node-redlock/docs/example.ts.md

A distributed locking algorithm used to manage distributed resources in a system.

 Introduction and Overview
---------------------------

This TypeScript/JavaScript code is a simple example of how to use the `ioredis` and `redlock` libraries for managing distributed locks in a Node.js application. The code demonstrates how to create clients for Redis, a popular key-value store, using both the `ioredis` library and the `redis-sentinel` package. It then shows how to use these clients with the `redlock` library to acquire and release locks on a resource.

System Architecture
---------------------------

The architecture of this system is based on the client-server model, where the Redis server acts as the central data store and the Node.js application acts as the client that interacts with the Redis server. The `redlock` library is used to manage distributed locks across multiple Redis clients, ensuring that only one client can acquire a lock at a time.

Data Design
---------------------------

The code uses Redis as the data store, which stores key-value pairs. In this example, the key is a string representing a resource, and the value is a boolean indicating whether the lock is currently held.

Interface Design
---------------------------

There are no user interfaces in this code, as it is focused on the internal workings of the application rather than its interaction with users.

Component Design
---------------------------

The main components in this code are:

* `Redis`: a class that represents a Redis client created using the `ioredis` library.
* `IoredisClient`: an interface that defines the methods for interacting with a Redis client.
* `RedisJsClient`: a class that implements the `IoredisClient` interface and provides additional functionality for managing distributed locks using `redlock`.
* `Redlock`: a class that manages distributed locks across multiple Redis clients.

User Interface Design
---------------------------

There is no user interface in this code, as it is focused on the internal workings of the application rather than its interaction with users.

Assumptions and Dependencies
-------------------------------

* The `ioredis` and `redis-sentinel` libraries are installed and properly configured.
* The Redis server is running and accessible from the Node.js application.
* The `redlock` library is installed and properly configured.

Glossary of Terms
---------------------------

* Redis: a popular key-value store that is used as the data store in this example.
* Distributed lock: a mechanism for ensuring that only one client can access a resource at a time, even when multiple clients are running concurrently.
* Redis client: an object that represents a connection to a Redis server and provides methods for interacting with the server.
* `IoredisClient`: an interface that defines the methods for interacting with a Redis client.
* `RedisJsClient`: a class that implements the `IoredisClient` interface and provides additional functionality for managing distributed locks using `redlock`.
* `Redlock`: a class that manages distributed locks across multiple Redis clients.

Class Diagram (in Mermaid syntax)
---------------------------------
```mermaid
class Redis {
  host: string;
  port: number;
  
  constructor(options: object) {
    this.host = options.host;
    this.port = options.port;
  }
}

interface IRedisClient {
  get(key: string): Promise<string | null>;
  set(key: string, value: boolean): Promise<void>;
  quit(): Promise<void>;
}

class RedisJsClient implements IRedisClient {
  url: string;
  
  constructor(options: object) {
    this.url = options.url;
  }
  
  async get(key: string): Promise<string | null> {
    // Implementation of the get method
  }
  
  async set(key: string, value: boolean): Promise<void> {
    // Implementation of the set method
  }
  
  async quit(): Promise<void> {
    // Implementation of the quit method
  }
}

class Redlock {
  clients: IRedisClient[];
  
  constructor(clients: IRedisClient[]) {
    this.clients = clients;
  }
  
  async acquireLock(resource: string, ttl: number): Promise<boolean | null> {
    // Implementation of the acquireLock method
  }
  
  async releaseLock(resource: string, lockValue: boolean | null): Promise<void> {
    // Implementation of the releaseLock method
  }
}
```