AC KeyLock

This tool can be used to lock operations (e.g. make sure workers will fetch a job only once). You can use it with Redis as distributed lock systems or with the built-in memory cache.

This package is a successor of ac-redisLock and can easily replace ac-redisLock. Please note, that callback-style is no longer available.

Usage

Init

Init function requires a valid redis instance.

• redis - OPTIONAL INSTANCE ioredis instance
• logger - OPTIONAL INSTANCE logger instance (e.g. Winston)
• logLevel - OPTIONAL STRING logLevel for the Redis operation

await keylock.init()
// OR WITH REDIS
await keylock.init({ redis: REDISINSTANCE })

Lock key

LockKey has the following parameters

• key - STRING required name for the key
• expires - OPTIONAL INT seconds after the lock is released, defaults to 10 seconds
• value - OPTIONAL STRING value for this redisKey. Use it to compare/secure lock values

await keylock.lockKey(params)
// return values
{ status: 423 } -> there is already a lock on this key
{ value: 'xxxx' } -> a lock has been put on this key

Release lock

ReleaseKey has the following parameters

• key - STRING required name for the key
• value - OPTIONAL STRING if set will be compared with the redisKey value before releasing. If not matching, the function will return an error message

await keylock.releaseLock(params, [callback])
// return values
{ status: 200 } -> lock has been released and deleted

Examples

Usage with Redis

const keyLock = require('ac-keylock')

// create a Redis instance (using io-redis)
const app.redisInstance = new Redis(options)

await keyLock.init({
  redis: app.redisInstance 
})

const params = {
  key: 'someMeaningfulKey',
}
let result = await keyLock.lockKey(params)
// { status: 423 } -> key is locked
// { value } -> value for this lock -> set as params.value for releaseLock

// redisKey is deleted and lock released
await keyLock.releaseKey(params)
// { status: 200 }

Usage with built-in memory cache

const keyLock = require('ac-keylock')

await keyLock.init()

const params = {
  key: 'someMeaningfulKey',
}
let result = await keyLock.lockKey(params)
// { status: 423 } -> key is locked
// { value } -> value for this lock -> set as params.value for releaseLock

// redisKey is deleted and lock released
await keyLock.releaseKey(params)
// { status: 200 }

Links

• Website
• Twitter (@admiralcloud)
• Facebook

License

MIT License Copyright © 2009-present, AdmiralCloud AG, Mark Poepping