` to apply changes.



### `retries: number`

Get or set the number of retry attempts for failed commands (default: 0).



### `retryDelay: number`

Get or set the base delay in milliseconds between retry attempts (default: 100).



### `retryBackoff: RetryBackoffFunction`

Get or set the backoff function for calculating retry delays.



### `retryOnlyIdempotent: boolean`

Get or set whether retries are restricted to idempotent commands only (default: true).



## Connection Management



### `connect(nodeId?: string): Promise`

Connect to all Memcache servers or a specific node.



### `disconnect(): Promise`

Disconnect all connections.



### `reconnect(): Promise`

Reconnect all nodes by disconnecting and connecting them again.



### `quit(): Promise`

Quit all connections gracefully.



### `isConnected(): boolean`

Check if any node is connected to a Memcache server.



## Node Management



### `getNodes(): MemcacheNode[]`

Get an array of all MemcacheNode instances.



### `getNode(id: string): MemcacheNode | undefined`

Get a specific node by its ID (e.g., `"localhost:11211"`).



### `addNode(uri: string | MemcacheNode, weight?: number): Promise`

Add a new node to the cluster. Throws error if node already exists.



### `removeNode(uri: string): Promise`

Remove a node from the cluster.



### `getNodesByKey(key: string): Promise`

Get the nodes for a given key using consistent hashing. Automatically connects to nodes if not already connected.



### `parseUri(uri: string): { host: string; port: number }`

Parse a URI string into host and port. Supports formats:

- Simple: `"localhost:11211"` or `"localhost"`

- Protocol: `"memcache://localhost:11211"`, `"tcp://localhost:11211"`

- IPv6: `"[::1]:11211"` or `"memcache://[2001:db8::1]:11212"`

- Unix socket: `"/var/run/memcached.sock"` or `"unix:///var/run/memcached.sock"`



## Data Storage Operations



### `get(key: string): Promise`

Get a value from the Memcache server. Returns the first successful result from replica nodes.



### `gets(keys: string[]): Promise>`

Get multiple values from the Memcache server. Returns a Map with keys to values.



### `set(key: string, value: string, exptime?: number, flags?: number): Promise`

Set a value in the Memcache server. Returns true only if all replica nodes succeed.

- `exptime` - Expiration time in seconds (default: 0 = never expire)

- `flags` - Flags/metadata (default: 0)



### `add(key: string, value: string, exptime?: number, flags?: number): Promise`

Add a value (only if key doesn't exist). Returns true only if all replica nodes succeed.



### `replace(key: string, value: string, exptime?: number, flags?: number): Promise`

Replace a value (only if key exists). Returns true only if all replica nodes succeed.



### `cas(key: string, value: string, casToken: string, exptime?: number, flags?: number): Promise`

Check-And-Set: Store a value only if it hasn't been modified since last fetch. Returns true only if all replica nodes succeed.



## String Modification Operations



### `append(key: string, value: string): Promise`

Append a value to an existing key. Returns true only if all replica nodes succeed.



### `prepend(key: string, value: string): Promise`

Prepend a value to an existing key. Returns true only if all replica nodes succeed.



## Deletion & Expiration



### `delete(key: string): Promise`

Delete a value from the Memcache server. Returns true only if all replica nodes succeed.



### `touch(key: string, exptime: number): Promise`

Update expiration time without retrieving value. Returns true only if all replica nodes succeed.



## Numeric Operations



### `incr(key: string, value?: number): Promise`

Increment a value. Returns the new value or undefined on failure.

- `value` - Amount to increment (default: 1)



### `decr(key: string, value?: number): Promise`

Decrement a value. Returns the new value or undefined on failure.

- `value` - Amount to decrement (default: 1)



## Server Management & Statistics



### `flush(delay?: number): Promise`

Flush all values from all Memcache servers. Returns true if all nodes successfully flushed.

- `delay` - Optional delay in seconds before flushing



### `stats(type?: string): Promise>`

Get statistics from all Memcache servers. Returns a Map of node IDs to their stats.



