LightQ ✨

A simple, lightweight, Redis-backed job queue library designed for TypeScript applications. LightQ provides essential queueing features with a focus on reliability and ease of use, leveraging atomic Redis operations via Lua scripts.

Features

• ✅ Simple API: Easy-to-understand interface for adding and processing jobs.
• 🚀 Redis Backend: Uses Redis for persistence, ensuring jobs are not lost.
• 🔒 Atomic Operations: Leverages Lua scripts for safe, atomic state transitions in Redis.
• 🔷 TypeScript Native: Written entirely in TypeScript with types included.
• 🕒 Delayed Jobs: Schedule jobs to run after a specific delay.
• 🗓️ Scheduled Jobs: Define recurring jobs using cron patterns or fixed intervals via the integrated Job Scheduler.
• 🔄 Automatic Retries: Failed jobs can be automatically retried with configurable backoff strategies (fixed, exponential).
• ⚖️ Concurrency Control: Limit the number of jobs a worker processes concurrently.
• 🧹 Job Lifecycle Events: Emit events for active, completed, failed, retrying, etc. (including scheduler-specific events).
• 🗑️ Automatic Cleanup: Optionally remove job data automatically upon completion or failure.

Installation

# Using npm
npm install @jlucaso/lightq

# Using yarn
yarn add @jlucaso/lightq

# Using Bun
bun add @jlucaso/lightq

Prerequisite: Requires a running Redis server (version 4.0 or later recommended due to Lua script usage). ioredis is used as the Redis client.

Basic Usage

Check the example/index.ts file for a comprehensive demonstration, including:

• Creating Queues and Workers.
• Adding immediate, delayed, and failing jobs.
• Setting up and removing scheduled jobs.
• Handling various job lifecycle events.

API Overview

Queue<TData, TResult, TName>

• constructor(name: string, opts: QueueOptions): Creates a new queue instance.
• add(name: TName, data: TData, opts?: JobOptions): Promise<Job<TData, TResult, TName>>: Adds a single job to the queue.
• addBulk(jobs: { name: TName; data: TData; opts?: JobOptions }[]): Promise<Job<TData, TResult, TName>[]>: Adds multiple jobs efficiently.
• upsertJobScheduler(schedulerId: string, repeat: SchedulerRepeatOptions, template: JobTemplate): Promise<void>: Creates or updates a recurring job schedule associated with this queue. Starts the scheduler polling process if needed.
• removeJobScheduler(schedulerId: string): Promise<boolean>: Removes a specific job schedule associated with this queue.
• getJob(jobId: string): Promise<Job<TData, TResult, TName> | null>: Retrieves job details by ID.
• getJobCounts(): Promise<{ wait: number; active: number; ... }>: Gets the number of jobs in different states.
• close(): Promise<void>: Closes the Redis connection used by the queue (and its associated scheduler, if active).
• Events: error, ready, waiting, closing, closed, scheduler_error, scheduler_job_added.

Worker<TData, TResult, TName>

• constructor(name: string, processor: Processor<TData, TResult, TName>, opts: WorkerOptions): Creates a worker instance to process jobs from the specified queue.
  • The processor function takes a Job object and should return a Promise resolving with the job's result or throwing an error if it fails.
• close(force?: boolean): Promise<void>: Closes the worker. By default, it waits for active jobs to complete. force = true attempts a faster shutdown.
• Events:
  • active: Job started processing. (job: Job) => void
  • completed: Job finished successfully. (job: Job, result: TResult) => void
  • failed: Job failed (possibly after retries). (job: Job | undefined, error: Error) => void
  • error: An error occurred within the worker itself (e.g., Redis connection issue, lock renewal failure). (error: Error, job?: Job) => void
  • retrying: Job failed but will be retried. (job: Job, error: Error) => void
  • movedDelayed: Delayed jobs were moved to the wait list. (count: number) => void
  • ready: Worker connected to Redis. () => void
  • closing: Worker is starting the closing process. () => void
  • closed: Worker has finished closing. () => void

Job<TData, TResult, TName>

• Represents a single job instance. Contains properties like:
  • id: Unique job ID.
  • name: Job name provided during add.
  • data: The payload provided during add.
  • opts: Job-specific options.
  • attemptsMade: How many times this job has been attempted.
  • progress: (Note: updateProgress is currently not fully implemented).
  • returnValue: The result returned by the processor upon completion.
  • failedReason: The error message if the job failed permanently.
  • stacktrace: Stack trace if the job failed.

JobScheduler

• While not typically instantiated directly, the JobScheduler class manages recurring job schedules. It's accessed via the Queue's upsertJobScheduler and removeJobScheduler methods. It runs a background process to check for due schedules and adds corresponding jobs to the queue.
• Events (Forwarded via Queue): error, job_added, upsert, remove, start, stop, closing, closed.

Configuration

QueueOptions

• connection: IORedis connection options or an existing IORedis instance.
• prefix: Redis key prefix (default: lightq).
• defaultJobOptions: Default JobOptions applied to all jobs added to this queue.
• (Implicitly used by Scheduler): prefix is used as the base for scheduler keys unless schedulerPrefix is provided in JobSchedulerOptions.

WorkerOptions

• Extends QueueOptions.
• concurrency: Max number of jobs to process concurrently (default: 1).
• lockDuration: Time (ms) a job is locked during processing (default: 30000).
• lockRenewTime: Interval (ms) before lock expiration to attempt renewal (default: lockDuration / 2).
• removeOnComplete: true to delete job data on success, or a number to keep only the latest N completed jobs' data (Note: Trimming by count requires uncommenting Lua script logic). Default: false.
• removeOnFail: true to delete job data on final failure, or a number to keep only the latest N failed jobs' data (Note: Trimming by count requires uncommenting Lua script logic). Default: false.

JobOptions

• jobId: Assign a custom job ID (cannot start with scheduler:).
• delay: Delay (ms) before the job should be processed.
• attempts: Max number of times to attempt the job (default: 1).
• backoff: Backoff strategy for retries: number (fixed delay ms) or { type: 'fixed' | 'exponential', delay: number }.
• removeOnComplete: Overrides worker/queue default.
• removeOnFail: Overrides worker/queue default.

Scheduler Configuration

• JobSchedulerOptions (extends QueueOptions): Options for the scheduler instance (usually configured internally by the Queue).
  • checkInterval: How often (ms) the scheduler checks for due jobs (default: 5000).
  • schedulerPrefix: Specific Redis key prefix for scheduler data (defaults to prefix from QueueOptions).
• SchedulerRepeatOptions: Defines when scheduled jobs run.
  • { pattern: string, tz?: string }: A cron pattern string and optional timezone (e.g., pattern: '0 * * * *' for hourly).
  • { every: number }: A repeat interval in milliseconds (e.g., every: 60000 for every minute).
• JobTemplate: Defines the job created by the scheduler.
  • name: The name of the job to be added to the queue.
  • data?: The data payload for the job.
  • opts?: JobOptions for the created job (cannot include jobId or delay).

Contributing

Contributions are welcome! Please feel free to open an issue or submit a pull request.

License

Licensed under the MIT License.