zkt-updater

fast and reliable inventory cache based on redis

Install

npm install zkt-updater

Usage

const updater = new ZKTUpdater('ticketInventory', {
    async get(id, ctx) {
        let t = await db.query("select total from ticket_product where ticket_product_id=? limit 1", [id]);
        return t.total * 1;
    },
    async change(id, diff, ctx) {
        //diff < 0
        await db.query("update ticket_product set total = total + ? where ticket_product_id = ?", [diff, id]);
    }
});
 
//...
 
 
router.post('/create_order', async ctx => {
 
    let { ticket_product_id, tickets } = ctx.query;
 
    let left_total = await updater.incrby(ticket_product_id, -tickets, ctx);
    if (left_total >= 0) {
        await create_order(ctx);
    }
    //...
});
 
 

Options

get(id, ...args) get value function, returns Promise

change(id, diff, ...args) update value function, returns Promise

changeDelay (default 1 second), when value changed in redis, wait some time before call the change function

redisOptions default: process.env.REDIS_URL