### `version(): Promise>`

Get the Memcache server version from all nodes. Returns a Map of node IDs to version strings.



## Validation



### `validateKey(key: string): void`

Validates a Memcache key according to protocol requirements. Throws error if:

- Key is empty

- Key exceeds 250 characters

- Key contains spaces, newlines, or null characters



## Helper Functions



### `createNode(host: string, port: number, options?: MemcacheNodeOptions): MemcacheNode`

Factory function to create a new MemcacheNode instance.



```javascript

import { createNode } from 'memcache';



const node = createNode('localhost', 11211, {

  timeout: 5000,

  keepAlive: true,

  weight: 1

});

```



# Hooks and Events



The Memcache client extends [Hookified](https://github.com/jaredwray/hookified) to provide powerful hooks and events for monitoring and customizing behavior.



## Events



The client emits various events during operations that you can listen to:



```javascript

const client = new Memcache();



// Connection events

client.on('connect', () => {

  console.log('Connected to Memcache server');

});



client.on('close', () => {

  console.log('Connection closed');

});



client.on('error', (error) => {

  console.error('Error:', error);

});



client.on('timeout', () => {

  console.log('Connection timeout');

});



// Cache hit/miss events

client.on('hit', (key, value) => {

  console.log(`Cache hit for key: ${key}`);

});



client.on('miss', (key) => {

  console.log(`Cache miss for key: ${key}`);

});

```



## Available Events



- `connect` - Emitted when connection to Memcache server is established

- `close` - Emitted when connection is closed

- `error` - Emitted when an error occurs

- `timeout` - Emitted when a connection timeout occurs

- `hit` - Emitted when a key is found in cache (includes key and value)

- `miss` - Emitted when a key is not found in cache

- `quit` - Emitted when quit command is sent

- `warn` - Emitted for warning messages

- `info` - Emitted for informational messages

- `autoDiscover` - Emitted on initial auto discovery with the cluster config

- `autoDiscoverUpdate` - Emitted when auto discovery detects a topology change

- `autoDiscoverError` - Emitted when auto discovery encounters an error



## Hooks



Hooks allow you to intercept and modify behavior before and after operations. Every operation supports `before` and `after` hooks.



```javascript

const client = new Memcache();



// Add a before hook for get operations

client.onHook('before:get', async ({ key }) => {

  console.log(`Getting key: ${key}`);

});



// Add an after hook for set operations

client.onHook('after:set', async ({ key, value, success }) => {

  if (success) {

    console.log(`Successfully set ${key}`);

  }

});



// Hooks can be async and modify behavior

client.onHook('before:set', async ({ key, value }) => {

  console.log(`About to set ${key} = ${value}`);

  // Perform validation, logging, etc.

});

```



## Available Hooks



All operations support before and after hooks with specific parameters:



## get(key)

- `before:get` - `{ key }`

- `after:get` - `{ key, value }` (value is array or undefined)



## set(key, value, exptime?, flags?)

- `before:set` - `{ key, value, exptime, flags }`

- `after:set` - `{ key, value, exptime, flags, success }`



## gets(keys[])

- `before:gets` - `{ keys }`

- `after:gets` - `{ keys, values }` (values is a Map)



