PG Lock

Description

參考 colonist4/pg-mutex-lock 完善 postgres 諮詢鎖功能，並使用 pg pool 解決斷線自動重連 Refer to colonist4/pg-mutex-lock to improve postgres advisory lock function, and use pg pool to solve disconnection and automatic reconnection

Feature

• Support multi-process mutex lock
• Support single-process mutex lock
• Support retry, timeout configuration
• Full typescript support
• Support pg pool

API

class PGLock

This class is entry point of features. All functions are located under this class instance.

Options

| Name | Type | Required | Default | Description | |------|------|----------|---------|----| | pool | Pool | no | undefined | use other pg pool (Create if empty) | | poolConfig | PoolConfig | yes | undefined | refer to PoolConfig | | timeout | number | no | 10 * 1000 | acquire lock timeout | | retryCount | number | no | 3 | acquire lock retry count |

Method acquireLock (client: PoolClient, key: string) : Promise<boolean>

Try to acquire lock for given key. If success, will be resolved with true. If failed, will be rejected.

Method releaseLock (client: PoolClient, key: string) : Promise<boolean>

Try to release lock for given key. It directly return results of pg_advisory_unlock.

Method lock (key: string, func: () => Promise<any>) : Promise<any>

Mutex lock by async function.

Example

import { PGLock } from 'pglock-v2'

const pgLock = new PGLock({
  poolConfig: {
    host: 'localhost',
    port: 5432,
    user: 'postgres',
    password: 'password',
    database: 'database',
  },
})

setTimeout(async () => {
  console.log('start A')
  await pgLock.lock('test', async () => {
    console.log('locked A')
    await wait(1000)
    console.log('unlocked A')
  })
}, 100)

setTimeout(async () => {
  console.log('start B')
  await pgLock.lock('test', async () => {
    console.log('locked B')
    await wait(100)
    console.log('unlocked B')
  })
}, 300)

Dependencies

• pg (https://github.com/brianc/node-postgres)