## add(key, value, exptime?, flags?)

- `before:add` - `{ key, value, exptime, flags }`

- `after:add` - `{ key, value, exptime, flags, success }`



## replace(key, value, exptime?, flags?)

- `before:replace` - `{ key, value, exptime, flags }`

- `after:replace` - `{ key, value, exptime, flags, success }`



## append(key, value)

- `before:append` - `{ key, value }`

- `after:append` - `{ key, value, success }`



## prepend(key, value)

- `before:prepend` - `{ key, value }`

- `after:prepend` - `{ key, value, success }`



## delete(key)

- `before:delete` - `{ key }`

- `after:delete` - `{ key, success }`



## incr(key, value?)

- `before:incr` - `{ key, value }`

- `after:incr` - `{ key, value, newValue }`



## decr(key, value?)

- `before:decr` - `{ key, value }`

- `after:decr` - `{ key, value, newValue }`



## touch(key, exptime)

- `before:touch` - `{ key, exptime }`

- `after:touch` - `{ key, exptime, success }`



## Hook Examples



```javascript

const client = new Memcache();



// Log all get operations

client.onHook('before:get', async ({ key }) => {

  console.log(`[GET] Fetching key: ${key}`);

});



client.onHook('after:get', async ({ key, value }) => {

  console.log(`[GET] Key: ${key}, Found: ${value !== undefined}`);

});



// Log all set operations with timing

client.onHook('before:set', async (context) => {

  context.startTime = Date.now();

});



client.onHook('after:set', async (context) => {

  const duration = Date.now() - context.startTime;

  console.log(`[SET] Key: ${context.key}, Success: ${context.success}, Time: ${duration}ms`);

});

```



# Distribution Algorithms



Memcache supports pluggable distribution algorithms to determine how keys are distributed across nodes. You can configure the algorithm using the `hash` option.



## KetamaHash (Default)



KetamaHash uses the Ketama consistent hashing algorithm, which minimizes key redistribution when nodes are added or removed. This is the default and recommended algorithm for production environments with dynamic scaling.



```javascript

import { Memcache } from 'memcache';



// KetamaHash is used by default

const client = new Memcache({

  nodes: ['server1:11211', 'server2:11211', 'server3:11211']

});

```



**Characteristics:**

- Minimal key redistribution (~1/n keys move when adding/removing nodes)

- Uses virtual nodes for better distribution

- Supports weighted nodes

- Best for production environments with dynamic scaling



## ModulaHash



ModulaHash uses a simple modulo-based hashing algorithm (`hash(key) % nodeCount`). This is a simpler algorithm that may redistribute all keys when nodes change.



```javascript

import { Memcache, ModulaHash } from 'memcache';



// Use ModulaHash for distribution

const client = new Memcache({

  nodes: ['server1:11211', 'server2:11211', 'server3:11211'],

  hash: new ModulaHash()

});



// With a custom hash algorithm (default is sha1)

const client2 = new Memcache({

  nodes: ['server1:11211', 'server2:11211'],

  hash: new ModulaHash('md5')

});

```



**Characteristics:**

- Simple and fast algorithm

- All keys may be redistributed when nodes are added or removed

- Supports weighted nodes (nodes with higher weight appear more in the distribution)

- Best for fixed-size clusters or testing environments



### Weighted Nodes with ModulaHash



ModulaHash supports weighted nodes, where nodes with higher weights receive proportionally more keys:



```javascript

import { Memcache, ModulaHash, createNode } from 'memcache';



// Create nodes with different weights

const node1 = createNode('server1', 11211, { weight: 3 }); // 3x traffic

const node2 = createNode('server2', 11211, { weight: 1 }); // 1x traffic



const client = new Memcache({

  nodes: [node1, node2],

  hash: new ModulaHash()

});



// server1 will receive approximately 75% of keys

// server2 will receive approximately 25% of keys

```



## Choosing an Algorithm



| Feature | KetamaHash | ModulaHash |

|---------|------------|------------|

| Key redistribution on node change | Minimal (~1/n keys) | All keys may move |

| Complexity | Higher (virtual nodes) | Lower (simple modulo) |

| Performance | Slightly slower | Faster |

| Best for | Dynamic scaling | Fixed clusters |

| Weighted nodes | Yes | Yes |



**Use KetamaHash (default) when:**

- Your cluster size may change dynamically

- You want to minimize cache invalidation during scaling

- You're running in production



**Use ModulaHash when:**

- Your cluster size is fixed

- You prefer simplicity over minimal redistribution

- You're in a testing or development environment



# Retry Configuration



The Memcache client supports automatic retry of failed commands with configurable backoff strategies.



## Basic Retry Setup



Enable retries by setting the `retries` option:



```javascript

import { Memcache } from 'memcache';



const client = new Memcache({

  nodes: ['localhost:11211'],

  retries: 3,        // Retry up to 3 times

  retryDelay: 100    // 100ms between retries

});

```



You can also modify retry settings at runtime:



```javascript

client.retries = 5;

client.retryDelay = 200;

```



## Backoff Strategies



The client includes two built-in backoff functions:



### Fixed Delay (Default)



```javascript

import { Memcache, defaultRetryBackoff } from 'memcache';



const client = new Memcache({

  retries: 3,

  retryDelay: 100,

  retryBackoff: defaultRetryBackoff  // 100ms, 100ms, 100ms

});

```



### Exponential Backoff



```javascript

import { Memcache, exponentialRetryBackoff } from 'memcache';



const client = new Memcache({

  retries: 3,

  retryDelay: 100,

  retryBackoff: exponentialRetryBackoff  // 100ms, 200ms, 400ms

});

```



### Custom Backoff Function



You can provide your own backoff function:



```javascript

const client = new Memcache({

  retries: 3,

  retryDelay: 100,

  retryBackoff: (attempt, baseDelay) => {

    // Exponential backoff with jitter

    const delay = baseDelay * Math.pow(2, attempt);

    return delay + Math.random() * delay * 0.1;

  }

});

```



The backoff function receives:

- `attempt` - The current attempt number (0-indexed)

- `baseDelay` - The configured `retryDelay` value



## Idempotent Safety



**Important:** By default, retries are only performed for commands explicitly marked as idempotent. This prevents accidental double-execution of non-idempotent operations like `incr`, `decr`, `append`, and `prepend`.



### Why This Matters



If a network timeout occurs after the server applies a mutation but before the client receives the response, retrying would apply the mutation twice:

- Counter incremented twice instead of once

- Data appended twice instead of once



### Safe Usage Patterns



**For read operations (always safe to retry):**



```javascript

// Mark read operations as idempotent

await client.execute('get mykey', nodes, { idempotent: true });

```



**For idempotent writes (safe to retry):**



```javascript

// SET with the same value is idempotent

await client.execute('set mykey 0 0 5\r\nhello', nodes, { idempotent: true });

```



**Disable safety for all commands (use with caution):**



```javascript

const client = new Memcache({

  retries: 3,

  retryOnlyIdempotent: false  // Allow retries for ALL commands

});

```



### Behavior Summary



| `retryOnlyIdempotent` | `idempotent` flag | Retries enabled? |

|-----------------------|-------------------|------------------|

| `true` (default)      | `false` (default) | No               |

| `true` (default)      | `true`            | Yes              |

| `false`               | (any)             | Yes              |



### Methods Without Retry Support



The following methods do not use the retry mechanism and have their own error handling:



- `get()` - Returns `undefined` on failure

- `gets()` - Returns partial results on node failure

- `flush()` - Operates directly on nodes

- `stats()` - Operates directly on nodes

- `version()` - Operates directly on nodes



To use retries with read operations, use the `execute()` method directly:



```javascript

const nodes = await client.getNodesByKey('mykey');

const results = await client.execute('get mykey', nodes, { idempotent: true });

```



# SASL Authentication



The Memcache client supports SASL (Simple Authentication and Security Layer) authentication using the PLAIN mechanism. This allows you to connect to memcached servers that require authentication.



## Enabling SASL Authentication



```javascript

import { Memcache } from 'memcache';



const client = new Memcache({

  nodes: ['localhost:11211'],

  sasl: {

    username: 'myuser',

    password: 'mypassword',

  },

});



await client.connect();

// Client is now authenticated and ready to use

```



## SASL Options



The `sasl` option accepts an object with the following properties:



- `username: string` - The username for authentication (required)

- `password: string` - The password for authentication (required)

- `mechanism?: 'PLAIN'` - The SASL mechanism to use (default: 'PLAIN')



Currently, only the PLAIN mechanism is supported.



## Binary Protocol Methods



**Important:** Memcached servers with SASL enabled (`-S` flag) require the binary protocol for all operations after authentication. The standard text-based methods (`client.get()`, `client.set()`, etc.) will not work on SASL-enabled servers.



Use the `binary*` methods on nodes for SASL-enabled servers:



```javascript

import { Memcache } from 'memcache';



const client = new Memcache({

  nodes: ['localhost:11211'],

  sasl: { username: 'user', password: 'pass' },

});



await client.connect();



// Access the node directly for binary operations

const node = client.nodes[0];



// Binary protocol operations

await node.binarySet('mykey', 'myvalue', 3600);     // Set with 1 hour expiry

const value = await node.binaryGet('mykey');         // Get value

await node.binaryDelete('mykey');                    // Delete key



// Other binary operations

await node.binaryAdd('newkey', 'value');             // Add (only if not exists)

await node.binaryReplace('existingkey', 'newvalue'); // Replace (only if exists)

await node.binaryIncr('counter', 1);                 // Increment

await node.binaryDecr('counter', 1);                 // Decrement

await node.binaryAppend('mykey', '-suffix');         // Append to value

await node.binaryPrepend('mykey', 'prefix-');        // Prepend to value

await node.binaryTouch('mykey', 7200);               // Update expiration

await node.binaryFlush();                            // Flush all

const version = await node.binaryVersion();          // Get server version

const stats = await node.binaryStats();              // Get server stats

```



## Per-Node SASL Configuration



You can also configure SASL credentials when creating individual nodes:



```javascript

import { createNode } from 'memcache';



// Create a node with SASL credentials

const node = createNode('localhost', 11211, {

  sasl: { username: 'user', password: 'pass' },

});



// Connect and use binary methods

await node.connect();

await node.binarySet('mykey', 'hello');

const value = await node.binaryGet('mykey');

```



## Authentication Events



You can listen for authentication events on both nodes and the client:



```javascript

import { Memcache, MemcacheNode } from 'memcache';



// Node-level events

const node = new MemcacheNode('localhost', 11211, {

  sasl: { username: 'user', password: 'pass' },

});



node.on('authenticated', () => {

  console.log('Node authenticated successfully');

});



node.on('error', (error) => {

  if (error.message.includes('SASL authentication failed')) {

    console.error('Authentication failed:', error.message);

  }

});



await node.connect();



// Client-level events (forwarded from nodes)

const client = new Memcache({

  nodes: ['localhost:11211'],

  sasl: { username: 'user', password: 'pass' },

});



client.on('authenticated', () => {

  console.log('Client authenticated');

});



await client.connect();

```



### Node Properties



- `node.hasSaslCredentials` - Returns `true` if SASL credentials are configured

- `node.isAuthenticated` - Returns `true` if the node has successfully authenticated



## Server Configuration



To use SASL authentication, your memcached server must be configured with SASL support:



1. **Build memcached with SASL support** - Ensure memcached was compiled with `--enable-sasl`



2. **Create SASL users** - Use `saslpasswd2` to create users:

   ```bash

   saslpasswd2 -a memcached -c username

   ```



3. **Configure SASL mechanism** - Create `/etc/sasl2/memcached.conf`:

   ```

   mech_list: plain

   ```



4. **Start memcached with SASL** - Use the `-S` flag:

   ```bash

   memcached -S -m 64 -p 11211

   ```



For more details, see the [memcached SASL documentation](https://github.com/memcached/memcached/wiki/SASLHowto).



# Auto Discovery



The Memcache client supports AWS ElastiCache Auto Discovery, which automatically detects cluster topology changes and adds or removes nodes as needed. When enabled, the client connects to a configuration endpoint, retrieves the current list of cache nodes, and periodically polls for changes.



## Enabling Auto Discovery



```javascript

import { Memcache } from 'memcache';



const client = new Memcache({

  nodes: [],

  autoDiscover: {

    enabled: true,

    configEndpoint: 'my-cluster.cfg.use1.cache.amazonaws.com:11211',

  },

});



await client.connect();

// The client automatically discovers and connects to all cluster nodes

```



If you omit `configEndpoint`, the first node in the `nodes` array is used as the configuration endpoint:



```javascript

const client = new Memcache({

  nodes: ['my-cluster.cfg.use1.cache.amazonaws.com:11211'],

  autoDiscover: {

    enabled: true,

  },

});

```



## Auto Discovery Options



The `autoDiscover` option accepts an object with the following properties:



- `enabled: boolean` - Enable auto discovery of cluster nodes (required)

- `pollingInterval?: number` - How often to poll for topology changes, in milliseconds (default: 60000)

- `configEndpoint?: string` - The configuration endpoint to use for discovery. This is typically the `.cfg` endpoint from ElastiCache. If not specified, the first node in the `nodes` array will be used

- `useLegacyCommand?: boolean` - Use the legacy `get AmazonElastiCache:cluster` command instead of `config get cluster` (default: false)



## Auto Discovery Events



The client emits events during the auto discovery lifecycle:



```javascript

const client = new Memcache({

  nodes: [],

  autoDiscover: {

    enabled: true,

    configEndpoint: 'my-cluster.cfg.use1.cache.amazonaws.com:11211',

  },

});



// Emitted on initial discovery with the full cluster config

client.on('autoDiscover', (config) => {

  console.log('Discovered nodes:', config.nodes);

  console.log('Config version:', config.version);

});



// Emitted when polling detects a topology change

client.on('autoDiscoverUpdate', (config) => {

  console.log('Cluster topology changed:', config.nodes);

});



// Emitted when discovery encounters an error (non-fatal, retries on next poll)

client.on('autoDiscoverError', (error) => {

  console.error('Discovery error:', error.message);

});



await client.connect();

```



## Legacy Command Support



For ElastiCache engine versions older than 1.4.14, use the legacy discovery command:



```javascript

const client = new Memcache({

  nodes: [],

  autoDiscover: {

    enabled: true,

    configEndpoint: 'my-cluster.cfg.use1.cache.amazonaws.com:11211',

    useLegacyCommand: true, // Uses 'get AmazonElastiCache:cluster' instead of 'config get cluster'

  },

});

```



# IPv6 Support



The Memcache client fully supports IPv6 addresses using standard bracket notation in URIs.



## Connecting to IPv6 Nodes



```javascript

import { Memcache } from 'memcache';



// IPv6 loopback

const client = new Memcache('[::1]:11211');



// Multiple IPv6 nodes

const client = new Memcache({

  nodes: [

    '[::1]:11211',

    '[2001:db8::1]:11211',

    'memcache://[2001:db8::2]:11212',

  ],

});



await client.connect();

```



## IPv6 in Auto Discovery



When auto discovery returns IPv6 node addresses, the client automatically brackets them for correct URI handling:



```javascript

const client = new Memcache({

  nodes: [],

  autoDiscover: {

    enabled: true,

    configEndpoint: '[2001:db8::1]:11211',

  },

});



await client.connect();

// Discovered IPv6 nodes are added as [host]:port automatically

```



## IPv6 Node IDs



Node IDs for IPv6 addresses use bracket notation to avoid ambiguity:



```javascript

const client = new Memcache({

  nodes: ['[::1]:11211', '[2001:db8::1]:11212'],

});



console.log(client.nodeIds);

// ['[::1]:11211', '[2001:db8::1]:11212']

```



# Benchmarks



These are provided to show a simple benchmark against current libraries. This is not robust but it is something we update regularly to make sure we are keeping performant.



|             name             |  summary  |  ops/sec  |  time/op  |  margin  |  samples  |

|------------------------------|:---------:|----------:|----------:|:--------:|----------:|

|  memcache set/get (v1.4.0)   |    🥇     |       3K  |    350µs  |  ±0.19%  |      10K  |

|  memcached set/get (v2.2.2)  |   -2.9%   |       3K  |    361µs  |  ±0.16%  |      10K  |

|  memjs set/get (v1.3.2)      |   -12%    |       3K  |    398µs  |  ±0.17%  |      10K  |



# Contributing



Please read our [Contributing Guidelines](./CONTRIBUTING.md) and also our [Code of Conduct](./CODE_OF_CONDUCT.md).



# License and Copyright



[MIT & Copyright (c) Jared Wray](https://github.com/jaredwray/memcache/blob/main/LICENSE)